I have a 92 coupe. I am still having a problem with the left rear wheel area. It usually makes a scrapping sound like when you've let the brakes go for too long and they start the metal on metal grind but the surfaces are smooth and I have found no sign of metal shavings or fresh marks. When I make a moving turn under slow speeds I hear a popping sound. My kids say they can hear this when I leave the driveway on my way to work everyday. I put it up on stands today and had my son rotate the tire while I was under the car looking for anything not right. I've checked for play in the wheel (bearings) and movement of the half shaft (joints) and they seem in good shape. Caliper binding? I am not sure what avenue to take to fix this , any suggestions would be very appreciated. Thanks.

What kind of pads are you using (compound) you may want to goto a softer type I have found in the past some semi metallic pads with cause this chaffing noise to occur, also bleed your lines often time your caliper piston will slowly retract if you have air in the system this with also give you the chaffing noise.One more thing check the caliper piston boot for sings of wear you will need to dis mount the caliper for this and remove the pads. another thing you can do is remove the rotor and check it for trueness place it on a level surface and use a straight edge to check for gaps or take it to you local machine shop they can spin it for you and resurface if needed....hope this helps you out a bit

Thanks jim420, that's the response I was looking for. I believe the pads are stock (on there when I bought it). As for the rest, it gives me hope. It may take me a few days but I'll give a reply either way, success I hope. :thumbright:

The popping sound is most likely the slop in the rear wheel bearing splines. Torque from the halfshafts causes them to slip slightly when you first back up, or first pull forward. It's a clunk, clunk, clunk noise. Sometimes a higher pitched noise can come from it, since it's metal galling against metal.

There really is no fix that I've found. I did finally put some tapered roller bearings in and they fit so tightly on the splines that there is no play. But all the other bearings I tried slipped.


As for the brakes, some scraping noise is normal, especially if the brakes have sat overnight and have surface corrosion on them. The pressure developed by the few feet of elevation of the master cylinder above the caliper causes a slight pressure on the pads, so they drag against the rotors. This is a good thing, and eliminates slop from the brake pedal. If you lift the front end up you should still be able to spin the wheel by hand, the actual pressure from the pads is virtually nothing. I would also make sure your parking brake is adjusted correctly.

Well, the rotor is flat and bled the brake lines and they did need it (looked like tea coming out of there), but this did not help with the noise. This is a learning experience, trouble shooting that is. Thanks jim420.

CentralCoaster, is this a safety issue I should be concerned with? I've never heard of this problem with any car before now, but I don't know of too many people who have an IRS. I searched the threads here and found the ones with the tapered bearings, I just may have to go that route. Are they difficult to put in? Thanks.

Bearing swap usually isn't hard unless the bolts are siezed up and need some coaxing. Pull the spindle nut, remove 3 torx going in the back side of the knuckle, pull caliper and rotor, and you're there.

I don't know why this seems to be exclusive to the C4. Most FWD cars use this same bearing design. Maybe it's because the C4 uses the axle also as an upper camber link which necessitates torquing the hell out of the spindle nut and clamping those surfaces together, causing everything to make noise when it does finally slip.

Not a safety issue, just an annoyance. Actually I do suspect that the slop isn't helping the drivetrain any on the racetrack.

Lubing the hell out of the splines and washers in there with antisieze or maybe grease will quiet it down for awhile.