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Old 11-22-2005, 01:59 AM   #1
Fred
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Default Rallycross braking problem

Rallycrossed the STi 11/20/05 at Oakland Acres, VA. Only had RE070's and Falken RT615's to choose from, so I used the RE070's. Stock wheels. Had a braking issue. Description & conjecture follows...

Coming out of wet or tight (meaning lots of sideways wheelspin) corners, I would accelerate through the next "straight" then hit the brake pedal & it would go waaayyyy down & barely slow the car. Hit it again & braking is back to normal. Some braking zones actually required hitting the brake pedal 3X to achieve completely normal operation.

Never occurred anywhere but on course. Hitting the brakes after just driving around on the bumpy terrain off the course would result in normal braking. The rallycross in NC on 11/19/05 didn't affect the car in this way, either. Haven't had the problem in the 300+ miles since leaving OA.

I'm thinking that maybe as I came out of the corners & blended up the dirt (very fine clay dust), it would coat the rotors. Then when I hit the brakes, the dirt would be between the pad & rotor, causing the loss of braking. But why would the pedal travel down that far if that were the case?

Stock STi brakes with ABS disabled and Carbotech Bobcats replacing all OE pads.

If you know what was going on, please let me know - and tell me what to do to fix it.
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Old 11-22-2005, 02:04 AM   #2
Midnight_Gold
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Sounds like the stereotypical '04 hub issues.. weeble wobble pushes the pads back after hard turning causing the first pump to simply push the pads back into normal operating position. You should probably start doing confidence taps before you need to brake hard.

Orrrr.... you could purchase a Trackmonkey Racing hub conversion kit to totally fix the problem.

~ Miranda
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Old 11-22-2005, 02:32 AM   #3
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or you could get some floating rotors and see if that helps counter any of the deflection in the front hub, lessenging the pad knock back
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Old 11-22-2005, 04:40 AM   #4
silentbob343
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or swap to the 05 Hubs, there is a 04 to 05 hub conversion thread on here somewhere.
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Old 11-22-2005, 11:41 AM   #5
Storm
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Why not try disconnecting the ABS before you totally rebuild your hub assemblies? Rallicross is not "normal" driving...your braking is not going to be "normal" until you're moving slow enough for the absolutely-non-rally-oriented tires to work.

Just a thought anyway.....
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Old 11-22-2005, 01:59 PM   #6
Fred
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Quote:
Why not try disconnecting the ABS before you totally rebuild your hub assemblies? Rallicross is not "normal" driving...your braking is not going to be "normal" until you're moving slow enough for the absolutely-non-rally-oriented tires to work.


translation: I didn't read your whole post, but I figure you're probably a NOOB, so I'll treat you like a dumbass.


Last edited by Fred; 11-22-2005 at 02:05 PM.
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Old 11-22-2005, 02:04 PM   #7
Fred
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Quote:
weeble wobble pushes the pads back after hard turning causing the first pump to simply push the pads back into normal operating position. You should probably start doing confidence taps before you need to brake hard.
I've had this problem ONLY at Oakland Acres. Braking was normal at our rallycross on Saturday (even though there was a lot of wheelspin there too), and hard driving anywhere non-rallycross related (even on bumpy pavement) results in normal braking, abs enabled or disabled. Braking at OA was only affected after coming out of particularly loose corners, where I was spinning the wheels a lot. Coming out of corners where there wasn't as much wheelspin (more grip, more of a "patience" corner, etc.), the brakes would be normal when I hit them the first time.

Still think it's weeble wobble?
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Old 11-22-2005, 03:39 PM   #8
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Quote:
Originally Posted by Fred
I've had this problem ONLY at Oakland Acres. Braking was normal at our rallycross on Saturday (even though there was a lot of wheelspin there too), and hard driving anywhere non-rallycross related (even on bumpy pavement) results in normal braking, abs enabled or disabled. Braking at OA was only affected after coming out of particularly loose corners, where I was spinning the wheels a lot. Coming out of corners where there wasn't as much wheelspin (more grip, more of a "patience" corner, etc.), the brakes would be normal when I hit them the first time.

Still think it's weeble wobble?
I do - mostly because what else could cause that? If the brakes go away -then come back with a tap then SOMETHING is pushing the pistons back - what else could it be?
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Old 11-22-2005, 04:48 PM   #9
MoDrift
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Fred - I've had the exact same experience at RallyCrosses, and it probably happens 2 out of 4 runs. 2004 STi, stock everything, ABS enabled.

It never happens on course, but after the run, I start the drive back over the grid, and when I apply the brakes at that time the pedal goes to the floor and the car doesn't stop. The ABS isn't engaging, the pedal just goes to the floor like I've lost fluid pressure. I've just learned to pump the breaks when I come into grid since it happens so often. Has never happened outside of RallyCross, even with playing in rough terrain elsewhere.

I was thinking it was my brake fluid since RallyCross tends to shorten the life of fluids in general. Recently changed it, but haven't run since then to see if there is a difference.
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Old 02-27-2006, 09:42 AM   #10
Fred
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Ok, so it is pad knockback from weeble wobble - had an autox test & tune this weekend, and got the same pedal problem at every braking zone. Guess I'll be looking into the hub conversion and other possible cures...
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