vibration when slowing

[martinc]

I'm trying to diagnose a strange vibration problem on an 87 Carrera. When slowing but not using the brakes there's a vibration that can be felt in the steering wheel. When the brakes are applied, the vibration goes away. There's no vibration at high speeds, only when approaching a red light or stop sign without the brakes on. It doesn't sound like an alignment or balance problem and seems to be confined to the right side only. Maybe a warped rotor or caliper problem? Any ideas?

thanks

[NoLift911]

Have you jacked up the front and given everything a good shake to see what is loose if anything? Particularly the wheels. Bearing slop on the front wheels? Joints, steering linkages? Applying the brakes seems to usually stabilize things in the suspension that are worn or loose.

How many miles? Changed anything recently?

-Jeff

[aj88cab]

Several people have experienced the the right front caliper sticking on the Carreras. Check the tightness of the bearing. Then look at the rotor, is it original, maybe worn beyond specs, warping is a possibility. If the calipers have never been rebuilt it might be time. And while your in there you might as well do the bearings as well. Other items to look at..ball joints, tie rods, shocks, allignment. Any unusual wear on the tires?

Good luck
Andrew

[buster73]

When coasting to a stop, the toe-in of the front wheel will change slightly. This might cause a vibration if there is some play in the front suspension (wheel bearings, tie-rods, bushings). Could also be shocks or some weird wear pattern on your tire. If you can't find anything obvious check the alignment.

[bfegan]

Check to see if you have any loose lug nuts. Loose lug nuts can produce an identical symptom.

[jabb]

Look for cupping of the Tire Thread

[martinc]

Just an update: took the wheels off and the rotors are badly worn. Don't have a micrometer but they're 22mm on the outside edges and I'd say there's at least a 1mm lip so they're long gone. I'll replace them this weekend and see if that helps. I've been reading the post on removing those PITA dust caps. Sounds like an interesting job. Also, I don't have a vice so getting the 5 bolts off the outer hub will also be a challenge I guess. Any suggestions? One at a time with the other on the ground?
There's nothing loose in the suspension and the bearings seem solid with no play inward or outward so hopefully it's the worn out rotors.

thanks

[NoLift911]

"When the brakes are applied, the vibration goes away."

Unfortunately I don't think replacing the rotors is going to take care of your issue...

-Jeff

[martinc]

I think the culprit is a seized piston. I rebuilt the calipers today and the outside one on the "noisy" side was a little rusty and very difficult to get out of the caliper. It'll go back on tomorrow with new rotors so we'll see what happens....

[martinc]

All's well. I rebuilt the calipers and installed new rotors (they were in bad shape). No more noises. Thanks for everyone's help.