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I think I have a major brake bias problem on my 99 SVT. After a hard stop, I can touch the rear rotors and they feel maybe like 110 deg F. The fronts are nearly smoking hot (pretty technical eh?) and sizzle when snow is tossed on them. I wouldn't dare touch them.
Sorry but I don't have an IR temp guage.
I just replaced both rear calipers, probably unecessarily. They are bleed and have new pads and rotors.
Is the front/rear bias built into the master cylinder? Is there a separate proportioning valve? Has anyone else had this issue?
Thanks! (yes I searched and searched)
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The front brakes do about 80% of the braking so they do run hotter than the rears.
How does the car stop? If it stops OK, you probably have nothing to worry about.
Jim Johnson
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yeah, the front breaks get extremely hot, the rear ones dont... the front does about 80% of the slowing, the rear pick up the extra slack and make it a nice controlled brake. Rather then stopping hard and having your rear end freak out... I remember when I was only running on front brakes because one of my brake cylenders had blown... Such crappy braking.
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Thanks - I certainly realize that the fronts handle a majority of the braking (>70%) but that fact doesn't mean a case can't arise where the backs are still far under-biased from where they should be.
Which is exactly the situation I have.
I'll have to collect some IR temps from other 4 wheel brake vehicles. But on a new Freestar the temps in the rear were very similar to the front. Both "sizzled" with the caveman snow test on the rotor after heavy braking.
I would also think the anti-lock braking system would allow more rear braking than typical, since it can prevent a lockup and the resulted instability that non-ABS vehicles fear.
Any other ideas? Has anyone installed an aftermarket proportioning valve?
Also - my pad wear in the rear is tiny compared to the front.
Bottom line - my rear brakes are useless and I can't figure out why.
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2 things. Don't f#$K with the bias and don't be throwing snow on your rotors after hard stops! 
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Originally posted by Stazi:
2 things.
Don't f#$K with the bias and don't be throwing snow on your rotors after hard stops!
Maybe he likes warped rotors? 
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Originally posted by CSVT1214:
Originally posted by Stazi:
2 things.
Don't f#$K with the bias and don't be throwing snow on your rotors after hard stops!
Maybe he likes warped rotors?
Guys - give me a break - or brake. It is only a TINY bit of snow, like 3 thimbles full.
I'll get an IR temp gauge and collect some data. It is not biased anything near to correct.
And I will replace the master cylinder, or bleed better, or f#$k with my bias to get it working better. Something is not right.
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Originally posted by 99fordsvt:
Any other ideas? Has anyone installed an aftermarket proportioning valve?
Also - my pad wear in the rear is tiny compared to the front.
Bottom line - my rear brakes are useless and I can't figure out why.
An 'aftermarket proportioning valve' isn't going to do anything for you. Unless you plan on removing all the factory vlaving and pulling the ABS it's worthless. They don't increase pressure. They simply reduce what is already there.
Rear pad wear will be about 4:1 in time. Pretty common.
Want them to work better? Put 200lbs in the trunk. They'll get hot then.
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Originally posted by Todd TCE:
Want them to work better? Put 200lbs in the trunk. They'll get hot then.
How is that? Are you saying the ABS is preventing the rears from gripping? I understand it's the lack of weight in the rear that is reason for front-biased brakes, but I fail so see how adding weight would result in any change in braking. The system isn't dyanamic in any way I know of, except ABS.
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Your ABS wil not even be involved unless you are braking hard enough to invoke it. When you do you will hear a rumble as well as fell a very rapid brake pulsation.
On some of the Contours, the rear brake pressure bias is controlled by pressure reducing valves in line where the steel brake line connects to the rear brakes hoses for each individual caliper. I wouldn't mess with them unless you like having the car swap ends on hard braking. When these valves act up, they cause that one caliper to not fully release. The valves are different between ABS and non-ABS and are not interchangable.
If you can find a shop that is willing to loan the gauges (if they have them, and they are expensive) you could read the rear brake caliper line pressure and find a like car to compare it with.
Jim Johnson
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Originally posted by Todd TCE:
Originally posted by 99fordsvt:
An 'aftermarket proportioning valve' isn't going to do anything for you. Unless you plan on removing all the factory vlaving and pulling the ABS it's worthless. They don't increase pressure. They simply reduce what is already there.
Rear pad wear will be about 4:1 in time. Pretty common.
Want them to work better? Put 200lbs in the trunk. They'll get hot then.
OK - then proportion the front line pressure down, leaving the rears untouched. My pad wear is more like 100:1, that is why I'm fishing for advice.
Nice conversation, but this is not about fine tuning the bias - it is about a majorly upset 99% front condition.
I don't agree that adding weight to the trunk will heat up the backs more. (even though I realize it was sort of a joke). It is possible to set up a bias that puts all the heat in the back brakes, independent of where the wieght is. ABS will handle the balance at the lock threshold.
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Actually it was no joke at all. Weight over the rears will most likely allow the rears to do more work and the car 'hunker down' a bit more as it won't nose dive. You might be surprised. Granted, it's not altering fluid pressure which seems to be your desire.
There is static bias and there is dynamic bias as well. You are chasing static. Try some stiff springs in the front or stiff shocks in the rear- these things will change dynamic bias as well.
Sure, you can gut the stock MC and valve bodies and run full line pressure out back. Better plan on the prop valve or two. And you'll be adjusting it when you have friends in the back seat too- it's that weight thing again.Or if it's raining, snowing, etc.
Want to really take a stab at this then lets fit prop valves in the front. That should prove interesting. You'll of course need two of them- one for each channel. Or would you prefer to Tee them? You can do that too if you like. Forget tha ABS working correctly however.
Other thoughts; source some larger bore calipers for the rear. Not sure what might fit. Buy a larger rear rotor kit (yea, I sell them) or some super sticky rear pads. All will effect static and dynamic bias.
Find some smaller front rotors. Smaller front calipers. Put in junk pads up front. All of this will do the same as the front prop valve in reducing front effectiveness.
Nobody has suggested driving backwards yet...lol (not that one's a joke)
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"Absolut Rara."
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you know, I'm really tired after a long and bad weekend of racing, so I'm not going to make a long-winded reply; but, I'm an OEM brake engineer, and Todd designs and sells high performance brake kits, and we both are heavily involved in various forms of racing; and basically, Todd is right, and you should listen to him.
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Originally posted by Todd TCE:
Actually it was no joke at all. Weight over the rears will most likely allow the rears to do more work and the car 'hunker down' a bit more as it won't nose dive. You might be surprised. Granted, it's not altering fluid pressure which seems to be your desire.
I understand that more rear weight would allow the car to nose-dive less, and put more weight on the rear tires, allowing the rear tires more traction. This would mean there is an opportunity for more work from the rears, but without a brake change, how will they actually do more work? The same amount of pressure will be applied to the pads, and we are assuming that there is no tire slip. This seems to indicate that the rears will not do more work with more weight on them.
I'm not asking questions to prove you wrong, I'm asking because I don't think I understand. I really want to find out how this works, since you seem to be reputable.
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hmm, maybe I should do a quick primer on how brakes and brake proportioning work . . .
The first and foremost thing to remember, is that maximum braking is always limited by how much grip on the road surface the tire has. A tire's grip is controlled by two main factors, the coefficient of friction, and the amount of vertical load on the tire, or basically, how much weight that tire is supporting.
Changing the coefficient of friction can only be done by changing the tire to something different, or driving on a different surface.
Changing the load here is what our discussion is about.
A stock contour is a typical fwd car where the vast majority of the weight is supported by the front tires, even while the car is just sitting there. Because I don't recall the contour #'s offhand, i'll use 70/30 as an example. So, 70% of the vehicle weight is on the front tires, and 30% is on the rear. This means, in the best case situation, the front brakes still can do more than TWICE what the rears can do, regardless of what hardware is being used. Then, when you consider weight transfer during braking the numbers get worse. The actual nose dive of the car isn't a big deal during braking, its the transfer of weight from the rear tires to the front that reduces the effectiveness of the rear brakes. And you should note that, while they are related together, the weight transfer still happens even if you make changes to limit nose dive under braking.
Depending on the initial wieght distribution, and the way the car is set up, you can get so far as to basically remove all load on the rear tires. I've seen photos of even cars like Porsche 911's where the rear tires have actually come off the ground because the weight transfer was so severe (that case was a rear heavy car to start with, but the deceleration rate was high enough to cause the "stoppie").
