Barbara_S

Hi, I used performance friction Z rated pads on my C4 for the last couple of years autocrossing. They worked well , were reliable for hard stopping, and seemed like good pads for street use too. A few times, too much left foot braking got me to lose them altogether at the end of the run, sort of a surprise having no brakes when getting ready for the next run. I used Motul fluid , so I'm not sure if this problem could be helped with different rotors, maybe slotted rotors might help cool the brakes more?? or maybe I just need to do a better job with the brake and throttle. Anyway....

My new ZR1 needs rotors and brake pads so this is my chance to upgrade if there's a clear better choice/setup.

Any opininions from the C4 guys?

thanks,

STEVEN13

Hi,

While I don't do any auto-x's. I do run at Pocono and Limerock (time trial events) and I use PFC 01s (front) and 97s (rear). Also use Motul. I have the GS calipers and SS brake lines and front cooling ducts.

Never have any problems even when I ran the smaller front brakes. On the street these pads are loud and very dusty. They do stop good even when cold.

Steven

larryfs

sounds like you boiled your fluid.
can't imagine how you did that at auto-x, but I guess it's possible.

BrianCunningham

Check your lines, if they are old, they could be getting ready to rupture.

Also was the ABS unit bleed correctly?
Is there a leak from the master cylinder?

check the whole system out.

I've seen Vette boil their fluid at an autocross, but that was usually with the 12in brakes, not your 13's

Did you completely change the fluid or just top it off?

Barbara_S

I was stunned at the feel of no brakes when the fluid boiled last year so I switched to Motul. That's also when I started controling turning with the brake while not letting up much on the throttle - it seems to work well, and the end of our typical courses tend to have a lot of turns to slow everyone down. I did have a reliable shop change the fluid - I'll have the system checked - thanks.

c4cruiser

From your description of "controlling turning with the brakes" sounds like you are simply riding the brakes and building up excessive heat. In addition to slowing the car, you are keeping power on with the brakes applied and that makes the brakes work even harder than simply braking to slow the car.

Try braking hard as you get to a turn and let off completely as soon as you feel you have the speed lowered enough to enter the turn without the car sliding and then apply power at or just after the apex to exit and complete the turn. Your rotors will like it and you may wind up going faster.

As far as rotors, I woud just go with a stock replacement rotor and not bother with drilled/slotted versions. You will save a lot of money that you can spend on good pads. For my 87 with the small 11.5" rotors, I buy the cheap "white box" rotors and toss them after a season. I use Hawk HP+ pads and they can eat up the generic rotors but they are great pads for both autocross and some track use.

I spend about $25 each for the front rotors and $22 for the rears. I also use them for some track days and if they get eaten up after an event, I still don't spend a lot of money.

Depending on the speeds you see on your autocross courses, you may want to try cooling ducts and point them at the caliper. You may not build up enouh speed to make it worthwhile but it will help some.

Bill Dearborn

I autocrossed my 86 for 6 years and never had a problem using OEM pads and DOT3 old brake fluid. You should not get the brakes hot enough to boil the fluid when autocrossing unless you are doing something wrong. When I first ran my 86 I used OEM pads with the small rotors and never had a brake problem in an autocross. After a couple of years I updated to the larger Z51 brakes and still used OEM pads without any brake problems. I never bothered to bleed the brake fluid since it didn't get hot enough to boil even with water soaked DOT 3 fluid. The only brake problems the 86 had were at high speed tracks like Watkins Glen where the stock small rotored brake system would exhibit pad fade after 3 laps. Once I went to the big brakes I stopped having that problem.

Bill