Wheel shake under braking on track

[Estoril]

This might sound simple but... make sure your lug nuts are FULLY torqued. Re-check them.

I observed this at the track once. Interesting that he didn't see this on the drive in. If this is the case - replace bolts/studs.

[uberchris]

Common issue. You have to brake harder to "push through" the vibration. Its basically uneven deposits. Brake late and harder for a session.

Well that's unintuitive, but it makes sense. When it happens I tend to brake earlier in case something goes wrong. I could see how that would exacerbate the problem.

In the meantime, I'm going to check lugs and wheel bearings and will report back if I find anything out of the ordinary.

[tcp]

I second the uneven deposits on the rotors causing the vibration. That's a common occurrence and I've experienced it at track days before. A few hard, threshold braking runs should clear the deposits off the rotors and get rid of the vibration.

[cobra]

I observed this at the track once. Interesting that he didn't see this on the drive in. If this is the case - replace bolts/studs.

Yep- mine were loose, not falling off, but actually lost torque. I would guess they were at about 50 ft-lb. Damn Zimmerman rotors...

[uberchris]

Yep- mine were loose, not falling off, but actually lost torque. I would guess they were at about 50 ft-lb. Damn Zimmerman rotors...

Ok this is interesting. I went out and measured and found that the fronts were down to around 65-70 ft-lb (from 88). I'm not sure if that would be enough to notice or cause issue?

[Estoril]

Ok this is interesting. I went out and measured and found that the fronts were down to around 65-70 ft-lb (from 88). I'm not sure if that would be enough to notice or cause issue?

At a minimum - inspect your stud threads very carefully.

If it were me - I'd replace the studs and bolts on the affected wheel. If this cures the problem - toss that hardware.

[cobra]

Ok this is interesting. I went out and measured and found that the fronts were down to around 65-70 ft-lb (from 88). I'm not sure if that would be enough to notice or cause issue?

It is normal for a nut to have a lower loosening torque than tightening torque, but it's worth looking into.

[bigjae46]

FCABs. 40k miles is old. I'd try replace them first.

DTC-70 is a better front pad.