[Shop-talk] brake shudder

[Pat Horne]

Something just came to mind. The O.P. Stated that he measured a maximum deviation of .002”. How was that measurement taken? It could have been the measurement between one surface of the rotor to a part of the car that is stationary, or the thickness of the rotor. Variation in the thickness of the rotor will produce more variation in the pedal than a warped rotor. 

As for not turning rotors any more, a local, highly regarded shop says to turn older rotors, especially OEM rather than replacing them with aftermarket rotors because the steel quality of old rotors was better. 

Peace, Pat

Pat Horne 
We support Habitat for Humanity


On Sep 27, 2025, at 12:24 PM, eric at megageek.com wrote:

John,

A couple of things, I didn't think you turn a modern rotor. There normally isn't enough 'meet' to remove them and have them be stout enough.  I think that is why you had a problem with the turned rotors so quickly.

My other question, do you have speed bumps that you regularly have to go over?  What about pot holes?  I always learned that braking while going over large bumps or pot holes is a good way to warp a rotor.

I'm just throwing these out there.  I have no other in sight.

Have a great day.

Moose



From:        "john niolon" <jniolon at att.net>
To:        "shop-talk" <shop-talk at autox.team.net>
Date:        09/27/2025 10:59 AM
Subject:        [Shop-talk] brake shudder
Sent by:        "Shop-talk" <shop-talk-bounces at autox.team.net>



well I carry tools in my suburban (shop content)
 
Mt problem is a 2008 suburban that has always had a brake shudder (warped rotor) problem since I've had it... every year it seems it's
replace rotor time.
 
This year I know I had two  never turned rotors.  I put a dial indicator on rotors and saw no more than .002 runout.. so I decided to just get
them turned just to see what difference it would make.  
 
Took them to a reputable shop that turned them and reinstalled.  First drive was thru the neighborhood with no shudder.
Second drive was a ten mile trip on freeway... when exiting freeway I felt the shudder and it seemed worse than before I turned
the rotors...
 
I'm going to tear them back down next week to check everything but wondering if there is something else I need to check or be
concerned about.  I did try stopping with just the parking brake with no shudder so that eliminates the rear rotors causing the
problem.  Pads look nearly new and fit in the caliper nicely... Caliper pistons are retracting as the should (pads are not bound to rotor when
removing wheels. Lines look ok from the outside. Caliper pins are smooth and well lubricated.
 
any ideas/suggestions/true life experiences/fantastic tales ???
john_______________________________________________

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