So it all comes down to what load you have on the rear of the car as to how effective the rear brakes are. If you increase the load at the back of the car, the rear brakes will do more before reaching lockup.
Now for proportioning. For a car that is safe for the public to drive, you need to have a brake system that will never have the rears lock up before the front. If you lockup the rear tires and not the fronts while going through a turn under braking, you will spin the car. To do that, brake designers design in some system to limit the brake torque generated at the rear tires. There are many different methods of setting this bias to the front tires, and some vehicles use several methods, and some use only one . . .
One method is pure hardware sizing. Where the rear brakes are just smaller in general, and capable of less brake torque. This method is pretty common, especially when used in conjunction w/ other methods.
Another is hydraulic system sizing. This is where the circuit controlling the rear brakes is smaller, and provides less pressure and less fluid volume than the circuit for the fronts. Don't confuse this w/ prop valves.
And the final, and most common (in conjunction w/ the hardware sizing) is the use of a proportioning system, that limits fluid pressure to the rears, relative to the front brake fluid pressure. There are hundreds of variations on this, from the simple line restriction like the aftermarket prop valves, to a complex electro-hydraulic unit (the ABS module used for EBD).
An additional prop valve for the rear brakes will never increase braking capability, it will only limit.
Also note that, most if not all fwd vehicles are split into diagonal brake circuits, rather than front/rear like most rwd vehicles.
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Okay, I get how the system works. But from what you say, the system is not dynamic. It provides pressure to the rears that is linearly related to the pressure to the fronts. If you add weight to the rear of the car, both will squeeze harder because it will take more friction to stop the heavier vehicle. However, no tire is running out of traction in this case. I really do get your arguments, I'm just saying that weight will not make a difference in a normal stop. The rears cannot do a different percentage of the work with a different weight balance unless you change the braking system. If you do shift the weight rearward when designing/modding a car, it makes sense to let the rears do more by giving them more pressure, but I can't see how you could change the relative amount of work done by the rear brakes unless you put more pressure to them.
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"Absolut Rara."
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It depends on how the system is proportioned. Not all methods are linear; in fact most aren't, and have at least a knee point and then become linear after that. I don't recall if it was on the contours from the beginning or not, but the later cars have EBD, which uses the wheel speed sensors to decide when to limit line pressure. Also some OEM prop valves are sensitive to weight transfer, like the prop valve in my XR4Ti; and limit pressure as the vehicle pitches forward (a sign of weight transfer).
I guess one of the main points that you are missing is that in a car like the contour, you don't WANT the rear brakes to be doing more, unless you have drastically changed the balance of the vehicle or the brake system proportioning.
A good case in point is the Mustangs our team races. We run larger wilwood brakes up front, because that is what is allowed, but the rears are still stock parts, because the stock parts will provide all the brake torque we can use, even with the race tires, and the modifications we have made to move weight to the back of the car.
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awesome, thanks. I didn't see the dynamics.
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Originally posted by Big Jim:
On some of the Contours, the rear brake pressure bias is controlled by pressure reducing valves in line where the steel brake line connects to the rear brakes hoses for each individual caliper. I wouldn't mess with them unless you like having the car swap ends on hard braking. When these valves act up, they cause that one caliper to not fully release. The valves are different between ABS and non-ABS and are not interchangable.
Thanks Big Jim ..... you are the first who has actually provided any insight into solving the problem. The other posts are interesting, but do not address WHY IS THE REAR ONLY 1% (when it should be 20-30%)
What year Contours have these PRV's? Disk only? Drum only?
If the LF and RR are joined and the RF and LR, that might be useful info. I thought maybe I had excess air the line, but even with air in the rear, that would even out the pressure to the front.
FWIW,
With a newfound search I located from 2/03
"
Late models (I have a late (99 1/2) Contour SE) with ABS use EBD (Electronic Brake Distribution). The ABS controller (Bosch) does this in the ABS module so there is no mechanical proportioning valve in the rear of the car."
Ah - so just what IF I have a bad EBD feature in my ABS?
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Bravo.
And well stated entirely. I didn't get back soon enough and probably could not have put it so well anyhow.
One thing that seems to be a misconception is how most prop valves work, so this might help you better visualize the pressure thing. Most of them work off total pressure. Thus if you put in 600lbs of pressure you get out 600 right? Wrong. This is the kneee Jim is speaking of.
Suppose you have a knee of 450. Now when you put in 400 all four wheels get 400, but when you put in 600 the rears might only get 300. How's that? Well, as the pressure input goes up; the pressure output to the rear goes down. Intentionally. Most factory valves have a preset knee and reduction, they generally just shut down the rears for safe measure. (*the Impala goes from 65/35 to 90/10 under hard braking! And with the weight and wheelbase of this you KNOW there's room for improvements!!)
So what's a manual valve do? It allows you to change the point which reduction occurs. BUT it does it differently than most 'cut off valves' in that it they go up to about 55% reduction total based on the set knee and input pressure. You change where you want it to cut out. Seeing your'e not going this way we'll leave it at that.
Ok. Now you sitll wonder what the hell all of this has to do with those sand bags in the trunk don't you?? With the weight over the rear wheels there is less dive and weight shift is not so quick. So what? Well, as you put in 400lbs of pressure all four wheels brake, as you increase this to 500 all four do some with the rears doing only slightly less...600lbs and they are begining to shut down. Fair enough. Now consider the stock 'nose dive' where the 400-600 input goes up real fast as there is no weight out back to hold down the rear LONGER thus immediate shift places nearly all the work up front.
To this end both shocks, springs, tires, ride height, weight bias and alignment can play on this. That's dynamic braking. What's the magic set up? The one that works best for your parts and car in those conditions operating in.
I'm done, fingers tired. I'll let Jim put in more data and correct any comments he feels I have incorrect. He's the engineer, I just try to improve on what he's done! \\
*excuse my spelling...
Last edited by Todd TCE; 03/16/05 02:10 AM.
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Well....one thought that comes to mind....I know for me to add 200 extra pounds in the trunk to test things would not be that difficult...I'd just throw my old parts that I have already replaced on the car...that'll get you 200 pounds at least!  Bob
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The pressure reducing valves were at least used for the models including 1996 through at least part of 1999. It very well may have been on most if not all models from 1995 all the way to the end of Cougar production in 2002.
It is easy to identify on the car. It is between the end of the steel line and the rubber flex line sort of at the front of the rear wheel well. They are about 2" to 3" long and roughly the diameter of your thumb.
Both drum rear brake cars and disc rear brake cars had them. Both ABS and non ABS had them. The drum and disc systems used the same part number, and the ABS cars had a different part number. I can only guess that the ABS valve must have been able to accomodate the rapid fluctuation of pressure generated during an ABS event. The EBD equipped cars may not have had them, I don't know.
I am not fully aware of the details of how EBD works. I received the service managers overview when Volvo introducted it. Basically it uses the ABS system to control rear brake pressure and can apply the rear brakes much more agressively under some circumstances. On some cars (including the Volvo when it was first introduced) it made a banging noise when in use. The noise was unlike the rapid pounding of ABS, more of a two or three repeat "pop pop pop". When driving cars with EBD I cannot tell the difference between them and a non EBD equipped car.
Other than trying a new set of valves, I would not recommend messing with them. I have driven cars with the rear bias was too high and it can be really dangerous.
The technical information posted by the two brake experts is far more than I can provide.
Jim Johnson
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Originally posted by btrautman:
Well....one thought that comes to mind....I know for me to add 200 extra pounds in the trunk to test things would not be that difficult...I'd just throw my old parts that I have already replaced on the car...that'll get you 200 pounds at least!
Bob
I appreciate the "test it out" spirit of your suggestion - but the "add weight to trunk" idea is not well thought out at all.
The problem has nothing to do with weight transfer, minor changes in spring weights, weight bias etc. It is about rear brakes that BARELY ... yes BARELY work.
If you capped your front brake lines, so had rears only and drove around town taxi like, you would never know anything was wrong. Yet your rear brakes would be excessively hot after many 60% threshold stops.
So how can adding weight to the rear have ANYTHING to do with this problem?
