Vibration in steering wheel when braking. Warped rotors???

cyberpmg · 02-20-2009, 05:05 AM

I seem to be having a vibration issue when braking. At low speeds (40mph and under), the brakes behave normally with no real vibration. At faster speed, gradual braking would cause the steering wheel to shake back and forth. If I'm stronger in braking at higher speed, it doesn't seem to vibrate.

I have Stoptech brakes up front and had the rotor rings replaced last year due to heat checking. I bought the rings from RacingBrake.com and used their hardware kit to attach the ring to the aluminum Stoptech hat.

Some of the original bolts were stubborn to remove and required heating up the bolt to get it out. After replacement, I noticed a few bolts loose on the driver's side and had them tightened up (and properly torqued).

I'm wondering if the heating of the bolts for removal might have caused the aluminum hat to warp. Could it be the rotor ring(s) are warped, or could it be brake pad material on the rotor that's doing this?

I'm using Ferodo DS2500 pads with the Stoptech brakes. The rotor rings are slotted. I also have the ECS S4 rear brake upgrade kit which includes a 2 piece slotted floating rotor, but I don't think the rear brakes are an issue as I've had no vibrations in the seat when braking.

Just Me · 02-20-2009, 07:21 AM

.. where they debunk the warped rotor myth ( their words) and suggest that this common problem is pad deposits?

true for almost all brakes, but ironic since oyu have STs

G

L8TE APX · 03-04-2009, 12:34 PM

Really don't know how to determine what is actually going on. There is no visable build up and the rotors only have about 8,000 miles on them. About 6-8 track days but in chcking the tempature of the rotors I never found them over 650 degrees and stock rotors should ealily handle 650.

Just Me · 03-06-2009, 03:56 PM

sand them and see if it improves. Mine alwasy do. they rarely warp.

titsataki · 03-18-2009, 09:29 AM

I heard if you perform the ST pad bend in it may help.
Otherwise take the rotors off and have them resurfaced.
If you can have them take the slightest amount of material off since I as well believe that pad deposits are the culprit of vibrations while braking.

cheers

Nick

02-20-2009, 07:21 AM	#2
Just Me AudiWorld Super User Garage is empty, add now Join Date: Mar 2003 Posts: 5,469	Have you read stoptech's web site? .. where they debunk the warped rotor myth ( their words) and suggest that this common problem is pad deposits? true for almost all brakes, but ironic since oyu have STs G __________________ glenahan@vee-eff-emaildotnet

03-04-2009, 12:34 PM	#3
L8TE APX Audiworld Junior Member Garage is empty, add now Join Date: Jul 2004 Location: Sacramento Posts: 678	I have the same problem with my B7 S4. Some say warped rotors and others it is a build up. Really don't know how to determine what is actually going on. There is no visable build up and the rotors only have about 8,000 miles on them. About 6-8 track days but in chcking the tempature of the rotors I never found them over 650 degrees and stock rotors should ealily handle 650. __________________ Audi Club Golden Gate 07 S4 Sedan 4.2 DTM Red 01 A4 Avant 1.8 MT5 Silver

03-06-2009, 03:56 PM	#4
Just Me AudiWorld Super User Garage is empty, add now Join Date: Mar 2003 Posts: 5,469	Of course you know how. Mic them. or.. sand them and see if it improves. Mine alwasy do. they rarely warp. __________________ glenahan@vee-eff-emaildotnet

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03-18-2009, 09:29 AM	#5
titsataki AudiWorld Member Garage is empty, add now Join Date: Jan 2008 Location: New Haven CT Posts: 210	I heard if you perform the ST pad bend in it may help. Otherwise take the rotors off and have them resurfaced. If you can have them take the slightest amount of material off since I as well believe that pad deposits are the culprit of vibrations while braking. cheers Nick