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Well, after all the brake balance posts lately, I've been doing a lot of reasearch, thinking, and driving. I've determined that I think the Contour is too front-biased. I know, it's for safety. I don't give a [censored]. I want better stopping, so I'm willing to mess around and test the braking, seeing if I can get the proportioning valve to spit out pressures a little bit closer to the actual weight balance. Is this possible? Is there any simple way to adjust the proportioning valve on this car? Also, I'm not interested in brake upgrades. I'm still not sure if I want to keep my Contour as my primary racecar, so for now the only thing on the horizon is a set of SS hoses and another flush. I can hit the ABS from 100 to 0 a few times before I need to let them cool (and bleed/flush  ), and from 60-70 all day long. My Fuzions and suspension are the weak links in this chain.
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"Absolut Rara."
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"Absolut Rara."
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Moving the brake bias to the rear will only really help if you increase weight on the rear axle.
You state that you don't care about safety, but I don't think you realize what actually happens on an overly rear biased car. Snap oversteer is the order of the day, and the car becomes INCREDIBLY dangerous under braking because of it.
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Joined: Mar 2002
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CEG\'er
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Oh no....
Please; just do whatever you wish and send us the pics afterwards.
Instead of coming asking for answers you don't want to hear anyhow, do what you feel is the solution and post your findings. Don't tell us your problems, offer us your solutions.
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Joined: Aug 2003
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I know how this works, guys. I know "balance is the key", Rara. I was just wondering if there was any little part that could make adjusting bias easy. I'm not going to hack up the proportioning valve, I need it to be reversable. I plan on testing any mods I do carefully, and backing off when I go too far. I know what happens in a car when the rears lock up first. I know I don't want that. I also know that Ford really played it safe with the biasing, and that while 70-80% of the weight is still on the rear tires under hard braking, only 10% or so of braking force is applied there. I want a better match, so that when I threshold brake under worst-case scenarios, I put just a tiny bit less than makes the rear go first. I know how brakes should be set up for racing, I just wanted to know how to get them there.
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Originally posted by 95Sleeper:
I know how this works, guys...... I also know that Ford really played it safe with the biasing, and that while 70-80% of the weight is still on the rear tires under hard braking, only 10% or so of braking force is applied there.
Um, no you don't ACTUALLY.
First off. Weight bias on the Ford Contour is 62/38 - F/R. Under braking this can go up to 75/25. So your inital assumption is flawed. The car shifts weight forward under braking - no denying that. Unless you drive everywhere in reverse. 
Lets please drop this stupid topic that keeps coming up.
If you want better breaking. Get Todd to set yu up with some big front brakes and call it good. Sure you can upgrade the rears while you're at it, but the benefit there is purely aesthetic.
End of story.
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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Joined: Sep 2000
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"Absolut Rara."
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"Absolut Rara."
Joined: Sep 2000
Posts: 3,223 |
Originally posted by 95Sleeper:
I know how this works, guys. I know "balance is the key", Rara. I was just wondering if there was any little part that could make adjusting bias easy. I'm not going to hack up the proportioning valve, I need it to be reversable.
If you REALLY wanted to do it, you would need to gut the stock valve so it is just a pass through, and then install aftermarket adjustable prop valves in the rear lines. One for each side, because this is a diagonal split system.
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I plan on testing any mods I do carefully, and backing off when I go too far.
Um, do you have your own proving grounds I don't know about? How would you go about doing high speed dynamic testing???? let alone safely . . .
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I know what happens in a car when the rears lock up first. I know I don't want that. I also know that Ford really played it safe with the biasing,
If Ford played it as "safe" as you claim, they would have cost reduced out the rear brakes entirely. Ford still has performance targets, both internal, and regulatory to meet. So, rear brakes are biased as much as they safely can be with the factory brake components.
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and that while 70-80% of the weight is still on the rear tires under hard braking, only 10% or so of braking force is applied there.
This is damn near the funniest thing I've ever read. A car w/ a 80% rear weight dist. wouldn't be able to steer around a corner, it would understeer like mad even under mild cornering.
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I want a better match, so that when I threshold brake under worst-case scenarios, I put just a tiny bit less than makes the rear go first. I know how brakes should be set up for racing, I just wanted to know how to get them there.
Get more aggressive pads then. Better performance all around. Are you going to be actually racing your contour? on a track? Do you have high performance driver training? Do you have brake development training to know how to actually tell where you are when modifying the bias?
Probably not on most if not all of those accounts. I'd recommend sticking with street parts, or at the very least stuff available from reputable brake upgrade suppliers.
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Originally posted by Rara:
Originally posted by 95Sleeper:
I know how this works, guys. I know "balance is the key", Rara. I was just wondering if there was any little part that could make adjusting bias easy. I'm not going to hack up the proportioning valve, I need it to be reversable.
If you REALLY wanted to do it, you would need to gut the stock valve so it is just a pass through, and then install aftermarket adjustable prop valves in the rear lines. One for each side, because this is a diagonal split system.
Thanks. That's what I wanted to know. I was afraid that was the only way to do it. I've been poking around for a used prop valve in good enough shape to pull. I might end up getting a new one if this goes wrong. In any case, I want to keep costs down and be able to revert to stock.
Originally posted by Rara:
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I plan on testing any mods I do carefully, and backing off when I go too far.
Um, do you have your own proving grounds I don't know about? How would you go about doing high speed dynamic testing???? let alone safely . . .