On the limit near ABS use, by all means weight distribution can have big effects. But not when you ae well away from lock up on either end.
BTW - I checked and I don't have any PRV where the steel line means the rubber one.
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I understand your point but have no experience in this matter....I'm just trying to come up with a "functional" use of all these old parts I have......  Bob
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Originally posted by 99fordsvt:
Originally posted by btrautman:
Well....one thought that comes to mind....I know for me to add 200 extra pounds in the trunk to test things would not be that difficult...I'd just throw my old parts that I have already replaced on the car...that'll get you 200 pounds at least!
Bob
I appreciate the "test it out" spirit of your suggestion - but the "add weight to trunk" idea is not well thought out at all.
The problem has nothing to do with weight transfer, minor changes in spring weights, weight bias etc. It is about rear brakes that BARELY ... yes BARELY work.
If you capped your front brake lines, so had rears only and drove around town taxi like, you would never know anything was wrong. Yet your rear brakes would be excessively hot after many 60% threshold stops.
So how can adding weight to the rear have ANYTHING to do with this problem?
On the limit near ABS use, by all means weight distribution can have big effects. But not when you ae well away from lock up on either end.
BTW - I checked and I don't have any PRV where the steel line means the rubber one.
Ok. So cut to the chase. You don't want to hear all the mumbo-jumbo data we have offered you. That's fine, we can handle rejection~! lol
Stop wasting your time here reading all of this and do the following:
Pull the calipers and rebuild or replace them.
Lube the slider assemblies properly.
Replace the rubber hoses. (looking for debris in them)
Inspect all hard lines for kinks.
Flush the hell out of the lines and even blow them out to be sure.
Turn the rotors nice and pretty.
Put in some new pads.
In the end, if it works and you're happy with the results you'll know what the problem was- lack of maintenance. On the other hand if it works just like before; call me and I'll sell you a 11.75 rear rotor replacement and you can elevate the rear bias.
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Originally posted by 99fordsvt:
I just replaced both rear calipers, probably unecessarily. They are bleed and have new pads and rotors.
FWIW I had the same symptoms before changing all the components. Fluid does squirt out during bleeding, but not super strong. I ordered some Powerbleeders - can't hurt but probably won't help.
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"Absolut Rara."
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so, let me get this straight, you want to know why your rear brakes are working normally? and refuse to believe any explanations of how they work normally? and still insist that something is wrong, because your rear rotors don't get as hot as the front rotors?
And you have the balls to insist that I don't understand what is going on? all based on your excessively scientific thermal data gathering technique of throwing snow on the rotors?
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rara, what exactly made you think that just because you are an oem brake engineer who is actively involved in racing you are not only qualified to speak here but infact know what you are talking about? and do you honestly think that your fancy schmancy science can hold water compared to his snow on the rotor method of analysis? j/k hahahaha
seriously though, thanks for all of the good info in the thread todd, jim and rara. the rest of us have found it rather educational.
00 black/tan svt, #2052 of 2150, born 2/1/00
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Originally posted by 99fordsvt:
Ah - so just what IF I have a bad EBD feature in my ABS?
Hey Rara, Todd and Jim
have you ever in your years of experience with brakes ever seen anything go wrong with ebd or any other kind of bd system?
Call me 
but im gonna go out on a limb and guess no. Just a guess though.
98 csvt t-red.. sho-shop intake, b&m, fidanza, spec1 clutch, Torsen, DMD,optimized Y& TB, Brullen, rear strut bar,h&r's,17" konig traffik's.
"I say what I mean and I do what i say"
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Originally posted by my csvt:
rara, what exactly made you think that just because you are an oem brake engineer who is actively involved in racing you are not only qualified to speak here but infact know what you are talking about? and do you honestly think that your fancy schmancy science can hold water compared to his snow on the rotor method of analysis? j/k hahahaha
seriously though, thanks for all of the good info in the thread todd, jim and rara. the rest of us have found it rather educational.
Rara, Run for President and you don't have to be qualified in a damn thing and there would be many people willing to listen to you!
Bob
An ounce of prevention provides a pound of cure!
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Originally posted by dubkatz:
Originally posted by 99fordsvt:
Ah - so just what IF I have a bad EBD feature in my ABS?
Hey Rara, Todd and Jim
have you ever in your years of experience with brakes ever seen anything go wrong with ebd or any other kind of bd system?
Call me
but im gonna go out on a limb and guess no. Just a guess though.
No
Jim Johnson
98 SVT
03 Escape Limited
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Originally posted by Rara:
so, let me get this straight, you want to know why your rear brakes are working normally? and refuse to believe any explanations of how they work normally? and still insist that something is wrong, because your rear rotors don't get as hot as the front rotors?
And you have the balls to insist that I don't understand what is going on? all based on your excessively scientific thermal data gathering technique of throwing snow on the rotors?
RARA,
Take a pill man. RE-read some posts. Your ego is all tangled up in your short hairs. Please show me WHERE I insisted that you don't know what is going on overall with braking systems?
Here's my key early statement that maybe you should re-read
"Thanks - I certainly realize that the fronts handle a majority of the braking (>70%) but that fact doesn't mean a case can't arise where the backs are still far under-biased from where they should be."
But you can tell somehow that my braking system is normal and know there is NEVER a case where a vehicle has far under biased rear brakes. Uhhh ........
I basically said that "thanks for the interesting posts" but they don't pertain to my specific thread starting problem that occurs FAR UNDER threshold (on the limit of lockup) braking.
Your posts and several others were all about weight transfer and such that is important at high braking levels, but not a significant factor at low braking levels that I still experience my braking issue at. Why isn't that clear?
I said straight up that I didn't have an IR temp gauge. Please take a poll of how many CEG'ers do. But I do own a few 4 wheel disk brake vehicles and NONE of them have the observable massive temp difference from front to back that I have on my CSVT. YES - I said all of this earlier.
But now I am a dumba$$ because "my brakes are working correctly" and I don't know it. Well then please tell me why other 4 wheel disk vehicles I've checked are much closer to balanced on temp? They must not be the normal ones?
OK - let's hear your professional braking engineer explanation of that?
And laugh all you want but an audible sizzle at least tells you the the temp is above a key level. Whereas I know the back was only 110-120 deg F max. This is about a major rear braking deficiency, not the fine tune situation you led the thread to.
When fine tuning - of course use the right tools. When searching initially for a major imbalance, more crude tools are still informative. Sorry for not first showing up to the forums with my IR and wireless type K thermocouple 18 bit A/D data sampled at 150 Hz during laps at Waterford with 18 blindly picked test drivers. This was an initial get ideas thread and you turn it into an ego blabbing insult fest.
Being an engineer - you should know better.
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"Absolut Rara."
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ok, let's try this again then.
First, what vehicles are you comparing against?
What pads are you running in those vehicles, and what are you running in your contour, both front and rear? Different vehicles have completely different brake system designs, with normal operating temps varying from ambient to over 900 *F under typical usages. Just because they are different from another vehicle doesn't mean they are bad.
Also, your "sizzle" test does not necessarily indicate a problem at all. you say 110-120 *F max, but water/ice doesn't boil or "sizzle" until 212 *F . . . further, how is the system performing? Does the car stop properly?
I hate to "brake" it to you, but it still is all about weight transfer and axle loading whether its a .3g stop or a 1.0g stop. If there is little wieght on that axle, those brakes will do little work, and won't get very hot. It's simple physics.
You are taking an extremely inaccurate test and comparison, and using it to demand an explanation of what is wrong with your brakes when there very likely isn't anything wrong. And when you do get an explanation, you dismiss it, and throw a hissy fit becuase no one is giving you the answer you want to hear.
Tell you what, you bring your car over to my house, I'll grab an IR temp probe, and we can do a back to back comparison of your contour and mine for rotor temps after similar stops. Would that make you happy?
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Originally posted by Rara:
Also, your "sizzle" test does not necessarily indicate a problem at all. you say 110-120 *F max, but water/ice doesn't boil or "sizzle" until 212 *F . . . further, how is the system performing? Does the car stop properly?
Like I said - Re-read the posts.
From me:
"I think I have a major brake bias problem on my 99 SVT. After a hard stop, I can touch the REAR rotors and they feel maybe like 110 deg F. The FRONTS are nearly smoking hot (pretty technical eh?) and sizzle when snow is tossed on them. I wouldn't dare touch them."
