Vibrations during Braking

sfzBimmer · #1 (**permalink**) 03-31-2004, 02:09 PM

I just came back from a driving school at VIR and my brakes are vibrating really bad under braking now. I *think* it may just be brake pad deposit buildup on the rotor, but I'm not sure. I took some pictures of the rotors just now, what do you racers think is the problem and how can I solve it before this weekend's driving school at CMP?

note: When I rub my fingers against the rotor, I can't feel any dramatic sort of grooving or damage to the rotor. The rotor mostly feels smooth to my fingers. I'm using Powerslot rotors and Axxis Ultimate pads, by the ways...

SG_M3 · #2 (**permalink**) 03-31-2004, 08:48 PM

looks like just deposits to me. What pads are you running?

sfzBimmer · #3 (**permalink**) 03-31-2004, 09:48 PM

Axxis Ultimates. I just went out and tried the brake bedding procedures. On my way home, cooling the brakes after I redid the bedding in procedure, they didn't feel any better.

SG_M3 · #4 (**permalink**) 03-31-2004, 10:02 PM

mine did the samething with axxis ultimates, though mine went away on the street before my next de. You can always try some light sand paper on the rotors to remove the deposits.

sfzBimmer · #5 (**permalink**) 03-31-2004, 10:04 PM

The difficulty is that this happened this most recent weekend at VIR and my next DE is this weekend at CMP. I had this happen with my stock pads once, but I had enough time on the street to get the buildup off. Unfortunately, I don't have that same time. How many days of street driving did it take to get the buildup off of your rotors?

SG_M3 · #6 (**permalink**) 03-31-2004, 10:13 PM

i don't remember. I see your car is AA s/c, have you thought of stepping up to a better pad?

sfzBimmer · #7 (**permalink**) 03-31-2004, 10:16 PM

It's AA "Tuned" (I've got their exhaust, strutbars and chip). It's N/A though.

SG_M3 · #8 (**permalink**) 03-31-2004, 10:37 PM

oh, its late.

sfzBimmer · #9 (**permalink**) 04-01-2004, 08:39 AM

Considering that I only had 2 days before the CMP DE, I just bought a set of front OEM rotors and swapped those on. Problem solved. A couple other people have also said that the Axxis Ultimates are unacceptable for track use; they simply can't handle the heat which leads to uneven material transfer. As soon as they get low, I'm swapping on some HP Pluses.

SG_M3 · #10 (**permalink**) 04-01-2004, 09:04 AM

Axxis are great street pads, but they are not track pads. If your braking technique isn't the best then you will hate them.

tatawaki · #11 (**permalink**) 04-02-2004, 01:17 PM

damn, that reminds me.. I have to pick up a set of racing pads for the front. going to road race school may 1,2.