Rubbing sound/feel. HELP!

[E30Owner2025]

Hello everyone. I have a 1993 325i Convertible E30, 5 speed manual. My car has a cyclical rubbing sound between 5-20 mph. It comes on while accelerating and again while coming to a stop. When it comes on it feels as though the breaks are being applied repeatedly. Took it to a local shop, BMW Surgeons, who replaced the guibo, driver’s side rear wheel bearing, removed the rear axels and took the differential apart and checked ok, tested it with different tires and wheels but the problem is still there.

I hope that with the collective massive amount of experience and know-how there is someone here who can help solve the this puzzle. I will be eternally grateful for any thoughts on what could be causing this.

Thank you.

[tomstin]

Can you replicate the sound with someone standing outside the car while you accelerate of come to a stop? If so, that may give you a hit as to one side or one wheel. A brake caliper could be hanging up or maybe the parking brake out of adjustment. I would think a shop would have spun each wheel by hand with the wheels off the ground but there is another idea. Good luck!

[82eye]

get the back wheels up in the air and see if you can recreate it. if it doesn't happen than you know it will only happen under load or is isolated to the front. that will get you closer to finding the cause.

[TobyB]

When I was a teenager, there was often a cyclical rubbing sound...
that's pretty much died down, now.

I can think of 500 things that make a cyclical rubbing sound-
anything from a brake backing plate to the sound deadening touching
the driveshaft. But the parking brake shoes are always suspect...
a dragging caliper (is one wheel always a bit warmer than the other 3?)
or is perhaps a wolverine wedged in a wheel well?

There are a lot of things that the internet's good for, but
diagnosing noises isn't always one of them.

t
artificially stupid.

[E30Owner2025]

Can you replicate the sound with someone standing outside the car while you accelerate of come to a stop? If so, that may give you a hit as to one side or one wheel. A brake caliper could be hanging up or maybe the parking brake out of adjustment. I would think a shop would have spun each wheel by hand with the wheels off the ground but there is another idea. Good luck!

Thank you tomstin. Not standing outside but I sat in the back with the top down while my son drove and I could hear the noise coming from under the rear of the car. I could also feel a slight up and down movement with every rub. The wheels spin freely off the ground and the brakes checked ok. The noise fades away and completely disappears above 30 mph. Would a hanging caliper behave this way?

[E30Owner2025]

get the back wheels up in the air and see if you can recreate it. if it doesn't happen than you know it will only happen under load or is isolated to the front. that will get you closer to finding the cause.

Thank you 82eye. The shop sent me a video with the car running off ground and the rear wheels appear to spin freely so if it is the rear then it is only happening under load.

[E30Owner2025]

When I was a teenager, there was often a cyclical rubbing sound...
that's pretty much died down, now.

I can think of 500 things that make a cyclical rubbing sound-
anything from a brake backing plate to the sound deadening touching
the driveshaft. But the parking brake shoes are always suspect...
a dragging caliper (is one wheel always a bit warmer than the other 3?)
or is perhaps a wolverine wedged in a wheel well?

There are a lot of things that the internet's good for, but
diagnosing noises isn't always one of them.

t
artificially stupid.

Thank you TobyB. I’ll be sure to look for that wolverine! I agree there could be many things causing that but it’s definitely rotational. This narrows it down to the entire car minus the emblems. Presumably the shop ruled out the driveshaft, wheel bearings, diff, rear axles, and rear brakes. Can a caliper or parking brake only hang under load?

I agree the internet is not the best but I’ll take the input and wisdom anyway I can. Beggars can’t be choosers.

[tomstin]

Noises are always tough to pin down. If the caliper was hanging up you would typically notice that when spinning the tire off the ground. The shop tried another set of wheels and tires, so that would eliminate them.

Are there any witness marks in the wheel wells or fenders (spots of rubbing) or under the car?

Another thought, by chance is the noise engine speed dependent? Will the noise happen with the car moving in neutral? Lower or higher gear to change the engine speed?

[82eye]

does it happen without braking or only with brakes applied?
could be a warped rotor if it happens when applying the brakes.

[E30Owner2025]

Hello tomstin. Thanks for sticking with me. There aren’t any scuff marks on the rims, the wheel wells, driveshaft or axles.

The noise is there in both neutral and gear, speeds up as I accelerate. Considering the wheels spin once for about every four driveshaft rotations and this about the frequency of the noise, could it be the diff output shafts/gears?

[tomstin]

Final thought, lift the car by the chassis (not by the wheels), do you get the noise with the car lifted and running in gear?

[82eye]

do you get the noise with the car lifted and running in gear?

further up he answered the noise can't be replicated with the wheels off the ground and running. seems like it's in the driveline under load. i'd toss another diff in to see if it goes away.