Exactly my point - the REARS are about 110F and the FRONTS sizzle, which you say (and I don't disagree) is above 212F.
Ah - so now you aren't dissing the sizzle test so much after all with that major temp difference, huh?
"Hissy fit" if the shoe fits, but frankly I'm not waiting for a certain answer - just the one that effectively solves the problem.
Jeez - you are one confrontational guy, at least tonight.
Hope we can patch things up because before you didn't seem so bent on flaming people who were honestly just looking for solid info to resolve a problem.
I dare not say spew any more data or vehicle types until I gather some reliable data - I might get flamed. But I maintain I still have the problem below 0.3g, so don't continue on your weight transfer rant.
The car stops very crappy - very slightly pulling to the right.
But good suggestion to compare to another Contour. I know another car (3.0 like mine, not that it matters) to try it on.
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"I dare not say spew any more data or vehicle types until I gather some reliable data"
Hell, why start now?
Please let this man's foolishness fade to the bottom of the pages...I'll promise not to even read it any more.
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Great - so at least we have one "brake expert" off this thread.
This is unbelievable - a guy tells you that his plane is missing a chunk of one wing, and you launch in a treatise of how all planes yaw slightly due to non-linear aerodynamic loading - that you are the experts, his wing is fine, and how he should shutup, at least until he provides CMM data of a wingscan.
Your recommendation was to put new rotors pads and calipers on the car when I stated right up front that I had already done that.
I've got an idea - since 80% of braking and temperature rise is in the front, maybe the rears could be downsized a bit (saving cost and weight) then maybe the temps would be slightly more equal? ..........hmmmmm
(of course they are downsized in the rear and temps should at least in the same ballpark)
Being a brake expert, he obviously had all those IR brake temps on hand from Contours to share with us all. Instead I'm told to add weight in my trunk so the rear will "Hunker down" ..... now that is technical. Bad brakes? "add some weight" .... great advice TCE.
TIMEOUT guys - When is it a CEG crime to come for help to the forums (and try to keep the topic on track) when your back brakes aren't working even close to right?
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Alright... I am not a brake expert.. (and those "self proclaimed ones aren't SELF proclaimed.. they ARE...)
HOWEVER.. I HAVE read.. re-read, and triple read the posts you made.. and still don't get why you are confused..
Rear brakes do near none of the work.. you admit to <30%... others say <10 or even less than that..
Your REAR rotors are 110-ish.. you say... and fronts, at least 212... okay.. so.. if the rears do near nothing.. and the fronts: most of the work.. WHY IS IT NOT NORMAL for the fronts to be MUCH hotter?..
I have an IR probe here, (my father does, actually... and I took the liberty of doing those test runs for you.
98.5 SVT
4 wheel disc (for purpose of data.. obviously svts have all disc)
Temperature of rotors before each run 62-64�ºF
Temperature: 55�º
Run 1
10mph
82.2/83.2/78.0/78.9 (FL/FR/RL/RR)
Run 2
20mph
96.0/96.6/83.1/82.8(FL/FR/RL/RR)
Run 3
50mph
218.5/221.6/111.4/112.8 (FL/FR/RL/RR)
The rotors started off at air temps, but I drove and heated them, then allowed them to cool to 62�º before beginning my run.. that was my controlled temp.
All of these runs were done at "moderate stopping rates" of an ~.5G or so. I know this isn't your <.3G perfect scenario.. but I did this JUST to see what you would have to say... All runs were cooled between with 30 minutes of non-use and ambient temperatures were returned.
Now.. as a side question.. Why does my car exhibit a slightly higher temp on one side (Right side...) when braking? I feel no pull, and it stops straight....
DISCLAIMER: This test is in no way scientific, or mistake-free.. merely an attempt at creating something more concrete than snow...
Ray
Last edited by Ray; 03/18/05 05:33 AM.
'99 CSVT - Silver #222/276
In a constant state of blow-off euphoria.
Originally posted by Kremitthefrog:
I like to wear dresses and use binoculars to watch grandmas across the street.
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Ray,
Thanks, great work and it proves the "without data you are only an opinion" cliche.
While I believe your test was useful, it would also be useful to check them after 30 minutes of stop and go city driving. The early temps from ambient (as you tested) are likely to be dominated by heating the rotor's thermal mass, than representative of the steady state temp after saturation when only convection and to a lesser extent radiation (RARA isn't the only Engineer around) determine resultant rotor temp.
I expect differences to be dramatic - probably raising the front vs. rear temp delta even higher that your initial tests.
My only question is "What if I repeat your test (which I have to now), and get 330 F fronts and 75 F rears, instead of your 218F and 110 F nominally?
Underbiased rears (from where they SHOULD be) for me maybe?
Hmmmm..... maybe I can go to the CEG forums and be flamed trying to get some ideas then.
I don't really dispute the "expert" status of those you refer to as their earlier proportioning posts are informative, but how can their advice on this particular item be "expert" if they obviously haven't even read the situation (new parts initially, thinks I said 110F sizzled). Kind of like a Judge who can give the expert verdict before hearing the evidence.
I've never been confused on the fact that most cars have higher front brake temps. I buy it. Also all the load transfer stuff from even TCE. Great stuff. I'm not confused at all.
In only the second post here I said:
"Thanks - I certainly realize that the fronts handle a majority of the braking (>70%) but that fact doesn't mean a case can't arise where the backs are still far under-biased from where they SHOULD be."
Key word SHOULD.
Thanks again.
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this is the ultimate "beating a dead horse thread"
No matter who and what is said this guy still thinks something is wrong, so let him think it.
98 csvt t-red.. sho-shop intake, b&m, fidanza, spec1 clutch, Torsen, DMD,optimized Y& TB, Brullen, rear strut bar,h&r's,17" konig traffik's.
"I say what I mean and I do what i say"
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"Absolut Rara."
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Originally posted by 99fordsvt:
In only the second post here I said:
"Thanks - I certainly realize that the fronts handle a majority of the braking (>70%) but that fact doesn't mean a case can't arise where the backs are still far under-biased from where they SHOULD be."
Key word SHOULD.
Thanks again.
Brake bias needs to be developed to handle the WORST case scenario; you absolutely never want to lock the rears first.
You are basing your opinion of what they "should be" on extremely limited information. Further, the ratio of rotor mass relative to the amount of work done is a lot higher in the rear so naturally temps are going to be lower.
I think Ray did a great job w/ his test there to show that what you are seeing is perfectly normal; his measurements correlated very will w/ your "tests".
You keep accusing people of not reading your posts. but you seem to just not follow what people are telling you, I don't know if its becuase you aren't reading them or what.
You liken it to a pilot saying a chunk of wing is missing, and people saying its fine, its not, its more like there isn't a chunk missing and you think it is.
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Originally posted by 99fordsvt:
Ray,
Thanks, great work and it proves the "without data you are only an opinion" cliche.
...My only question is "What if I repeat your test (which I have to now), and get 330 F fronts and 75 F rears, instead of your 218F and 110 F nominally?
So, go ahead & run your test. Then we'll know.
Once you're done, if the temps are way out of wack, grease up those slide pins & try it again.
Must be that jumbly-wumbly thing happening again.
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OK - of course I was eager to get some real measurements and today I tracked down an Omega IR temp sensor. Unfortunately I only had about 20 minutes in my schedule to play with it.
As expected, it is quite sensitive to minor aiming angle changes, and the longer you wait for the highest reading, the longer the other rotors have to cool off.
Here are the results so far:
Start (sitting for about 45 minutes after a 10 minute drive in about 30-35 degree F ambient)
LF 50 RF 48
LR 35 RR 32
One moderate stop from 50 mph:
LF 98 RF 106
LR 53 RR 54
3-4 minutes of city stop/go:
LF 283 270
LR 128 110
15 seconds of dyno braking - steady 30 mph
LF 450 RF 350 (poor aim?)
LR 280 RR 175
You can easily see the cooling effects since I started measured the rotor skin temp at the LR, working clockwise.
There is a fairly large degree of operator error I believe, maybe even 50 deg depending on the exact target.
OK - initially the temps are apart quite a bit, but not as much as I'd expected based on earlier observations. Flame away if you must. But I really think my normal 40 minute drive cycle is required first. And that is when I first noticed the larger temp differences (and again later today).
