Chris Edwards

Hey all, a little background first. I bought a bone stock 01Z in great with 67k back in February from a little old lady. I installed Pfadt JOC shocks, JOC sways, solid endlinks, along with a Hardbar cam lock kit, and T1 front control arms. I had to replace the rear outer tie rod ends since they had a bit of play in them. I lowered the car about 1/2" on stock bolts, set toe to 0 front and rear, and put 3,000 trouble free miles on the car. Having put sufficient street miles on the car to prove its reliability, I decide to get ready for a track day. In preparing for the track, I install Goodridge braided lines, and bleed the system with Castrol DOT4 fluid using my Motive power bleeder, and I install new XP12/ XP10 pads onto my stock rotors. I bed them per Carbotech's instructions and I can smell them at the end of the bedding session. At this point, I notice that the ABS engages extremely easily. To a point that I don't think is normal. The stock pads felt 'normal' but obviously I never went to the track with them so I don't consider them to be an accurate point of comparison.

Since I never had a chance to corner weigh the car, I do that and then I have my local chassis/ alignment shop align the car per Pfadt's guidelines. The alignment guy said there was a tad bit of rear thrust, so I think to myself, hmmm maybe that's why the ABS is kicking on so soon?

The spec's came in at:

Front Camber:
-1.9* / -1.9*

Front Caster:
-6.1* / -6.2*

Rear Camber:
-1.5* / -1.5*

Toe:
Front: -1/16"
Rear: -1/8"

Doesn't look like there's enough front caster no?

Firstly the car drives beautifully and feels very flat and neutral. Scaling the car and adjusting the endlinks so they don't have any preload made an incredible difference.

But the ABS still kicks on FAR too early. I can feel the front right pulsing a bit more than the rest, I think. I decided to reinstall the stock pads just for comparison's sake (I read that Carbotech's can easily overpower street tires), and they don't engage ABS quite as quickly as the Carbotech's, but they do engage the ABS too early for what feels like normal. The stock pads (I assume they were replaced) have ~3/4 pad life left, rotors look great.

The tires are still my street tires... 315/35/17 Sumitomo HRZ front, 335/35/17 Michelin Pilot Sport rear. Both front and rear tires are quite fresh and have great tread, car is silky smooth past 120mph.

I had an open track fox body Mustang that I built previously with full Maximum Motorsports suspension (tubular k-member, coilovers, torque arm, panhard bar, etc), 3100lb car without me (the Z weighs 3130 with a half tank without me). For the Mustang, I used OEM 94-04 Cobra brakes and Hawk black pads (13" front rotors, PBR dual piston calipers, and 11.65" rear rotors with single piston calipers), I could stand on the brakes from 140mph and they would not lock up... on fresh NT05 tires. Even on OEM Cobra pads, the brakes worked amazingly.

Anyone have any idea? Possibly a bad Goodridge line? Stuck caliper? Air in the ABS system? Malfunctioning ABS module? I have no codes besides those for the o2 sensors from the LG header install...

sleeperstyle

if there are no codes... don't know but my abs is super touchy also with both of my c5's. if there is any lockup detected it will go off.

not to be a d#ck but are you sure your technique is correct?

and i figured out that i had too much rear pad, hence setting the abs off before the front reached its threshold- when i LOST my abs at a track weekend- started locking up the rear tires.

good luck

lefrog

Your problem might be right there. With different tire compounds they are likely to reach their limit at different times, the one that reaches its limit first will lock and trigger the ABS.
I never drove the Sumimoto but I heard pretty bad reviews about them and I wouldn't be surprised if the Michelin have much higher grip levels.

If you had a faulty ABS sensor that would trigger a code I think, so I would investigate the tire setup before anything else. Also, what traction control mode are you using?

Adam@Amp'dAutosport.com

plus you have to much pad for a street tire. You should be on 10 & 8.

froggy47

Technique & tire mismatch mainly, then everything else. ABS is calibrated by GM for the GM stock EVERYTHING setup. ABS does not "adjust itself" every time you add/change a part on the car. You start changing things it'll engage differently.

All you can do to get it back where you want it is pad compound, tires, alignment, technique. Mostly in that order although it could be the tires mainly.

Chris Edwards

I know something is not right... even on OEM junkyard pads, OEM 13" rotors that were pulled out of the backyard, and dry rotted tires mismatched street tires (pre-NT05), my 4-wheel disc non-ABS fox body stopped better than the Vette. Something can't be right.

I've never owned an ABS car, so I'm not sure if this is normal, but when using the Motive power bleeder to bleed the brakes (pumped it to 15psi), when I cracked the bleeder screws I only got a trickle coming out of the line... on my fox body I would get a stream, seemed much more volume was coming out than with the Vette. Is it possible that all 4 of my Goodridge lines are kinked? I have to admit, I've had this thing apart so many damn times, there was once or twice where the calipers might have yanked on the lines a bit...

lefrog

Do you still have the rubber brake lines?
Did you ever get air in the system that could have never been flushed out from the ABS?
There are good threads on the forum that discuss bleeding the brake system.

racer313g

This. Too much brake and not enough tire. If you want to run on street tires you need to go to the 10/8 combo. Even then you can get into the abs very easy on the track.

Chris Edwards

I have Goodridge braided lines. I'm beginning to wondering if they aren't kinked though?

I'm really not sure if there's air in the system that wasn't flushed out. I bled and bled and bled and there's not a single bubble of air visible in my clear hose from any of the calipers.

What volume of fluid is normal when bleeding? Is a trickle normal or should it be a steady strong stream?

racer313g: I reinstalled my stock pads for the time being...

froggy47

Drip/trickle with my Motive 12 psi = normal.

sleeperstyle

If you don't like the abs- and have experience without it, disconnecting a wheel sensor will disable all tcs/ abs and make the car like your old mustang= no nannies. Do at your own risk. Flat spotted tires suck, but if you threshold brake and the thing stops like a champ and no locking up then you know you have a problem with the abs.

mikeCsix

Air in the brake lines will give your pedal a mushy feeling / soft pedal. I think our problem is too much brake pad and mismatched tires. I would replace the fronts to match the rears and would go with carbotech 10's and 8's. Even that may be a bit much for street tires but I defer to Adam at CarboTech on that. Better yet, give Adam a call. His customer support is awesome.

RMDZidane

I have the XP10 XP8 combo on my car with MPSS and I agree that it is maybe a touch too much for my tires during hot track days. I activate ABS more as day progresses but the pads are still fantastic for dual use

rustyguns

way too much pad and for street tires, stock Z06 pads are plenty!

and you must match the tires! those compounds are completely different!