Braking on track after after a few laps….

[5timesturbo]

Well, I went to track day a few days ago. It was my first time tracking my car. She performed quite well and on a whole I am more than pleased with how things went. However, I did notice that after about three laps reaching 110 maybe twice each lap I noticed that when I pressed the break I would get a shimmy in my steering wheel. Once I let the car cool down and I go back out for another session, I go around another 3 or 4 times before the issue comes back. Does anybody have an idea what could be wrong??

[tschultz]

Lower control arm bushings are likely a bit worn. The track really stresses those components so maybe they haven't been replaced in a decade?

[Blue Shadow]

The front suspension, brakes and steering components are fully stressed on track and if they are not like new will give the shimmy and shake when you brake.

Make a list of all the parts that are part of those systems and give each of them a serious look if not a replacement to get the car ready for proper braking in a track setting. I've had some shimmy from stuff in the back that wasn't in the best shape at one time.

But first on the list is the lower control arm bushings as stated.

[5timesturbo]

Lower control arm bushings are likely a bit worn. The track really stresses those components so maybe they haven't been replaced in a decade?

All suspension parts are brand new. I wouldn’t track a 40 yr old car on anything else but brand new suspension parts…. Plus if it was suspension I think I would feel the shimmy consistently and not after 3 or 4 laps

[jayjaya29]

Brake pad issue. Either step up to a more aggressive pad or try to brake harder and quicker to "push through" the shimmy. Its essentially uneven deposits on the rotor which can occur if you are using a street/track pad and not a full race brake pad.

[gadget73]

^^ inclined to agree with a brake issue. I can't see how suspension parts would "fix" themselves when they cool off, but brake parts sure will.

Heat can also warp rotors which will un-warp when they cool off.

[Etip]

I agree with JayJaya29 as well. Sounds more pad/rotor like.