Either way - the car still stops like crap and pulls to one side.
I'm leaning towards a need for a complete bleed job. I can't really make solid conclusions until I test a friends CSVT driving the same cycle as me. And of course there is the possibility that all CSVT's just have way too much front bias (for track needs).
Ahh - some real data, six days later.
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I see no reason to flame away..
That was objective, and unbiased, and even admittedly inaccurate on your part perhaps, so that was very honest...
I think people will see that... /Besides, things happen. You obviously had less time to cool between runs, and perhaps stopped harder.. I didn't do ANY hard stops such as your last one, and the differences could be shown in the relative temps you had vs. mine.
Either way.. pulling one way or another could be a bleed job, slider pins, or bushings in the control arm, etc..
Good to see some hard data on the car in question, either way.
Ray
'99 CSVT - Silver #222/276
In a constant state of blow-off euphoria.
Originally posted by Kremitthefrog:
I like to wear dresses and use binoculars to watch grandmas across the street.
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i just reread your posts in this thread and i have a couple questions for you. you think you have a problem with the rear brakes due to the rears operating at a cooler temp than the fronts and because the brakes are generally "crappy" in feel, correct? aside from the temp difference, what leads you to think the rears are the guilty party?
what i mean is... the brakes on my new tour check out as being in fine shape even though they aren't as effective as those on my last csvt, an early 99. i happen to know the difference between the two cars is due to better front pads, braided steel lines and fresh properly bled pretty ok fluid. since you have already maintained/repaired/replaced the rear parts you may want to expand your search. just a thought.
00 black/tan svt, #2052 of 2150, born 2/1/00
formerly known as my csvt
"Nothing in the world is more dangerous than a sincere ignorance and conscientious stupidity." -Martin Luther King, Jr.
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Originally posted by Rara:
I hate to "brake" it to you, but it still is all about weight transfer and axle loading whether its a .3g stop or a 1.0g stop. If there is little wieght on that axle, those brakes will do little work, and won't get very hot. It's simple physics.
You really believe that even at <=0.3 g? Hey - as long as the you aren't locking up any wheel (front or rear), you can dial the brake bias wherever you want it and put the heat there. It has nothing to do with WHERE the weight is in that case.
0.3 g, 100% rear brake bias, no tire lock up, all heat in the rear brakes, 70% of weight in the front =
0.3 g, 100% rear brake bias, no tire lock up, all heat in the rear brakes, 30% of weight in the front
Simple physics ...
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"Absolut Rara."
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Originally posted by 99fordsvt:
Originally posted by Rara:
I hate to "brake" it to you, but it still is all about weight transfer and axle loading whether its a .3g stop or a 1.0g stop. If there is little wieght on that axle, those brakes will do little work, and won't get very hot. It's simple physics.
You really believe that even at <=0.3 g? Hey - as long as the you aren't locking up any wheel (front or rear), you can dial the brake bias wherever you want it and put the heat there. It has nothing to do with WHERE the weight is in that case.
0.3 g, 100% rear brake bias, no tire lock up, all heat in the rear brakes, 70% of weight in the front =
0.3 g, 100% rear brake bias, no tire lock up, all heat in the rear brakes, 30% of weight in the front
Simple physics ...
You seem to be missing the fact that a vehicle may not even be capable of performing a .3g stop with 100% rear bias. If there isn't enough load on the rear axle, it may lock the axle long before reaching a given decel rate.
Further, overall temps have a lot more factors involved than just bias. System mass, and cooling have a lot more effect than bias on overall temps.
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You're a patient man, Rara. I bow to thee.
Pacific Green '96 Contour LX V6
â??98 GTP, light mods, 14.66/94
Calypso Green '92 Mustang LX coupe, 13.56/101
Crown Autocross Club 1999 Street Tire Champion, 2000/2001/2002 Street Modified Champion
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"Absolut Rara."
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Originally posted by MFE:
You're a patient man, Rara. I bow to thee.
I think I'm going to have to start writing my posts as if I were explaining things to a chainlink fence. It actually might be easier.
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At least you are talking some sense now. I agree with your cooling and thermal mass comment though in this case they are closely balanced enough that I believe bias is the culprit here.
Apparently you didn't see or understand the "as long as the you aren't locking up any wheel" part of my message.
Most Cg / weight distributions combinations on the road can easily get to 0.3g without locking the rears. Prove me wrong.
So you are at least admitting that where the weight is in the vehicle isn't ANY factor in determining where the energy is disappated (at braking levels below tire lock up, again).
You are going to think this is all non-sense, but it actually is material in the "knee" in the bias curve that TCE brought up.
For example, you could have a setup that overheats the rears in low braking conditions, but still under-biases (correctly) them in panic stops. I'm not saying my vehicle has that condition, though.
As to the choir support, it is funny how easily they overlook your mistatements to flame those making a valid correction.
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Originally posted by 99fordsvt:
At least you are talking some sense now.
Yeah I just HATE it when TCE and Rara fill the boards with their mindless b.s.
Originally posted by 99fordsvt:
As to the choir support, it is funny how easily they overlook your mistatements to flame those making a valid correction.
WTF did you correct? The temp discussion was supported by your own data! The weight transfer theory is very valid; go yank the handbrake on a civic and see what happens.
-- 1999 SVT #220 --
In retrospect, it was all downhill from here. RIP, CEG.
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Originally posted by 99fordsvt:
Apparently you didn't see or understand the "as long as the you aren't locking up any wheel" part of my message.
Most Cg / weight distributions combinations on the road can easily get to 0.3g without locking the rears. Prove me wrong.
What did I correct?
Well I guess I have to spell it out for you again. Whether you have 70%, 80, 90 or 95% front brake bias, adding weight to the rear won't "make the rears work any harder", It just doesn't matter where the weight is added for normal low level braking (as in the city driving case where I notice the grossly mis-balanced temps).
Any clearer? Your pull the parking brake analogy is senseless. Big braking well over 0.3 G, unload the rears and locks them, as expected. What is the point?
Did I ever say weight transfer doesn't happen? NO
I think the point is that you can have the brake bias set too much to the fronts, and overheat the fronts (as compared the rears) in city stop/go, even is the bias is OK for panic stops.
Where the weight is under that (<0.3g) situation is totally a non-issue, contrary to TCE and RARA's gospel.
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"Absolut Rara."
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Originally posted by 99fordsvt:
Where the weight is under that (<0.3g) situation is totally a non-issue, contrary to TCE and RARA's gospel.
Except the situation you discuss is totally irrelevant. 0.3g is a pretty normal traffic stop rate, anything less and you could nearly use your tennis shoes to generate the braking effort.
If you are locking the tires under 0.3g, then you either need some tires that aren't made out of teflon, or get off the ice.
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Originally posted by 99fordsvt:
But I really think my normal 40 minute drive cycle is required first. And that is when I first noticed the larger temp differences (and again later today
You say 0.3g is irrelevent.
Of course, for anything related to maximum braking it is.
But to the big temp difference I observed, it is not.
- 0.3g and below is around a normal city stop, agreed.
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"Absolut Rara."
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Originally posted by 99fordsvt:
Originally posted by 99fordsvt:
But I really think my normal 40 minute drive cycle is required first. And that is when I first noticed the larger temp differences (and again later today
You say 0.3g is irrelevent.
Of course, for anything related to maximum braking it is.
But to the big temp difference I observed, it is not.
- 0.3g and below is around a normal city stop, agreed.
0.3g IS irrelevant for the temperature discussion that started this thread. The temps measured for BOTH front and rear are incredibly low, and far from the capacity of the system. If you set the bias to maximize the use of the rears in very low effort situations, you simply end up having the bias way off at higher effort stops, resulting in a car that is dangerous to drive.
You are frustrating the hell out of me, because you are ignorant and argumentative. If you want to learn how brake systems work, great, we'll hold a class; but if you want to argue your ignorance, and refuse to give up when shown wrong, go someplace else. How many vehicles out on the road have brake parts that you designed or otherwise worked on? Let me know when you have more than I do, or at least when you have one.
