would too much rear break bias cause a spin under HARD braking?
05-18-2013, 09:24 PM
#1
Drifting
Thread Starter
would too much rear break bias cause a spin under HARD braking?
hi - i was at the glen today. Running pretty hard on the front straight, as I braked for turn one, still going straight, then rear jumped to the left slightly, I made a tiny correction, and then it jumped hard back to the right and kept going right around and I did a full 360.
corded four hoosiers. Was coming off a 2:05.5 lap.
scary as ****. Inches from the wall.
My friend with a fast z06 says he had similar issues with more aggressive pads and now he runs stock calipers with crappy street rear pads (AP T1 kit up front).
I have wilwood slr6 up front with dtc70 and wilwood slr4 in the rear with a wilwood race pad (H compound).
if this is an issue with brake bias caused by the rear race pad, why didn't it rear its head earlier in the day or a few weeks back at NJMP?
or should I be looking for something else?
no TC was used. I still run with stock ABS. 275 A6's.
corded four hoosiers. Was coming off a 2:05.5 lap.
scary as ****. Inches from the wall.
My friend with a fast z06 says he had similar issues with more aggressive pads and now he runs stock calipers with crappy street rear pads (AP T1 kit up front).
I have wilwood slr6 up front with dtc70 and wilwood slr4 in the rear with a wilwood race pad (H compound).
if this is an issue with brake bias caused by the rear race pad, why didn't it rear its head earlier in the day or a few weeks back at NJMP?
or should I be looking for something else?
no TC was used. I still run with stock ABS. 275 A6's.
05-18-2013, 09:54 PM
#3
Safety Car
also going into turn one is down hill which shifts weight off the rear tires 
so it is also a driver issue up hill would do the opposite.... your into fine tuning for different track here 
05-18-2013, 10:59 PM
#5
Tech Contributor
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I had the same problem last year when running Wilwood H compound in the front and Raybestos ST47 in the rear. When I talked to the guys at Porterfield I was told the 47 is more aggressive than the H and the compounds should have been swapped between axles. Not sure where the H stands against the DTC70 but the guys at Porterfield might be able to help you.
Bill
Bill
05-19-2013, 12:06 AM
#6
Burning Brakes
I run DTC 70's on all 4 corners. Anytime I brake going down hill hard you better have the car settled and in a straight line or your gonna need some fast hands and brake modulation.
05-19-2013, 10:17 AM
#8
Safety Car
Scott - since you have a pre-'01 car, you do not have active brake bias proportioning like the C5Z did. So your brake bias is now a bit more important.
If you get around to it, measure and post the front and rear piston sizes and then we can match the rear pads to get back to the desired F/R bias.
T1 at Lightning has a bump in the braking zone, which apparently did not upset your car -- BUT the big difference btw T1 @ WGI and T1 @ Lightning is that the braking zone for the 90 is downhill, so the rear gets really unloaded under braking and the braking zone is bumpy, so if your bias is off, it is more likely to cause problems.
I think you can fix the issue w/o ditching your rear setup - I think those pad sizes are pretty common so ones with the correct mu will be available.
If you get around to it, measure and post the front and rear piston sizes and then we can match the rear pads to get back to the desired F/R bias.
T1 at Lightning has a bump in the braking zone, which apparently did not upset your car -- BUT the big difference btw T1 @ WGI and T1 @ Lightning is that the braking zone for the 90 is downhill, so the rear gets really unloaded under braking and the braking zone is bumpy, so if your bias is off, it is more likely to cause problems.
I think you can fix the issue w/o ditching your rear setup - I think those pad sizes are pretty common so ones with the correct mu will be available.
05-19-2013, 11:52 AM
#9
Drifting
Thread Starter
On phone at track but quick update. Cleared codes on computer. First lap "service abs/ traction control". Codes:
C1226 h - rf excessive wheel speed variation
C1333 h - rf wheel speed circuit open or shorted
So friend at track had ac delco hub and waiting to go out again
C1226 h - rf excessive wheel speed variation
C1333 h - rf wheel speed circuit open or shorted
So friend at track had ac delco hub and waiting to go out again
05-19-2013, 01:14 PM
#10
Drifting
Thread Starter
Crap. Same codes came back on with new right front hub.
05-19-2013, 01:58 PM
#12
Safety Car
Bypass the connector coming from the chassis harness (which probably means soldering the hub wires to the harness wires).
I had the same thing happento me, on the RF. I replaced the troublesome OEM connector with a weatherpack and have been good since.
I had the same thing happento me, on the RF. I replaced the troublesome OEM connector with a weatherpack and have been good since.
05-19-2013, 02:42 PM
#13
Drifting
Thread Starter
2 wires melted together under exhaust manifold. I think i fixed it. Waiting for last session....
05-19-2013, 11:11 PM
#14
Drifting
Thread Starter
finally got one session in. long day!
is that ABS wire/speed sensor wire supposed to run near the exhaust manifold? or was that done by a previous owner? anyway, I fixed the wire and routed it away.
set a new personal best for myself at the Glen of 2:03.2:
is that ABS wire/speed sensor wire supposed to run near the exhaust manifold? or was that done by a previous owner? anyway, I fixed the wire and routed it away.
set a new personal best for myself at the Glen of 2:03.2:
05-19-2013, 11:12 PM
#15
Drifting
Thread Starter
and here is the spin from 2 view points
05-20-2013, 12:12 AM
#16
Melting Slicks
I had the same problem last year when running Wilwood H compound in the front and Raybestos ST47 in the rear. When I talked to the guys at Porterfield I was told the 47 is more aggressive than the H and the compounds should have been swapped between axles. Not sure where the H stands against the DTC70 but the guys at Porterfield might be able to help you.
Bill
Bill
05-20-2013, 09:51 AM
#18
Supporting Vendor
Member Since: Oct 2002
Location: Cleveland OH
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St. Jude Donor '11,'13
You might want to try the Carbotech XP20 front with XP10 rear, this will help your bias.
__________________
Adam Adelstein
Amp’D Autosport.com
Internet's largest retailer of Carbotech Performance Brake Pads.
PH:216-780-8825.
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All major CC and Pay Pal accepted.
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Adam Adelstein
Amp’D Autosport.com
Internet's largest retailer of Carbotech Performance Brake Pads.
PH:216-780-8825.
Email: sales@ampdautosport.com
Web Site & Direct ordering http://ampdautosport.com/
All major CC and Pay Pal accepted.
Check out Promo code:z28
05-20-2013, 12:31 PM
#19
Drifting
Thread Starter
05-20-2013, 10:35 PM
#20
Le Mans Master
