My 2007 Vanden Plas has developed a hum in the back end. No vibration or any other symptoms. The hum is speed related – the faster I go the louder it gets. And it’s getting worse.
I sourced the correct differential fluid and plan to get the car up on jack stands and change the fluid while looking for metal particles and see if everything is tight there. Can I check the rear wheel bearings just like you do on the front wheels? Checking for any play both vertically and horizontally. Anything else I should be looking for? Fixing it is going to be beyond my abilities but if I have to take it to a shop I want to have a pretty good idea of what’s going on. Thanks for your help.

 

Yes, basically you can check the rear wheel bearings the same way as the front ones. You need to put the gear into neutral and make sure that the parking brake is off.

What you cannot check as nicely as at the front is how free the wheels turn, as you have the halfshafts and the differential bringing in some resistance.

Best regards,

Thomas

 

If a seal has gone on the rear axle water can get in and rust the bearing in spots. This will progressively get worse without any wheel play until really bad. It starts just as a noise that is speed related and finally turns into a rough grinding noise, still speed related, and then you will have the wheel play along with it.

 

I put my SV8 on a lift and let it idle in gear making sure it couldn't come off lift. I got underneath and listened to all the bearings, axle, diff side bearings and pinion with mechanic's stethoscope to isolate which bearing. Not recommending, just saying it's what I did.

 

Luv2fly, did using the mechanic's stethoscope work? Were you able to isolate the bad bearing?

 

A pitted bearing may not make any noise unless under load.