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"You can lead a horse to water but then you still have to deal with the horse's ass." Or something. Maybe it's "you can lead a horse to water but it can't drink when it's choking on its nuts". Nah, that's not quite it either..."A fool and a keyboard are a dangerous combination"...meh..."there's a sucker born every minute, and then he buys cross-drilled rotors"...no that isn't it either. Damn. I'll have to think about this for a while. Maybe it's "your steadfast refusal to absorb even one bit of the useful information given to you on a polished silver platter by industry experts while stubbornly arguing a ridiculous case indicates you really belong on ClubGP.com". Yeah, that's it. Whew.
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â??98 GTP, light mods, 14.66/94
Calypso Green '92 Mustang LX coupe, 13.56/101
Crown Autocross Club 1999 Street Tire Champion, 2000/2001/2002 Street Modified Champion
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 This thread is completely useless. Rara should post how brakes work in the FAQ, and delete this drivel. I don't see all the arguing here being necessary at all. They are friggin' brakes FCOL. Metal thingies to make a car stop. This kind of bickering belongs in CI, in those stupid oil threads.
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If the clown wants the car to swap ends next time his stands on the brakes, then fine let him increase the rear bias, and end up facing oncoming traffic. Talking to him is pointless, as he is ignoarant and argumaetative. If you're pissed at the brake wear and/or fading/warping, I've got an idea...use better f$#king brake componenets other than OEM!  Alternatively one-up that and upsize the fronts. Increasaing the rear braking strength which allows the rears to lock will increase the chance of instability in a panic stop - remember this: A ROLLING TIRE HAS MORE TRACTION AND CONTROL THAT A SKIDDING TIRE  What this means is the if you lock the fronts and the rears keep rolling (which would only happen if the re is no ABS or it failed) then you would lose steering, increase the stopping distance BUT you'd still go straight and not spinning off into a ditch and killing yourself and others. Luckily ABS (which most of us have) reduces the front skidding, which although may not reduce stopping length DOES allow the driver to STEER the car, as only rolling tires steer! If the rears lock before the fronts, the fact that they will have a lower coefficient of friction now, will undoubtedly unsettle the car and cause it to spin - thus you lose control all together and swerve/crash. Not very ideal huh? Now if you want to argue this - well my freind you're a nimrod and you know not of what you speak. 
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
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A lack of planning on your part does not constitute an emergency on mine!
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"Absolut Rara."
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tell us how you really feel Stazi
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Is it time to re-elect the President yet? That was the last time I have seen all this good-will being spread around!!!
Bob
An ounce of prevention provides a pound of cure!
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Originally posted by Stazi:
If the clown wants the car to swap ends next time his stands on the brakes, then fine let him increase the rear bias, and end up facing oncoming traffic.
Bravo! You've just indicated that you don't know what the HeII the thread is about.
It is about a vehicle with rear bias well BELOW what it is supposed to be. So to add rear bias (or preferably fix whatever is causing the gross underbias) would put it back to NORMAL!
Nice 1+1 = 2 post of yours, but I never disputed those braking 101 items. Why you bring them up is mysterious to me.
I plan to borrow the IR temp gauge again soon and do more testing. Here are some comparisons from other vehicles:
http://www.zeckhausen.com/testing_brakes.htm
Hey - whatdayaknow - all those rear brakes in the test are above the "sizzle temp"
The know it all flamers who can't comprehend obviously know the outcome beforehand and that all Contour brake systems are faultless and NEVER NEVER NEVER underbias the rear .... NEVER.
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why don't you just buy a new one of whatever part(s) it is that control brake bias and see what if anything changes. if nothing changes then there you have it. if something does change then come back and tell us.
00 black/tan svt, #2052 of 2150, born 2/1/00
formerly known as my csvt
"Nothing in the world is more dangerous than a sincere ignorance and conscientious stupidity." -Martin Luther King, Jr.
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Originally posted by 99fordsvt:
Originally posted by Stazi:
If the clown wants the car to swap ends next time his stands on the brakes, then fine let him increase the rear bias, and end up facing oncoming traffic.
Bravo! You've just indicated that you don't know what the HeII the thread is about.
It is about a vehicle with rear bias well BELOW what it is supposed to be. So to add rear bias (or preferably fix whatever is causing the gross underbias) would put it back to NORMAL!
Nice 1+1 = 2 post of yours, but I never disputed those braking 101 items. Why you bring them up is mysterious to me.
I plan to borrow the IR temp gauge again soon and do more testing. Here are some comparisons from other vehicles:
http://www.zeckhausen.com/testing_brakes.htm
Hey - whatdayaknow - all those rear brakes in the test are above the "sizzle temp"
The know it all flamers who can't comprehend obviously know the outcome beforehand and that all Contour brake systems are faultless and NEVER NEVER NEVER underbias the rear .... NEVER.
Yeah and you're SOOOOOOO analytical with your whole argument based on the sound some snow made when you threw it on your rotors. You're ridiculous. How did you come up with your imaginary bias proportion? How do you know it isn't 70-80-90-95%?
Stop trying to act like you're in some sort of divine connection with your braking system.
Without ACTUAL brake pressure readings on each wheel, you CANNOT make the assumptions you have made. Temps won't tell you enough due to the different sized rotors, front to rear. You need to know the pad pressure, coefficient of fricton of the front and rear pads and actual contact area.
So if you measure the temps, what kind of home-brew calculation will you use to deduce that your brake roportioning is wrong? Do you have access to the original DVP&R for the CDW-27 Brake Design?......... somehow, I think NOT!
Eh, f@#k, do what the hell you want you are a lost cause.
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!
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"Absolut Rara."
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Originally posted by 99fordsvt:
I plan to borrow the IR temp gauge again soon and do more testing. Here are some comparisons from other vehicles:
http://www.zeckhausen.com/testing_brakes.htm
Hey - whatdayaknow - all those rear brakes in the test are above the "sizzle temp"
The know it all flamers who can't comprehend obviously know the outcome beforehand and that all Contour brake systems are faultless and NEVER NEVER NEVER underbias the rear .... NEVER.
First, Hey, "whatdayaknow" all the cars in those tests were rwd, had completely different setups, and were being tested beyond some normal stop and go OF COURSE THEY WILL HAVE HIGHER REAR TEMPS
And the "know-it-all-flamers" aren't saying a contour could never be under-biased; only that yours doesn't have a problem based on the information you have provided.
You don't seem to understand that in some conditions the rear MUST be underbiased in order to prevent overbias in other conditions. Overbias in the rear = very bad and dangerous. Please get this through your thick skull and quit clogging up my board.
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2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!
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The flawed premise is that the brakes are functioning normally other than the rear bias. THEY ARE NOT.
You're getting uneven front temps, and the brakes pull to one side. That's not a problem with the rear brakes, it's a problem with the FRONTS.
It ain't rocket science; any self-respecting semi-literate home mechanic would have shut off the computer days ago and gone back through the front [censored] brakes looking for problems associated with either a sticky caliper, air in the system, or an internally damaged flex line restricting the fluid back-flow when the brakes are released.
When it's the middle of winter and your hose is too warm inside, do you turn on the air conditioning instead of turning down the furnace? Do you switch cereal brands because the milk is spoiled? Do you buy new glasses instead of simply cleaning the TV screen? I mean God DAMN. KISD...Keep It Simple, DUMBASS.
Pacific Green '96 Contour LX V6
â??98 GTP, light mods, 14.66/94
Calypso Green '92 Mustang LX coupe, 13.56/101
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Originally posted by 99fordsvt:
Bravo! You've just indicated that you don't know what the HeII the thread is about.
Actually, he wasn't indicating anything of the sort.. He was stating that, according to the current data at hand, nothing seems unbiased, and if you DO increase rear bias then it would not be "back to normal" it would, indeed, be higher... so you'd be a spinner.
You are correct, if it WERE lower and you raised it, it would fix the problem, but to raise the rear bias when you haven't got CONCRETE proof that its off, is simply crazy. Just because those temps are lower doesn't mean anything. As stated, larger front rotors, and more contact area in the front make anything but an ACTUAL pressure reading simply a "Guess", at best (even IR temps, as we both performed..)
This is just their (much more aggresive) way of telling you that increasing the rear bias when going on nothing more than a hunch and IR temps is not a good thing to do...
It is much simpler, and more cost effective (not to mention safer) to diagnose the fronts, replace anything you may have missed (even though you just worked the fronts over) and then move to the rear, looking more in depth for sticking parts, etc, etc.
