[m6-lt1]

I replaced my front rotors and pads (with the exact OEM pads and rotors) last summer due to a steering wheel shake while braking. After replacing them the shake went away. About a month later in the fall I did a "beginner" track day. During my second session my steering wheel would shake when braking between 60 and 30 mph. It would not shake from 120 - 65, only from 60 down. I also smelled my brakes only during my second session during this braking zone (pedal NEVER got mushy but I did change to fresh dot 4 fluid) I want to point out that the only hard braking i did was during my second session of four and it was when slowing down on the strait from 120mph - 50mph. No passing was allowed at this event. Other than that one braking zone I honestly barley used the brakes during all my laps as we were just following a pace car that would go faster each session.

After the track day I noticed my steering wheel would shake during braking from about 38 mph - 30 mph. This has been happening for a few months now. Keep in mind car is not a daily and the shaking is light. Also to rule out tire balance this occurs on both my sets of wheels I own (all season and summer set). So unless both are off I don't think this is the issue.

Today I gathered as much information I could on my vibration issue as it's not always shaking. When I first start driving and the brakes and tires are cold, It will vibrate when braking from 38-30. After driving for 15 mins it won't shake at that speed. But after driving for a half hour it will again start shaking at that speed again (keep in mind when I say it's shaking it is only while braking).

I read on here something about brake pad deposit causing shaking. So I tried bedding my brakes again today. Something I want to point out is after the rotor and pad install I was getting a really loud squeal while backing out of my downhill driveway. Once I finished backing out the squeal was gone. AFTER the track day though the squeal permanently went away so I guess originally I did not bed them in properly but the track day took care of it for me. Anyway bedding the brakes in again today seemed to make it better at first but then I started getting shaking from 60- 30mph which means it got worse. I will point out i did not do 10-15 hard brakings. Only did 4 because after the 3rd one it seemed to start shaking again.Towards the end of my drive (was on the highway for 10 minutes but had been driving a total of 1:15 hours) it stopped shaking at any speed.

I'm at a loss right now as it seems that brake temperature imho has a lot to do with my steering wheel shake while braking. I've never heard of this happening though. My questions are below.

1) What do y'all think my issue is?

2) If I warped my rotors, can I do another track day on them? The shake isn't that violent and if it's not a safety issue I don't really care until it gets worse.

3) If I buy new rotors again do I need new pads? These pads have plenty of life on them so I'm a little reluctant to throw them away. If I have to I understand as the surface may not be smooth is what I have read a bit in a short search

[Wuiquen]

You said with the new rotors and pads, the shaking went away. How long did you test new rotors and pads? Long enough to ensure the issue went away?

Given you've tested two sets of tires and wheels, the problem is not your balancing.

I would say the issue could be steering rack but again if new rotors and pads fixed the problem. I would try that again and see if the shaking goes away before starting to go deeper.


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[Jeb114]

OEM rotors and pads are not made for track days. If you're going to track, you need upgraded brake equipment made for it and get use to changing rotors and pads often. Sounds like you put in a lot of heat in the rotors and warped them and the constant shaking will damage suspension parts and cause wheel hop (dangerous). Also, if you change the rotors, you should change the pads. You may need to check the Calipers I have seen too much heat damage them.

[MatthewAMEL]

Originally Posted by Jeb114

OEM rotors and pads are not made for track days. If you're going to track, you need upgraded brake equipment made for it and get use to changing rotors and pads often. Sounds like you put in a lot of heat in the rotors and warped them and the constant shaking will damage suspension parts and cause wheel hop (dangerous). Also, if you change the rotors, you should change the pads. You may need to check the Calipers I have seen too much heat damage them.

OP-



The OEM SS pads and rotors are fine for medium track duty. You need to get better fluid, but that's it.


You really can't 'warp' rotors on track. Rotors will crack before they warp. If you get them hot and then drive through a puddle, you can damage them.


Almost certainly, you just have some uneven pad transfer from insufficient cool-down after tracking/not bedding. You can get similar symptoms if you 'canyon run' or other spirited driving and then park the car with hot brakes.


