Rotational noise from rear - 986 Forum - The Community for Porsche Boxster & Cayman Owners

bekks · 07-18-2019, 10:52 AM

2000 S 6 speed manual. 90k km
I have a noise that is coming from the rear that increases in frequency with the speed of the vehicle, but not the engine. It definitely coincides with the rotation of the wheel. Coasting to a stop seems to make it the most audible, due to the lack of engine noise. Sounds a little bit like a rubbing/grinding noise, but not like a wheel bearing and it is not discernible over 60 km/h due to road noise, although it maybe seems to diminish when cornering.
I have put the car on jack stands and ran it in gear and I can't seem to replicate the sound, I've also jacked up the wheel I suspect (right), while on jack stands, but that didn't make a difference. While investigating under the car with the wheels turning, I noticed the transmission is making a little grumbling noise, but I don't think I can hear this from in the car and the transmission makes the noise whether it is in gear or not (still need to check if it does it with the clutch disengaged).
I took the brake disc off one wheel cause it was making a little bit of a grinding noise spinning by hand. Nothing significant came out, but it was quiet when spinning by hand afterwards (that did not fix the noise I still have though).
And one other thing of note, I was on a nice twisty road 2000 km ago and came around a right hander followed by a screeching sound from the rear (I thought the car was done for), but as I coasted up another 50 m to pull over the screeching went away. Couldn't find the cause, but I think that may have been the start of the noise I am now hearing.
I realize it's tough to diagnose a sound through a forum, but I can't figure it out.

BYprodriver · 07-18-2019, 11:03 AM

If the rear wheel bearings have not been replaced they are due. They will make noise only when they are under load. Best way to hear them is to drive close to a solid wall at night when it is much quieter outside. May need to apply a load to each side against the wall to hear the source.

blue62 · 07-18-2019, 12:07 PM

+1 on wheel bearings.
Also A recent poster had a similar problem. Turned out to be coming from the e-brake drum.
He had a piece of the e-brake mechanism broken off and spinning around inside the e-brake drum.

bekks · 07-18-2019, 02:28 PM

I really don't think it is a wheel bearing, but I know that is not uncommon. Can anyone confirm that a wheel bearing was audible only at low speeds? I've always found they are more noticeable the faster you go.
I guess one other thing I did not mention (that supports a wheel bearing problem) is that it takes a little warming up (driving) to get the noise to start. I don't hear it until a few km down the road.
As I mentioned, there was something making a little noise in my drum, but that wasn't the actual culprit I'm after.
Appreciate the thoughts. I will further consider a bearing.

Anker · 07-18-2019, 03:47 PM

My experience with bad wheel braring is that the noise varies with speed, is audible at all speeds, and varies when you make turns (louder when turning one way than when going straight). They usually go bad one at a time.

Anker · 07-18-2019, 03:48 PM

I also believe you noise is caused by either a shield rubbing or from a problem in the e-brake!

BYprodriver · 07-18-2019, 06:09 PM

Quote:

Originally Posted by blue62

+1 on wheel bearings.
Also A recent poster had a similar problem. Turned out to be coming from the e-brake drum.
He had a piece of the e-brake mechanism broken off and spinning around inside the e-brake drum.

I broke one of the springs in the E-brake drums that holds the shoes while practicing 180 degree parking.

bekks · 07-19-2019, 10:41 AM

Quote:

Originally Posted by Anker

I also believe you noise is caused by either a shield rubbing or from a problem in the e-brake!

