: New wheel shimmy on braking



Mowgli
07-14-05, 04:25 PM
I recently noticed a slight shimmey in the steering wheel upon braking at highway speeds. 8k on the odo and I don't recall it being there before.

It is also only a passing vibration, starts at initial braking then smooths out and disappears in less than a second.

Did I warp a disc or could it be the runflats wearing? I'm thinking the latter.

...or something else?

ctsvett
07-14-05, 04:35 PM
warped rotors or tires out of balance.. when was the last time you had the tires balanced? are they wearing weird?

Reed

bryce3
07-14-05, 04:47 PM
I got the samething going on with my car :banghead: . I recently replaced the tires but didn't get a wheel alignment:hmm: . I am taking it in tomorrow to see what it needs. I will post an update as soon as I get her back.
-Sean

Florian
07-14-05, 04:53 PM
rotors.

F

Mowgli
07-14-05, 04:58 PM
Had a puncture in a rear which I had plugged at the dealer - who kindly scratched the rims taking the runflat off... :banghead: - but that was a couple hundred miles ago.

I'll check the wear pattern after work here. Have not rotated or rebalanced them since I bought it. I've not noticed increased road noise, pulling, alignment issues or steady state vibrations.

In my previous experience with a warped disk I felt it all the way to stop. This is a transient event. I hope its balance or tire wear and not a warp.

Redline CTS-V
07-14-05, 05:08 PM
If it only does it when applying the brakes it's gonna be the rotors... One or more of them is warped slightly... Going to need to be machined...

RobzBLKV
07-14-05, 07:17 PM
Not necessarily machined. Try bedding them in if you can find a deserted road. Sometimes that will wear the deposits off and the shimmy will go away.

Last time I said this here, someone jumped all over me, but it's true, so I am going to say it again anyway. Rotors *usually* don't warp. You usually get uneven deposits on the rotor that cause the shimmy feeling. People generally explain that as "warped" b/c people are lazy and the details don't really matter. If a rotor was truely warped, machining probably wouldn't fix it in most cases.

You can sometimes get rid of the shimmy with an aggressive bedding in process or by using track pads for a few days (although that will typically cause more aggressive rotor wear as well). I will try and find a link to my favorite bedding in instrcutions.

RobzBLKV
07-14-05, 07:23 PM
Here's the Zeckhausen link:
http://www.zeckhausen.com/bedding_in_brakes.htm

And here's one from the faq that come up in google:
http://www.cadillacfaq.com/faq/answers/bedbrakes.html

urbanski
07-14-05, 07:47 PM
i bedded mine and i still have a wee shimmy, light braking, at speeds above 60
not worth the trip to a dealer, very minimal

Mowgli
07-20-05, 10:47 AM
UPDATE: After much experimentation I noticed I did have a steady state shimmy at 68mph. But only at that mph. Never noticed it before because well I never drive 68mph. Going to do brake bedding anyway then rebalance the wheels.

sharky1
07-22-05, 05:02 PM
hey, I have the same shimmy at 68 mph....just had the wheels rebalanced, still have it....have you found a cure?