You can go through the bedding procedure again. But stick with the procedure! It's not uncommon to see sparks shooting off the pads while bedding. You should have a strong pad smell if you are doing it right. After bedding or tracking, the most important part is not parking the car while the brakes are raging hot and NEVER set the parking brake after a track session.


If you go through all that and still have vibration in the steering wheel, get your alignment and wheel balance checked.

[m6-lt1]

When I swapped the pads and rotors the first time, I tested that the shaking went away while braking multiple times. This time I’m not sure if it’s warped rotors because it’s at a lower speed and isn’t shaking as violently.

I went with oem pads and rotors because I figured as a beginner I would not get to their limit and I’m confident I didn’t because all we were doing was following a pace car. We were not going all out. I got stuck behind slow pokes sessions 3 and 4 so I barley had to brake after the long straight aside from session 2.

I’ll try the bedding again. I think Matthew is right. Maybe I should really stick to the bedding procedure. The only other thing I was thinking was I possibly have a bad wheel bearing? Only thing is I don’t hear any wheel bearing noises (had to replace one on my daily last week so I know what it sounds like). I guess there is a slight chance both wheel and tire sets are slightly out of balance but I’m not sure as that would be very unlikely.

Also I want to point out I checked for vibrations while driving and not braking and did not feel any between 1 mph and 100 mph today. Drove really smooth at all those speeds so I can’t figure out if I have a suspension issue or a wheel balance issue since it doesn’t happen when NOT braking.

[m6-lt1]

Also we did not get cool down laps so you may be correct Matthew. By the way I did not use the e brake when parking after sessions. I also have not hit a puddle with the new rotors because the car no longer sees rain.

[dpevans]

stock pads and rotors are fine for moderate track days. I personally would upgrade the pads to a more aggressive pad for track days and you must use track fluid with a high boiling point and do a complete flush. Pull the tires off and torque the rotors and check for run out. If you have run out then take scotch brite pad and clean the rotors real good with brake cleaner and if they still have run out then have them turned down. You should have plenty of material to turn them. Bedding the brakes will not stop a vibration unless you bedded them improperly, the purpose of bedding in the rotors so material from your pads will deposit on the rotor and increase grip when you apply the brakes. When you purchase track pads pay to have them bed in the pads so all you have to do is bed in the rotors. Another thing to check is do you have rubber chunks stuck on your tires, I have had late sessions if you get out of the groove you can pick up chunks of rubber and it will make the wheel shake and I had to scrub the tires hard to get it all off. Another thing to check are the rotors fully bedded, if you only did about 3-4 hard brakes I doubt they are fully bedded and you really don't need to bed the brakes for street driving, cause after you drive for a few days all the material wears off anyway. What you could have experienced was uneven material build up on the rotor. Good luck and get a good set of aggressive track day pads, I have the JL9 single piston with GLoc R8/10 with SRF fluid and they hold up well so I know your 4 piston Brembo are more than good enough for track days and don't be afraid to stand on them during track days. I put my pads on and bed my rotors in two days before an event cause man they squeal like crazy and leave them on for 3/4 days after and the rotors will clean themself with normal driving.

[Vivid_O_1LE]

I think if you rebed them properly you will see your problem go away. When you bed the brakes you should definitely smell them. Bedding brakes properly can be tough if you live in a bigger city like I do. I usually go out around midnight and do it so I can actually find some clear road.
Also, as others have said, usually after a track day things can feel not balanced because you tend to get a lot of hot rubber melted on the wheels and on the tires. That’s probably not the case for you now since it’s been ahwile and I’m sure you’ve cleaned it up.

[95 imp]

https://brakeexperts.com/how-to-brea...by-step-guide/

[ctrlz]

Originally Posted by m6-lt1

Today I gathered as much information I could...

2) If I warped my rotors...

You didn't gather enough information.