A friend of mine owns a restaurant a litte out of town. It has a long paved parking lot that I romp around in to keep sharp. 60 mph stops are no problem. And I can interpolate data for higher speeds, to a certain degree. I won't be messing with the stock knee too much, I don't think.
Originally posted by Rara:
Quote:
I know what happens in a car when the rears lock up first. I know I don't want that. I also know that Ford really played it safe with the biasing,
If Ford played it as "safe" as you claim, they would have cost reduced out the rear brakes entirely. Ford still has performance targets, both internal, and regulatory to meet. So, rear brakes are biased as much as they safely can be with the factory brake components.
I told you, I've done quite a bit of research, and I believe that it is common to see a car with less than optimum biasing. Some Sentras are too rear biased, for some assinine reason. Also, if I do this, my car will not be on stock suspension for long. I'm still debating making the Contour my track car, and holding off on mods for now.
Originally posted by Rara:
Quote:
and that while 70-80% of the weight is still on the rear tires under hard braking, only 10% or so of braking force is applied there.
This is damn near the funniest thing I've ever read. A car w/ a 80% rear weight dist. wouldn't be able to steer around a corner, it would understeer like mad even under mild cornering.
Sorry, typo. I meant 70-80% of the weight is up front under threshold braking.
Originally posted by Rara:
Quote:
I want a better match, so that when I threshold brake under worst-case scenarios, I put just a tiny bit less than makes the rear go first. I know how brakes should be set up for racing, I just wanted to know how to get them there.
Get more aggressive pads then. Better performance all around. Are you going to be actually racing your contour? on a track? Do you have high performance driver training? Do you have brake development training to know how to actually tell where you are when modifying the bias?
Probably not on most if not all of those accounts. I'd recommend sticking with street parts, or at the very least stuff available from reputable brake upgrade suppliers.
I'm running bendix right now. I will go with a track pad when and if this becomes a track car. And yes, I Solo 2 as much as possible now, and am looking to get into Solo 1 this summer. I just haven't decided on a car. I keep going back and forth between the contour and a miata. I know the Miata is a better race car, but I want to prove how fast a Contour can be. And I won't be on the track much, it's all auto-x and hillclimbs around here. But hillclimbs are close to the track. I have taken an auto-x focused school, and am taking a full-blown school as soon as I pick a car and get it track-ready. I am an engineer, and understand braking systems very well. I have a friend who tracks his 94 and 03 Cobras and will help with the setup. Rara, you are one of the few people I fully respect here, please realize I'm not a stupid punk kid who just pulled an idea out of his ass. I wanted to get your take on this now since this will all happen over the summer when I will be on dial-up, when I have a comp at all, and so I'm doing research now. Do you really think there is no more braking to be had by doing this?
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Originally posted by Stazi:
First off. Weight bias on the Ford Contour is 62/38 - F/R. Under braking this can go up to 75/25.
On a good day or a modified car.
I know you are just proving a point but to throw some digital scale numbers out. They would actually make your statements be a best case scenario and add more credence to what you are saying.
{FYI}
Actual weight balance is worse then that. It's more like 64/36 or a bit worse.
With very strategic front end lightening it can come down to 61.5/38.5 with the driver in the car.
However as the fuel cell empties the balance again moves forward lifting weight off the rear wheels. Thus pushing it back towards 63/37.
You may not think that small change means much but look at it this way. Just 2% is a +60 / -60 lb weight shift.
The best weight balance I could get was a full tank of full and an Optima in the rear right corner of the trunk. With driver it was 60.4/39.6
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Sep 2000
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"Absolut Rara."
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"Absolut Rara."
Joined: Sep 2000
Posts: 3,223 |
Personally, I think you are straining at a gnat here. IF you gain anything, it will be minimal, and require a lot of work to get there, and you still won't be quite sure.
If you want to shift the bias to the rear a little, you can put more aggressive pads in the rear and not the front. But, since you are looking for improved performance, I still say just go with more aggressive pads all the way around, or upgrade the size of the system overall, either w/ the CSVT or FSVT brakes or bigger, like Todd TCE's Wilwood kits, etc.
It's almost like spending $750 to redesign an intake manifold to make more power, when a $1000 supercharger is legal to run and makes way more power. Further, bias is a dynamic thing, the necessary proportioning is constantly changing due to vehicle loading, cornering loads, road grade, pad types, road surface conditions; and a ton of other things. OEM's spend months and months of time and hundreds of thousands of dollars determining how to set up valving on a new brake system to cover everything. You will never hit all the conditions, and when you run into one you missed, and you snap oversteer into a tree . . . its a bad thing. Leave the proportioning alone until its a fully gutted and caged track only car; OR you have dramatically changed the brake system, and the new parts weren't designed to work w/ the stock valving.
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I'll take a quick stab at the % and say that the hard braking numbers are far worse than you suggest. If it's 65/35 now I'll bet you it's more like 85/15 under hard braking.
Get some data like wheel base, Cg and corner weights, toss out a g load and a couple of us can spit out the numbers from a spread sheet.
Haven't used this in a looong time so bear with me... try this:
Longitudinal Weight Transfer
Weight 3200 lbs.
Rear % 35 %
CG Height 22 in.
Acceleration 1.2 g
Wheelbase 106 in.
Transfer 797.0 lbs. total
Front Weight 1438.5 lbs./wheel
Rear Weight 161.5 lbs./wheel
* Hmm, that's 89/11 assuming my numbers are even close. Lucky guess?
Last edited by Todd TCE; 04/28/05 12:24 AM.
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