Well I've been chasing down some vibration problems for awhile now but to no avail. The car is a 2004 M6 with 97k miles. Recently I have replaced tires, shocks, rotors and pads, and 4 wheel alignment in that order. The vibrations and sound were there before any of these so I do not suspect any of the new parts to be an issue.

I have quite a few questions but let's just go one at a time to narrow some things down. I will admit I have atleast two different things causing vibrations and noises, some when the car is running and some even when it is not.

My first question is very simple. When off the ground, if I spin either of my front tires they sound like a slight grinding, as if the pads are scraping the rotor. There is nothing loud enough to hear while driving either under load, letting off, braking, turning, etc. This leads me to believe it is not the wheel bearings since I've heard they make quite a bit of noise when going down the road. There is also no play at all when grabbing the tire at 12 and 6 o'clock. So how can I tell if I have a problem with my calipers? Or do you believe it is something else?

 

the bearings can be noisy and have no sideways play in them so they can be going bad and making noise or vibrating with no play. If the noise or vibration gets a little louder when you are making a turn, then that is a sign of a bearing going out. Sometimes it is hard to tell if it is front or rear.

other than axle shafts or something internal in the drivetrain, you are about at the short list of what it could be. If it is brakes, the noise will change when the brakes are applied. How about the e-brake? could a pad be off one of the shoes? If you pull up on the ebrake lever when rolling and the noise changes, that could be a check too.

 

Well the noise is definitely there when I spin the fronts while up on jack stands so it is definitely the front.

As for vibrations, I have atleast one that is either rims or suspension, and then another that is exhaust or driveline. I say this because I have tried while going down a slight hill at normal speed to disengage the clutch (pedal in) and turn the car off and there is LESS of a vibration but still definitely one. So the only things rotating at that point are components associated with the wheels (rims, rotors, hubs) as well as any suspension pieces that are travelling. Could be a tie rod but again I have checked play at 3 and 9 o'clock and nothing that I could tell. I also checked all of the fasteners and they are all snug and even lubed up all of the bushings.

Then there is an additional vibration when the engine is running which hopefully is just the baffle that has come loose inside my muffler (I'm going to see if a shop can open it and weld or remove it tomorrow or Thu and also road force balance the wheels). I can feel it around 1200-1400 rpm when sitting still with the clutch disengaged. It's hard to tell whether it is rpm or speed related, neither are really definitive.

When I hit the brakes the vibration USUALLY gets worse. But I saw usually because sometimes there is only a slight vibration and hitting the brakes makes it go away. I know it's weird, but I've been doing this for months so trust me I have done this a ton of times trying to diagnose. As far as the vibration while engine is running I'm pretty stuck on exhaust baffle or much worse... torque tube couplers.

And I might as well add that I do hear a clunking occasionally which seems to come from the driver rear but maybe driver front or even both. I only hear it at slow speeds under mediocore roads but suprisingly not real bad roads.

Anyway, I'd like to focus on the stuff that I can tell when the car isn't even moving first. There's no use troubleshooting engine ON when the issues compound on each other.

Also, when driving I feel it most in steering wheel which should point to wheels not driveline but the enitre car does shake. I noticed I could see the passenger backrest vibrating while driving the other day. Luckily, it is LEAST felt in the shifter so hopefully not the torque tube couplers or bearrings.

I apologize this is so long, which is why I'd like to troubleshoot one thing at a time now.

So does anyone else have comments on the front wheel noise when off the ground and turned? Paging Rick, Eric, etc.

 

I had the same problem and found it to be a bad front wheel bearing. replaced it and no more problems.

 

Do you mean the grinding sound when spinning the wheel or the vibrations too?

Can you recommend a place to buy new ones? PM me if you prefer.

 

Anyone heard of GMB for the wheel bearing/hubs? They can be found for under $100 each or should I shell out a good deal more and go with Timken for $150? Or Moog for around $125 each?