This last race weekend I debuted my "new" car. The car has performance friction 97 pads currently installed. At this event I experienced major lockup in my front left wheel. In my previous car I had the hawk dtc 70/60 combo and loved it, I felt that those had plenty of modulation and were easy to determine where the edge was. This last weekend I didn't experience any of that, I had no feedback in the pedal and I felt that the range from threshold to lockup was very minimal and very difficult to get "just right." Every time I didn't lockup I was outbraked, which was very frustrating as deep braking is/was one of my favorite passing techniques. I was running RA-1s with a birth date of 2006 that probably have well over 30 heat cycles, in other words they were ran from full tread and are now complete slicks or close to it (barely 2 lines) even though they were old I was still able to put down competitive laps with them. I corded and blew the front left tire in one session then corded another tire on the front left again in the next because of the crazy lockup. Killing 2 tires in 1 day is not my idea of low cost racing.


The pads are nearly new, I inspected the rotors and they did have some decent grooves.

My questions are, has anyone else ran performance friction pads and what are your opinions of them, can a warped rotor cause this kind of severe lockup, bad pads, improperly bled lines, bad caliper, tires too old, bad driver? I want to fix the problem before the next race, I dont have any more tires to ruin, can't afford anymore at 170+ each and ,even if I could, RA-1's are currently on back order nationwide (again).
So far I've ordered a new set of rotors and plan on re-bleeding the system, I inspected the front calipers and they look, well, like calipers... I have a set of EBC yellow pads as possible backup, anybody use those? I've heard that they may be too weak for competition.

I think you need a unbalanced set like the 70/60 combo ... and once you had any flat spot the tire will stop turning at that place . it's all good !

I ran Hawk blues in my Spec Miata after trying 5 or 6 other brands and came back to them. I just ran my 944 for the first time, started with unknown Performance Friction pads and quickly swapped to the blues and got better feel and no lockup. Based on my experience I'd be nuts to run anything but the Hawks.

Slightly off topic but relevant. I changed pads this past weekend at the track. On the left rear I noticed that the bottom part of the inside pad was worn down more than the top so I looked at the piston. I noticed a void in about 40% of the circumference of the ring on the piston and the void was horizontal and on the top of the piston.

With several phone calls I learned that there is a correct orientation of the void area. While I never did fine out, for sure, what it was, pictures from the internet show the void more verticle and towards the center of the wheel.

I have to assume that having such uneven wear on the pads meant that I had uneven braking, wheel to wheel. I have never paid any attention to the void area before and have never heard it discussed as an issue to check when replacing pads.

Any thoughts from the guys that really know these things?

Big Dog

I have been using Hawk blues for years. Never and odd modulation issues. I can lock up the brakes,but it is entirely manageable.


I have also never paid any attention to void area on the pistons. I should look it up in the factory service manual and see what it says.

Also the lock up. was it on both front wheels or just one side? Did it occur in all braking zones or just some.

Jim Foxx and I shared his gold #13 car at the November 3 hour enduro. We were sufferining from horrible left front lock up probelms for 3 hours. Heck we did 2 tire changes as well.

I drove the car for the last 2 hours and found that any not straight braking (trail braking turning left) would easily lock the Left front. Also really hard straight line braking could as well, but no so much. The right front was fine.

My thinking was that on Jim's car we too much front roll stiffness. (too much sway bar). That caused in the inside front wheel to lift off a bit and make it easier to lock when turning left and braking. Once we locked up the tire and flat spotted it it was even harder to preventing locking up again.

So his case I don't believe there was a brake sytem issue, but slight chassis problem that got worse when you flat spotted them once. I am not sure that pads Jim was running.

BTW.. if you got 30 heat cycles from the RA-1s you got you money's worth (or there were going to die soon anyway).

SvoChuck wrote:

Yeah, maybe I need to switch to hawks. I agree, I probably killed it once and from then on it wasn't going to get any better. Although, maybe I shouldn't fix it, that smokescreen did a pretty good job of keeping you off my butt!

Joe wrote:

Interesting, mine was front left lock up as well. All the other tires were fine.

Joe wrote:

I tried straight line braking, trail braking, it was mostly the heavy left turn but also on the right turn braking zone, though I think that had to do with what Chuck said, that it was a result of a previous flat spot.

Joe wrote:

Interesting, I have the massive tarret front bar (for now), I'll try backing it out.