I checked closely to make sure nothing was rubbing (with the wheel off, then the brake pads out, then the disc/drum off). As I mentioned, there was a little sound that went away after cleaning out the drum, but that was not my main problem. Cornering one way now seems to exacerbate it a bit, so the bearing is looking more likely. As well as the fact that I cannot replicate the sound with the wheels unloaded.
I have a good wall to drive along on my way home today, so I will confirm which side it is coming from and then order the bearing.

piper6909 · 07-19-2019, 03:36 PM

Quote:

Originally Posted by bekks

I checked closely to make sure nothing was rubbing (with the wheel off, then the brake pads out, then the disc/drum off). As I mentioned, there was a little sound that went away after cleaning out the drum, but that was not my main problem. Cornering one way now seems to exacerbate it a bit, so the bearing is looking more likely. As well as the fact that I cannot replicate the sound with the wheels unloaded.
I have a good wall to drive along on my way home today, so I will confirm which side it is coming from and then order the bearing.

Even if you drive it along a wall, it'll be tough to figure out which side it's coming from. Especially as early on as this seems. My suggestion is that if you can't hear it when it's not under load, and there's no play in either wheel you should just keep driving it until it gets worse. Once it gets bad enough you'll know for sure which one to change.

Another suggestion is to put it up on jack stands, start it up and put it in drive or 1st. It'll turn the wheels faster than you can by hand.

dghii · 07-19-2019, 06:42 PM

Quote:

Originally Posted by bekks

I checked closely to make sure nothing was rubbing (with the wheel off, then the brake pads out, then the disc/drum off). As I mentioned, there was a little sound that went away after cleaning out the drum, but that was not my main problem. Cornering one way now seems to exacerbate it a bit, so the bearing is looking more likely. As well as the fact that I cannot replicate the sound with the wheels unloaded.
I have a good wall to drive along on my way home today, so I will confirm which side it is coming from and then order the bearing.

I think almost all of us that have had this kind of noise hunts and hunts, wonders and wonders, and then finds replacing the bearing solves all.

Your car is at an age and mileage that the bearings are suspect. Get them change and motor on!

Anker · 07-20-2019, 05:03 AM

With all four wheels on the ground, go from wheel to wheel and push and pull as hard as you can at the top of the tire. If you feel a slight clunk you have found a worn wheel bearing. Try this both when the car is cold and also just after it has warmed up.

boxster_nut · 07-21-2019, 07:02 AM

Do any of your tires have any cupping? or an abnormal wear pattern? If so, you may want to consider going to a tire/wheel shop and have them check the lateral and radial runout of the wheels.

bekks · 08-03-2019, 09:06 AM

UPDATE

Replaced the wheel bearing. It wasn't the problem.

The noise seems to have decreased and it took a while longer to come back, but it is definitely still there. This leads me to believe that it has something to do with the parts I took off (probably brakes). I am going to try to loosen the e-brake a bit.
Also, I noticed a wear mark on my e-brake cable sheath - my tire is rubbing on it. Anyone else have this happen? Stock (staggered) tire sizes.

Leo G · 08-03-2019, 09:14 AM

I had a skiffing/rubbing sound from my rear left. Especially when turning at speed to the right. And you really hear it when the window down and driving parallel to a wall so the sound bounces back.

It was the shield plate at the back of the disc just rubbing. Just needed prying back slightly.

bekks · 08-03-2019, 09:19 AM

I can hear it emphasised when driving next to a wall. I looked quite closely into everything that I pulled off, including the dust shield, and could not see anything that was rubbing.
But the noise remains, so maybe I will need to go over everything again.

Leo G · 08-03-2019, 09:28 AM

Yes it was hard to see but just give it a nudge/press away from the disc. There isnt much movement but was enough to stop my noise. Fingers crossed mate!

bekks · 08-03-2019, 12:06 PM

Definitely clear all around the dust shield.
I looked more into the rubbing on the brake cable. I can't tell for sure, but I have a few wheel weights on one spot that protrude a little towards the inside of the car. These could potentially catch the brake cable. I wiggled the cable around a bit so that it clears now. Couldn't hear anything on a quick drive around the block, but I'll give it a longer test drive tomorrow.

bekks · 08-04-2019, 02:28 PM

The e-brake cable and wheel weights seem to be the culprit. I could not get the noise to start today.