Rotors do not warp, they develop thickness variation. Typically this is due to uneven deposition of friction material. This can be confirmed via measurement off the car with a micrometer.

https://www.bendix.com.au/bendix-new...n-dtv-issue-14

https://www.ipdusa.com/Articles/528/...4aArJAEALw_wcB

[m6-lt1]

Seems like the general consensus is to rebed them in fully this time while also checking for runout. Did not know about runout until this thread. Also I do think I have some rubber chunks on my summer/track set because I was getting very slight vibrations at around 60 mph while not braking with that set so I might have to clean them up (do not have those vibrations with my winter set). Definitely learned a lot in this thread and I appreciate the help. I’ll have to drive an hour into the country in order to perform the bedding correctly/have enough space.

[m6-lt1]

Well rebedding the brakes did not work. I’m positive I warped/damaged the rotors. Yes I read the articles that talk about how it’s hard to warp rotors but I still think it’s very possible. If it wasn’t, mechanics wouldn’t tell you that your rotors are warped when you tell them your steering wheel shakes when braking. I didn’t mention this originally but I did not install the brake ducts prior to the event. I wanted to but I just couldn’t find the time and when I installed the new rotors unfortunately it was a rainy day and I had to drive the car home so that’s why I didn’t install them then (of course by the time I was done the rain cleared so I could have installed them).

Rebedding the brakes actually made it worse thus I believe I truly have warped rotors. No I did not drive through a puddle with hot brakes and no I did not hold the brakes when coming off the track at the end of the sessions nor did I engage the e brake when parking my car. I think not installing the brake ducts did me in. A little disappointed at myself for that but life happens. I think that will probably be my last track day because I can’t afford it if I have to change brakes after every track day (unless the ducts make that big of a difference).

There is a slight chance both wheel sets have balance issues so I’ll get one of them rebalanced in the spring and see what happens. But the fact that rebedding the brakes made the wheel shake at a larger speed range tells me my rotors are actually warped. Also the fact that the vibration developed while braking from 120-60 on my second session tells me something in the braking for overheated (wasn’t the fluid because I changed to dot 4 and the pedal remained firm.) the pedal does not pulsate. Now I don’t know if that means the rotors are fine or bad. Google didn’t give me a direct answer to that.

I haven’t checked runout but I don’t have the tools to do so. I don’t think it’s that because the brakes were fine after installing them and driving on them for a month prior to the track day.

[dpevans]

Originally Posted by m6-lt1

Well rebedding the brakes did not work. I’m positive I warped/damaged the rotors. Yes I read the articles that talk about how it’s hard to warp rotors but I still think it’s very possible. If it wasn’t, mechanics wouldn’t tell you that your rotors are warped when you tell them your steering wheel shakes when braking. I didn’t mention this originally but I did not install the brake ducts prior to the event. I wanted to but I just couldn’t find the time and when I installed the new rotors unfortunately it was a rainy day and I had to drive the car home so that’s why I didn’t install them then (of course by the time I was done the rain cleared so I could have installed them).

Rebedding the brakes actually made it worse thus I believe I truly have warped rotors. No I did not drive through a puddle with hot brakes and no I did not hold the brakes when coming off the track at the end of the sessions nor did I engage the e brake when parking my car. I think not installing the brake ducts did me in. A little disappointed at myself for that but life happens. I think that will probably be my last track day because I can’t afford it if I have to change brakes after every track day (unless the ducts make that big of a difference).

There is a slight chance both wheel sets have balance issues so I’ll get one of them rebalanced in the spring and see what happens. But the fact that rebedding the brakes made the wheel shake at a larger speed range tells me my rotors are actually warped. Also the fact that the vibration developed while braking from 120-60 on my second session tells me something in the braking for overheated (wasn’t the fluid because I changed to dot 4 and the pedal remained firm.) the pedal does not pulsate. Now I don’t know if that means the rotors are fine or bad. Google didn’t give me a direct answer to that.

I haven’t checked runout but I don’t have the tools to do so. I don’t think it’s that because the brakes were fine after installing them and driving on them for a month prior to the track day.

Take them off and have them turned down. Should be no more than 10 bucks a rotor. Start with the front two.

[m6-lt1]

Originally Posted by dpevans

Take them off and have them turned down. Should be no more than 10 bucks a rotor. Start with the front two.

Thanks I’ll try that. When originally installing them I did clean the hub as best I can which I believe helps prevent runout. I’ll try harder this time.