High speed brake shudder

[Nick Triesch]

I'm having high speed brake shudder like when you must suddenly brake on the freeway. I feel it through the peddle. Its like and sounds like going through gravel. Low speeds are fine . Around town on back roads are fine. I took the car to my favorite shop and had both front rotors turned. pads are very new I bought from Pelican. So I got back on the freeway for a test and nothing has changed. Like going through gravel. I inspected the rear rotors and they look smooth and clean. Any ideas what could cause this problem. Than you.

[RSTarga]

Front wheel bearings

[Quicksilver]

Originally Posted by RSTarga

Front wheel bearings

+1
If it isn't brake rotors then it is very likely it's precessional tramp. Grab the top of the wheel and rock it in and out and see what kind of slop it has.

[jabb]

Also check tie rod ends

[bkreigsr]

You don't identify the car that's affected.
On the M calipers, the pistons should be clocked so the trailing edge of the pad contacts the rotor first - something like 10 degrees.
Bill K

[Rodsrsr]

Warped rotors can also cause brake shudder.

[Nick Triesch]

OK, Ill check those things. Meanwhile it is back at the shop to have rear rotors turned. Sorry, its my 85 911 Carrera.

[ClickClickBoom]

New Brakes!

Even though some say bedding is not necessary, I will disagree. Have done it on Cessnas and cars, all as per the manufacturers installation instructions. My stuff was just OK, after bedding WHOW!

[Costa P]

Nick, have you done any track events recently?

Shudder is often caused by "pad imprints" transferred to the disks.
https://www.zeckhausen.com/catalog/index.php?cPath=6446_6444

[bpu699]

Yep, after several days of high speed track braking I have shudder too...

I think there is a way to re-bed the pads with quick short stops from speed....

[Joe Bob]

Could be brake pad clumping from your event. A couple up to 60 and gentle braking down to 20 a few times might clean it up. Happened to me at Willow Springs but I was able to clean them up on the cool down lap.

[Nick Triesch]

Brake shudder solved! I had the front rotors turned yesterday and the problem was still there. Today I had the shop turn the rear rotors and shudder is gone! Mechanic told me that shudder in steering wheel is front rotors, shudder on the peddle is rear rotors. Everything is good but now I have a harmonic sound while normal braking coming to a stop sign. starts while I'm braking, then noise fades away. Everything looks good. Not worried. Much better than the heavy shudder while hard braking.

[msterling]

That could be a caliper dragging caused by a piston not returning. In my case it was ancient rubber brake lines. They actually close up and restrict flow. New lines fixed that issue for me. I wonder if a dragging caliper would cause a rotor to overheat and warp.

[wrxnofx]

Originally Posted by Nick Triesch

Brake shudder solved! I had the front rotors turned yesterday and the problem was still there. Today I had the shop turn the rear rotors and shudder is gone! Mechanic told me that shudder in steering wheel is front rotors, shudder on the peddle is rear rotors. Everything is good but now I have a harmonic sound while normal braking coming to a stop sign. starts while I'm braking, then noise fades away. Everything looks good. Not worried. Much better than the heavy shudder while hard braking.

My shudder under braking was ALSO due to my rear rotors. Once I replaced them I now have nice smooth brakes. I'm still surprised by this.