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Joined: Mar 2003
Posts: 7,117
Hard-core CEG'er
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Hard-core CEG'er
Joined: Mar 2003
Posts: 7,117 |
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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Joined: Feb 2003
Posts: 117
CEG\'er
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OP
CEG\'er
Joined: Feb 2003
Posts: 117 |
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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Joined: Jul 2001
Posts: 7,100
Addicted CEG\'er
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Addicted CEG\'er
Joined: Jul 2001
Posts: 7,100 |
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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Joined: Apr 2003
Posts: 3,045
Hard-core CEG\'er
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Hard-core CEG\'er
Joined: Apr 2003
Posts: 3,045 |
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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Joined: Feb 2003
Posts: 117
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CEG\'er
Joined: Feb 2003
Posts: 117 |
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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Joined: Sep 2000
Posts: 3,223
"Absolut Rara."
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"Absolut Rara."
Joined: Sep 2000
Posts: 3,223 |
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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Joined: Apr 2001
Posts: 383
CEG\'er
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CEG\'er
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Posts: 383 |
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
KCR SCCA 2002 Solo II Street Modified Champion
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Joined: Sep 2000
Posts: 3,223
"Absolut Rara."
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"Absolut Rara."
Joined: Sep 2000
Posts: 3,223 |
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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Joined: Feb 2003
Posts: 117
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Joined: Feb 2003
Posts: 117 |
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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Joined: Oct 2000
Posts: 4,149
Hard-core CEG'er
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Hard-core CEG'er
Joined: Oct 2000
Posts: 4,149 |
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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