The fact that you just replaced all the braking components recently and then you have a problem show up seems to point to the fact that something may be wrong (air let in the system, etc, etc..) but it could be absolutely ANYTHING...
If your car pulls to any side while braking it is the fronts you need to worry about. (with the obvious exceptions of bushings, and LCA's being worn, etc.)
This thread has gone on MUCH too long.. How about you start looking in to the fronts a little more, and then move to the rears, and let us know what parts are worn (or broken), if any. Don't assume since they are recently checked that all is well...
Ray
'99 CSVT - Silver #222/276
In a constant state of blow-off euphoria.
Originally posted by Kremitthefrog:
I like to wear dresses and use binoculars to watch grandmas across the street.
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Rara and Stazi work with brakes prolly every single day. If anyone on this entire site knows what they are talking about, it is these two.
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Let me try and restate the original poster's statement:
"It seems to me my rear brake is working less efficient than the fronts because given the proportioning in my car, the rears are far cooler than the fronts. Ideally the rotor temps should be more even in all situation for best efficiency."
Does this paraphrasing capture the thought?
I read through the whole post with interest because I thought I saw misinterpretation what was said and a lot of frustration as the result.
I'm interested in this from engineering point of view as equal temperature must be one of the holy grail for brake system designer.
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Originally posted by TSIN03SE:
Does this paraphrasing capture the thought?
Yeah, it captures the original intent, but leaves out the willful ignorance that follows.
Pacific Green '96 Contour LX V6
â??98 GTP, light mods, 14.66/94
Calypso Green '92 Mustang LX coupe, 13.56/101
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Tony, you're righ in your transaltion. But How can you ASSUME that temperatures should be equal on the front and rear rotors? You simply cannot do that, especially after a panic stop as the rears will NEVER do as much work as the fronts and therefore will NEVER reach the same temperature.
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!
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Originally posted by Stazi:
Tony, you're righ in your transaltion. But How can you ASSUME that temperatures should be equal on the front and rear rotors? You simply cannot do that, especially after a panic stop as the rears will NEVER do as much work as the fronts and therefore will NEVER reach the same temperature.
exactly...I would hope that the rears would NEVER get as hot as the fronts on a stock setup under heavy braking.
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Originally posted by Stazi:
Yeah and you're SOOOOOOO analytical with your whole argument based on the sound some snow made when you threw it on your rotors. You're ridiculous. How did you come up with your imaginary bias proportion? How do you know it isn't 70-80-90-95%?
Stop trying to act like you're in some sort of divine connection with your braking system.
Without ACTUAL brake pressure readings on each wheel, you CANNOT make the assumptions you have made. Temps won't tell you enough due to the different sized rotors, front to rear. You need to know the pad pressure, coefficient of fricton of the front and rear pads and actual contact area.
So if you measure the temps, what kind of home-brew calculation will you use to deduce that your brake roportioning is wrong? Do you have access to the original DVP&R for the CDW-27 Brake Design?......... somehow, I think NOT!
Eh, f@#k, do what the hell you want you are a lost cause.
Well if you could comprehend, maybe you saw a few IR temp readings that I posted. You don't need a tire pressure gauge to initially tell you have a totally flat tire ( well maybe you do), and if I can drive home, flat palm my barely lukewarm rear rotors yet not even dare to touch the fronts, that tells me something just may be off.
So I follow it up less than a week later with IR temps and you can't get it through your thick skull!
You obviously have a divine connection with your a$$hole.
BTW - temps tell plenty since this whole entire thread is about a GROSS temp mismatch. Again - let it soak in. It is only in like the heading "99% front brakes".
Not "64 vs 55" ... but 99 (that is the number just below 100 as in "100% a$$hole").
Where's all of your data Mr Analytical?
Look through the posts - you unecessarilly threw the first rocks.
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Originally posted by TSIN03SE:
"It seems to me my rear brake is working less efficient than the fronts because given the proportioning in my car, the rears are far cooler than the fronts. Ideally the rotor temps should be more even in all situation for best efficiency."
Thank you! If it wasn't for Big Jim, Ray and you, I was beginning to believe that all CEG'ers on this thread were ego stroking OEM brake engineers without any reading comprehension skills.
Somehow they think that I'm insisting on unecesarily turning up my rear bias (not that it is currently adjustable). I'm really just looking for the cause of the imbalance adn fix it, leaving the system OEM. Still most likely some difficult to purge air is my guess.
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I havenot had internet access for the last few days so forgive me if I missed something on this thread when I tried to catch up.
Last I remember someone posted some temp readings from his car then 99fordsvt found an infared thermometer and found similar readings.
Did something else happen, or is 99fordsvt falling back to his original premise?
Jim Johnson
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03 Escape Limited
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The temps weren't mis-balanced super bad from the few sample stops I tried with the IR temp gauge. But I need to repeat the test after a longer drive cycle. Early indications are that the bias is nearly 100% front at light braking, but closer to correct under heavy braking.
Hey - this could be entirely OK for this vehicle, but I still have to verify. I have a slight pull to the right, but that is tiny compared to this major imbalance.
It still remains that after my 40 minute drive home, the rears are lukewarm (110 ish), and the fronts 450+. When I get possession of an IR guage again I can confirm all of this.
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Please measure and post your results. I'm curious.
Stazi, I had this ideal for awhile. If contours are equipped with ABS, then we can eliminate the prop valve(some are built-in to the ABS module). This way the knee point isn't static but dynamic. It truely would be fully dependent on the dynamic weight transfer and available traction at each axle. This way we extract the max efficiency from the brake system.
This assumes the rears are corrected sized to be in the ball park of factory weight balance.
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That would be a VERY expensive experiment and I'm not sure if it would wig out the ABS. After all, is it a 2 or 4 channel ABS system?
Honestly, I wold not want more bias towards the rear anyway and having a flaoting knee would allow for too much of a possibility of rear lock-up. To a good driver this would be tolerable. To your average kid, recipe for disaster.
2000 SVT Turbo 295hp/269ftlb@12psi
#1 for Bendix Brakes Kits!
Knuckles rebuilt w/new bearings $55
AUSSIE ENDLINKS $70
Gutted pre-cats $80/set
A lack of planning on your part does not constitute an emergency on mine!
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Hmmmm, I wonder what Terry Haines would make of all this...........
Bob
An ounce of prevention provides a pound of cure!
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Originally posted by 99fordsvt:
The temps weren't mis-balanced super bad from the few sample stops I tried with the IR temp gauge. But I need to repeat the test after a longer drive cycle. Early indications are that the bias is nearly 100% front at light braking, but closer to correct under heavy braking.
Hey - this could be entirely OK for this vehicle, but I still have to verify. I have a slight pull to the right, but that is tiny compared to this major imbalance.
It still remains that after my 40 minute drive home, the rears are lukewarm (110 ish), and the fronts 450+. When I get possession of an IR guage again I can confirm all of this.
So, verify.
Those sound like numbers to be expected.
The ball is in your court.
Jim Johnson
98 SVT
03 Escape Limited
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Originally posted by Big Jim:
I havenot had internet access for the last few days so forgive me if I missed something on this thread when I tried to catch up.
Last I remember someone posted some temp readings from his car then 99fordsvt found an infared thermometer and found similar readings.
Did something else happen, or is 99fordsvt falling back to his original premise?
No, Jim, you haven't missed anything. This guy has yet to grow enough brain cells to figure out he needs to do some maintenance on the FRONT BRAKES. Somebody, please, stick a fork in this thread before any of us stick a fork in our own eyes.
Pacific Green '96 Contour LX V6
â??98 GTP, light mods, 14.66/94
Calypso Green '92 Mustang LX coupe, 13.56/101
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OK MFE,
Ignoring the brain cell comment for the moment, why do you believe the problem is the fronts?
I have my theories why it probably isn't, but I'd like to hear your rational.
And one precursor - the pull to the right, as stated before is only very slight.
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"Absolut Rara."
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Originally posted by 99fordsvt:
OK MFE,
Ignoring the brain cell comment for the moment, why do you believe the problem is the fronts?
I have my theories why it probably isn't, but I'd like to hear your rational.
And one precursor - the pull to the right, as stated before is only very slight.
