Help, ABS and steering wheel going crazy braking hard
08-31-2018, 12:54 AM
#1
Burning Brakes
Thread Starter
Help, ABS and steering wheel going crazy braking hard
Hi,
I just installed Tarett stud kit (major pain to install) with Girodisc front and Ferodo DS11.1 pads (Gt3 sized front, regular rear) on my 991.2.
I must've done something wrong because when I went to bed in the brakes the car drove fine until I braked hard. Slowing down from high speed, pressing pedal at about 90% max, the ABS went nuts and steering wheel went left-right a lot. Anyone familiar with that setup? Anyone know what I may have done wrong?
Thanks
I just installed Tarett stud kit (major pain to install) with Girodisc front and Ferodo DS11.1 pads (Gt3 sized front, regular rear) on my 991.2.
I must've done something wrong because when I went to bed in the brakes the car drove fine until I braked hard. Slowing down from high speed, pressing pedal at about 90% max, the ABS went nuts and steering wheel went left-right a lot. Anyone familiar with that setup? Anyone know what I may have done wrong?
Thanks
08-31-2018, 01:25 AM
#2
I've not done the mods you mentioned, but from what you've described, it sounds to me that one side has a problem, or at least, more of a problem than the other. The combination of the left-right pulsing and the ABS messages show that probably one side is locking up, causing ABS to take over by pulsing the brakes, and the left-right sensation is that only one side is locking up/releasing. You may be able to see the problem with the wheels removed now that the ABS has been cycled hard. There may be visible grip/release pad contact areas on the rotor now which would indicate which side had the (more severe) problem. BTW, I'm only thinking about the front brakes having this issue right now, since you said the feedback is in the steering wheel.
08-31-2018, 01:45 AM
#3
Burning Brakes
Thread Starter
Thanks, makes sense. Looking at the discs they look the same on both sides right now. Very slight friction marks. I'm wondering since there's more pad surface to the disc if perhaps the ABS goes nuts because brake bias is different? Still the steering wheel going nuts doesn't make sense...
08-31-2018, 09:48 AM
#4
Burning Brakes
Thread Starter
Went back out again this morning, normal driving the car is fine. If I jump on the brakes though the ABS kick in hard, almost pulling ice mode. When threshold braking the front ABS kick on and off.
08-31-2018, 05:22 PM
#6
I don't think I can provide much help just by memory of the brake set up. However, IMO, from your drive this morning, it seems like ABS might be working fine, but maybe the threshold has changed at where ABS kicks in...? Were you familiar with the ABS activation threshold before the brake upgrade, or is this the first time you've activated ABS with your current set up (aside from new brakes)? You mentioned that you put in GT3 sized brakes pads on the front, can you put the old pads back in as a test to see if the problem goes away? Also, perhaps your new pads are much grippier than the old ones and therefore would work better with sticky track tires... I'm just throwing out ideas.
08-31-2018, 05:41 PM
#7
Rennlist Member
I'm practically certain that you would get an error code if the wheel wasn't seeing the pulses it uses to monitor the rotation rate of the wheel. I doubt you damaged anything there or you would see errors even during normal driving since the computer would quickly realize it couldn't "see" the wheel turning.
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09-01-2018, 11:41 AM
#8
Burning Brakes
Thread Starter
What's weird is that I apply the same brake pressure and at high speeds the car brakes fine but as speed gets lower ABS kicks in at the same applied pressure. I'm on MPSC2 tires with some life left. No difference whether the tires are cold or hot. Tried with PSM off and no change. Studs were installed without sleeves, wondering if the calipers are moving slighly?
09-02-2018, 02:24 PM
#10
Burning Brakes
Thread Starter
09-03-2018, 09:01 AM
#12
The stud diameter is less than the original caliper bolt diameter. There is a full diameter shoulder at the bottom end of the studs, but this may not be long enough to fully immobilize the caliper. Check with Girodisc but I think you need the sleeves. Adding spacers only affects the needed stud length.
09-04-2018, 10:17 AM
#13
Burning Brakes
Thread Starter
As per Tarett's website:
" Now Available for using our Brake Caliper Stud kit with the GiroDisc brake upgrade. If the GiroDisc caliper spacers are 7mm or more, these adapters can be used to make them compatible with our brake caliper studs. Four adapters are required per axle or stud kit. Stud kits sold separately. No adapters needed for spacers less than 7mm thick. "
So no adapter needed with spacers less than 7mm
" Now Available for using our Brake Caliper Stud kit with the GiroDisc brake upgrade. If the GiroDisc caliper spacers are 7mm or more, these adapters can be used to make them compatible with our brake caliper studs. Four adapters are required per axle or stud kit. Stud kits sold separately. No adapters needed for spacers less than 7mm thick. "
So no adapter needed with spacers less than 7mm
09-04-2018, 12:10 PM
#15
In that case I would pull the calipers off the studs, check everything for proper fitment and retorque. Be sure the calipers are fully seated when retorquing. Good luck and let us know what the solution turns out to be.