kennycoulter

on the 944 im sellling, i put new pads and front rotors on.........well when the old thin rotors were on, you could tell they were warped. big big vibration and shake when braking. changed the rotors out and it ended............for a while, then now its back. what else can cause this? newer bearings too. its bugging the crap out of me and i think its wearing my pads faster than normal.

tifosiman

Hey Kenny,

You could have another problem, instead of a warped rotor. I would check your balljoints, tie-rod ends, and upper strut bearings. If any of them are worn out, they could cause some shudder in the steering wheel under braking.

Good luck!

kennycoulter

so with the new brakes it was smooth for a while......would it have done that with the other things?

tifosiman

It's difficult to say. One of the other offenders could have possibly just let go or wore out. It's not uncommon to start seeing things wearing out in sequence (ie, the upper strut bearing or tie rod end was stressed from your old warped rotor, and eventually disintegrated/died after you replaced the rotor, etc).

Charlotte944

Pull the brake pads and check the orientation of the brake piston. The working surface of the piston has a cut-away section that should face into the direction of rotor rotation.

Porsche did this to put more braking force on the trailing portion of the brake pads to facilitate even wear. If the cut out section does not face into the rotor's rotation, more force is applied to the leading section of the pad, and it will skip, causing brake and steering vibration.

TKS

What kind of pads are you using? Is the new vibration as bad as it was with the old rotors? If it's none of the stuff tifosi suggested it could also be uneven pad material transfer. Check out this Carroll Smith article for an interesting read if nothing else:

http://www.stoptech.com/whitepapers/...otors_myth.htm

Also though I've never seen it myself it's been said that new pads and rotors at the same time can speed this up.

kennycoulter

i use wearever pads form advanced auto. well i have the discs that have the continuous groove>>>>ate power groove? i figured its supposed to cleanto prevent the things that the article talked about. i have new ball joints but not installed yet....cause i figured i would have to get the car realigned. i saw that the tie rod ends are cracked. i guess i should get those in......thats probably where the swaying on the highway comes from.

tifosiman

kennycoulter

cracked boots.

tifosiman

whew! I was worried.

kennycoulter

bearings in the strut towers eh? is this on the early cars too? any suggestion on cheaper places to get the bearings and tie rod ends? im guessing everyone would suggest porsche parts.

Big E

Over / unevenly tightened lug nuts can lead to warped rotors, but doubt it would happen as fast as it seems to here.

tifosiman

Paragon!

kennycoulter

i hand torque my lugs to 100 i know the chart at work called for 96-98 but the stick we were called to use was 100 ft-lbs.

Neverendz

Your new rotors are warped. Cheapest, quickest way to verify, pull them off and have them machined (about $15- $20 a side). Reasons: Hard braking (panic stops). Cheap rotors. Rear brakes do not provide sufficient stopping, which causes more load and heat on the front.

, Bill