cjoenck

This is going to be tough to describe... I am getting pretty significant mechanical noise when rolling and I started a process of elimination. It is probably not the engine since the noise is not rpm specific and the nose goes away when car is stationary with engine running. I just changed oil, atf, final drive, and adjusted valves. It does not seem to be tires since the noise does not change with different road surfaces. It is speed dependent but not massively. The wheel bearings are new (less than 400 miles), the rear axles are newish with less than 3,000 miles on them. I cleaned the brake calipers and none of the pads are binding. The brake fluid needs changing as it is 2 years old. So what else transmits rolling noise? Could this be an indication that the upper shock mounts are going? The rubber is the original I believe. What else am I missing?

964Andrew

Rolling noise on mine turned out to be bent wheel. There was no vibration BTW, just noise. After straightening the wheel the noise went away.


Thanks!
Andrew

cjoenck

Interesting. I had not thought of that. How do you "measure" for a bent wheel? I assume a visual inspection won't work for the novice.
Oh, and the engine and transmission mounts are also new. Less than 100 miles on them.

964Andrew

Take the wheels to a reputable tire shop, they can check that no problem. OEM mounts or aftermarket?

Thanks!
Andrew

Navaros911

I presume you had your wheels on and off a few times... Which makes it less likely what I'm about to say adds any value.

But have you checked that the lug nuts are tight all around?

Dick964

After replacing the wheel bearings, did you tighten the nut to the torque specifications with a torque wrench ?? (I don't mean the 5 wheelnuts on each wheel here...)

BR,

Dick

cjoenck

Yes, I did tighten to spec all around. I usually leave a torque wrench on my driver's seat when I have the wheels off to remind myself to tighten lug nuts to spec of 130 Nm. 😊 Tire pressure is 36 psi all around on 17 inch rims (205/50 ZR 17 front and 255/50 ZR17 rear).

cjoenck

That's a good question. I had my mechanic do the replacement for me but I have known him for over 10 years and he has a great reputation in the Chicago area ( Sol Snyderman @ Perfect Power). I have to assume they are to spec but I have no evidence for that.

Dick964

Ok, ask your mechanic...
Either the bearings are to loose or too tight if you did tighten the nut 'on feeling' instead of using a torque wrench (460 Nm....without grease on the bolt or nut !!)
The bearing will start to make a humming noise not long after you install them without setting them to the right torque.
And the 'nice thing' of it all is that you (often) will not feel any play in the bearings while they make this humming noise. Over time the noise will become louder.

Greetings,

Dick964

Gregg-K

I went through something similar a few years ago on my C2. Figured it "had to be" either the rear wheel bearings or the tires. Tires sounded far fetched, so we went for new wheel bearings ... which made no differences at all.

Replacing the rear tires cured the noise 100%
... Gregg

cjoenck

Wouldn't the tires create different noise based on road surface? Concrete usually sounds different from smooth asphalt for example.

Has anyone any idea how long the upper shock mounts last? I am talking about (10) in the relevant PET, i.e. the rubber piece that isolated the shock assembly from the chassis.

Thanks.

Gregg-K

Different road surfaces do sound different, but the tire noise I'm talking about was a rumbling that sounded just like bad wheel bearings. So much so, that we replaced the wheel bearings first, only to discover it made no difference ... the rumbling noise continued with the new bearings. New tires ,,, and the rumbling disappeared,
... Gregg

964Andrew

+1

Peteinjp

Same here- Old Advans were loud and rumbling. New tires were nice and quiet.

Pete

cjoenck

I think I found the issue. The upper shock mounts were toast. Road noise getting transmitted into the tub.

Old on the left, new on the right

The issue is a completely compressed mount.