He's only talking about the pull. I don't believe you have a bias problem at all. Low speed braking simply won't heat up the rear brake rotors much on a contour. This is why the rotors are smaller, because they don't need to be as big to absorb as much heat. Go out and do some max effort stops, and if you can't pass FMVSS135 requirements, then you have something wrong.
Edit - correction due to some of my mustang and future vehicle biases
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Originally posted by 99fordsvt:
OK MFE,
Ignoring the brain cell comment for the moment, why do you believe the problem is the fronts?
I have my theories why it probably isn't, but I'd like to hear your rational.
And one precursor - the pull to the right, as stated before is only very slight.
You clearly DO have your theories about why it isn't the fronts, and it's blinding you to the obvious. You swapped out rear components and now you want to change the whole nature of the braking system all because you don't think there could be a problem with the front brakes, which you haven't yet touched, and which would be responsible for any pull you're experiencing, and despite all the expert testimony that says your theories about the rear are misguided at best. I mean come ON already.
Or...don't. Like I said, you can lead a horse to water, but after a while you just have to let the stupid thing either die of thirst or figure out for itself that it should take a drink. And I, for one, am done.
Bob Marley may have said it best. "In the abundance of water, the fool is thirsty".
Pacific Green '96 Contour LX V6
â??98 GTP, light mods, 14.66/94
Calypso Green '92 Mustang LX coupe, 13.56/101
Crown Autocross Club 1999 Street Tire Champion, 2000/2001/2002 Street Modified Champion
KCR SCCA 2002 Solo II Street Modified Champion
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Nice Marley quotes and horse and water analogies, but WHAT do you THINK is the ACTUAL problem with the front brakes?
I.E. "I think air in the fronts is expanding and causing brake drag" or "Your sliding pins are not free"
You know ..... actual tips or theories not just a bunch of arm waving, insults and sayings. BTW - I disagree with the above but they were just examples.
It sure seems odd that a front brake would apply more force (leading to heat) than commanded. There is not excessive wheel drag in my case.
So I'll repeat, WHAT do you THINK is the ACTUAL problem with the front brakes?
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What, you're so smart you can afford to hold your hands over your ears and shout "la la la la la" to brake experts but you can't fathom what to look for in the front brakes? You're killing me. I told you, I'm done. I'm not going to waste the motion of one more finger to help you out only to be told you don't think any of it could possibly be a factor while demonstrating less than zero willingness to get out and actually do something about it.
Put a proportioning valve in each of your front brake lines and dial it all the way out.
Pacific Green '96 Contour LX V6
â??98 GTP, light mods, 14.66/94
Calypso Green '92 Mustang LX coupe, 13.56/101
Crown Autocross Club 1999 Street Tire Champion, 2000/2001/2002 Street Modified Champion
KCR SCCA 2002 Solo II Street Modified Champion
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I would like to know what would lead you to believe that the front brakes are "applying more force.. leading to heat.. than commanded.
Are you using your IR temp readings to justify this, or simply a theory, or what?
My point is this: You are saying that they are creating "too much heat", and that the rears don't seem to be exhibiting "enough heat" (to paraphrase), and in turn is turning you towards a biasing problem...
With no data to actually prove that is the problem, and only guesses as to the fact that it is, indeed, "too much" heat in the front.. that is as far as you can go, really. Until you can repeat the exact test, on another car identical to yours, you are stuck.. (that or get pressure readings from the lines, and see if you ARE out of range...)
Until then, all I have seen is:
a GUESS that bias is wrong.
some arguments that it isn't.
a few temp readings by me and you..
some guesses that those MIGHT be too high.
key words in there are "GUESS" and "GUESSES". You keep telling people that they could be wrong, etc, etc... (and they could...) but this applies in both directions... theories are only starting points. Data is a foundation that supports your theory. Theories cannot support data, no matter what the data "might" be. So far, nobody in this thread has any "data", at least not in the form of pressure ranges, heat ranges, etc... (RARA and TCE have provided invaluable knowledge on the workings of the braking system, and you and I provided temps.. but this doesn't prove anything.. only disproves (possibly) a problem..)
Let's get to PROVING this problem, or at least get on the track of finding out HOW to eliminate this as a culprit for sure (instead of arguing on why it could/couldn't be... let's just do it...)
Ray
'99 CSVT - Silver #222/276
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Ray,
Thanks for the welcomed civility. I'll track down the IR temp gauge again ASAP -and you are right that it is time to just get more data. Damn day job and paying bills in the way.
The "applying more force than commanded" in the fronts wasn't my theory, it was only in response to MFE's "hey dumbass it is the FRONT idiot .... the FRONT" type of notes.
If the rear bias is too low, but know-it-all MFE says it is the fronts that are the problem not the backs, then the fronts simply get "too much" pressure. I find that hard to buy but was just trying to hear his theories on it - they seem to involve Bob Marley and nothing of substance.
So I am hesitant to disassemble the fronts or change anything yet until I got the existing temps after a longer drive. Then I'll inspect, diagnose and remeasure. Otherwise I can't prove squat of an improvement.
Rephrase for MFE: I don't want to tear apart and alter the fronts until I get baseline data .....(plus I don't believe the problem lies there but amy eventually have to look there).
Funny how getting a good baseline is part of problem solving .... maybe mentioned as part of the CDW27 DVP&R process, huh?
Until I get my data: Can any CEG'er comfortably touch est 110 F your rear rotors immediately after 30-40 minutes of stop/go normal city driving at up to 55 mph?
Flat palm those babies in the rear for 5 minutes and tell me what happens. The brake experts say it is normal to be that cool. I'll glady show you many other front wheel drive vehicles that will nicely roast some skin on the rear rotors after the same driving cycle. Physics identified by TCE and RARA must not apply to those vehicles.
Yes - many ideas and limited data on certain sides, but tons of "idiot .... rears are supposed to be underbiased"
before ANY data is out"
At least they should have flat palmed their rear rotors before palming their keyboard with the expert answer.
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Joined: Jul 2001
Posts: 7,100
Addicted CEG\'er
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Addicted CEG\'er
Joined: Jul 2001
Posts: 7,100 |
There was, if even for a brief moment, a sense of civil conversation to be started. I sense that you still reverted back to word lashing at a few people (RARA, TCE, and MFE) and I am sure its because of your confrontations with them in the past. Let's let "old dogs lie", on both sides, shall we?
So those guys don't wanna listen to you, and you don't wanna listen to them... IF we can't be CIVIL about it, regardless of our disagreement, then we are no better than any OTHER board out there (and I, as well as many, many others rate this board as MUCH better and more mature than nearly any other)
So... deep breaths, all of us..
Ray
'99 CSVT - Silver #222/276
In a constant state of blow-off euphoria.
Originally posted by Kremitthefrog:
I like to wear dresses and use binoculars to watch grandmas across the street.
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Joined: Nov 2001
Posts: 1,176
CEG'er
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CEG'er
Joined: Nov 2001
Posts: 1,176 |
I guess I will jump in here. From what I have gathered from the article that is attached. Maintaining tire grip to road surface is criticle for effectiving braking to say the least. Generally speaking, additional weight load and I quote
The maximum braking force that a particular tire can generate is theoretically equal to the coefficient of friction of the tire-road interface multiplied by the amount of weight being supported by that corner of the car.
I take this to mean that weight that the tires are supporting has a direct relationship in the ability of a tire to apply maximum braking effort. Since most of the weight of the Contour is on the front end, I would take this to mean that more effective braking is accomplished in the front compared to the back which is very light. Since the backend is very light, increasing rear bias could create a very dangerous situation - since the tires would tend to lock-up more and you would lose control due to the light back end. Of course one way to compensate for this would be to add more weight to the backend of the car.
In my general observation, it seems that the front end should handle the major load in braking the car due to the weight it is supporting and the fact that the backend is light and would not provide equal braking ability as compared to the fronts.......
Bob
P.S. And I don't even mention the additional weight added to the front from dynamic load shifting........
http://bobt.gotdns.com/brake.htm
Last edited by btrautman; 03/25/05 04:16 AM.
An ounce of prevention provides a pound of cure!
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Joined: Nov 2001
Posts: 1,176
CEG'er
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CEG'er
Joined: Nov 2001
Posts: 1,176 |
Sheesh, I guess I'm not on the mark here. Hate to think my message shut down this thread 
An ounce of prevention provides a pound of cure!
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