So earlier this summer, did an event on used brakes at NJMP and I had some shaking in my wheel when I brake'd above 100mph, so figured I had warped rotors and it was time to replace everything.

So July do my next event on all new brakes (rotors & pads f/r , bedded them like I always do), and was frustrated to feel the issue didn't go away even with all new brakes. Really only happens when in 5th gear when I'm above the 100mph mark. So, had a friend take a look at it while I worked all week, he said gave it a new alignment but steering components seemed to be snug, as he couldn't replicate the issue in NYC area.

Did NASA event yesterday at Thompson, only on front straight do I go from 120mph down to 60 or so, and BAD wheel chatter/shaking occurs. I don't want to do another event this way, so trying to figure out what it could be.

Ideas beyond warped rotors?

 

Oh and I should add, when I MASH the pedal, it's not as bad as when I give it 50% pressure. On front straights I typically start braking a bit early just to make sure I have good pedal feedback, I'm not racing so why push it. But, after getting frustrated I just started braking later into Turn 1 and found that really jamming my foot down seemed to make the shake less violent.

And like I said, rest of the track in the 50 - 90mph range, doesn't really occur.

 

when i had this issue, it turned out to be a combo of deposits on rotors and possibly sticking piston. check the condition of your dust seals.

i wound up doing new rotors/dtc 60's/and rebuilt the calipers with racing brake bits all at once to take a big swing at it and solved it.

 

sticking piston could be a cause, when I'm driving at low speeds I can barely hear a metal on metal contact, but when I brake it goes away, meaning it's brake related. Could be a piston not fully depressed, and causing my brake pad to just be barely touching the rotor. There's no scoring on the rotor however

 

Could be pad transfer still if your using pads not made for that range or rotors that warp easily, should be able to look at the rotor and tell. Other things could be the wheel bearings, do the 12 and 6 test shaking the tire back and forth holding on the top and bottom to see if it has play. The more pressure on that point (eg fast) the more pronounced the symptom usually.

 

Pads are DT60's with Centric Rotors, but like I said the big thing here is it's done it on old brakes, as well as newly swapped pads/rotors, so trying to determine cause outside pad/rotor

Going to order a caliper rebuild kit for the fronts today and try that this weekend.

I've had wheel bearings go bad in cars before, and typically it's a very distinct noise, but it's definitely possible

 

I had this happen with a wheel bearing as well. The owner before me hit something, a pothole, who knows. But it put a flat spot in the wheel bearing. It didn't act like a bad wheel bearing. But it did cause some weirdness at high speeds. Worth looking into.

 

I had this issue before I rebuilt the brakes. Heating the brakes up would cause it to go away but the first 120-80 stuff would be a wild ride. Since the rebuild I have had no issues.

 

Subscribed - Ive had very similar issues at Thompson in my X lately. I tossed on some cheap Centric's as I related the issue to rotors, but was a bit thrown off when it came back at the very next event.

I just ordered new Girodiscs, ST43's and dust seals - the front calipers may get a rebuild while were in there too.

I have come to the conclusion that Thompson is very hard on our cars, its a pretty physical track compared to a lot of the others in the North East too.

 

thompson is extremely tough on brakes. im still trying to figure out what my issue was this weekend. even got to take the run off at turn 1.

anyway - OP's issues sounds exactly like mine. i wouldnt be surprised if the dust seals are hard as a rock and not allowing smooth travel. id recommend the racing brake hi temp silicone boots. i run their full package with stainless pistons and all and love it.

 

Can you link me? I'm trying to solve this asap before the Glen next month

 

Off topic however, at first I didn't really enjoy Thompson, but 4th & 5th sessions once half the field went home, I really loved it, especially 9 - 11, such a fun section.

 

9 through 11 is fun once you figure out how to take it without braking.

http://www.racingbrake.com/Save-10-o...p/bm-41bsp.htm

cant find the hi temp seals desperately on the site, just call em.

 

9-11 is a blast, you can carry a ton of speed through 2-3 also.

Nate/boost; are you guys doing the NASA event at WGI?

I may order up that rebuild kit/stainless pistons from RB while Im at it.

 

Could be you need new rotors or you have bad wheel bearings