What is this noise from? - PeachParts Mercedes-Benz Forum

mplafleur · #1 05-12-2003, 09:04 PM

I have this noise up front that sounds almost like worn disc brakes, but I just replaced the pads and the noise is still there. (The pads did need replacing, I was into the sensor) Could this be the mid shaft bearing? It sounds like metal to metal and is most noticeable at low speed. I opened the door while driving and it did not seem to noisier. While I am driving it seems to come from the passenger side. Maybe the right front wheel bearing?

itb76 · #2 05-13-2003, 09:49 PM

The best way I can describe the noise my mid shaft bearing made before it let go, is it sounded like a turboprop airplane taking off, only not quite as loud. Obviously it varies with vehicle speed, and it was much worse in cold weather. Eventually it would go away as the car warmed up. It did not seem to come from any specific area of the car. If it sounds like this check it out right away, before the car strands your wife and kids like 400 miles from home. Mine let go at 110,000 mi. for whatever it's worth. The wife was not happy.

A wheel bearing typically sounds like a really bad tire, and gets worse in mild corners compared to straight on. Yours sounds more like a wheel bearing, though it's hard to say without hearing it.

Hope this helps.

mplafleur · #3 05-14-2003, 12:40 AM

That's what I'm thinking too. It's not a whirring noise, more of a grinding. I really thought it was my pads and I'd gone to metal. I'll have someone else drive while I open the passenger door and listen. I should have rotated the hub while I was replacing the pads.

itb76 · #4 05-15-2003, 12:40 PM

Do you hear the noise only when braking, or all the time? Does it vary in intensity as you go around turns? If it's a wheel bearing it should be louder inside the car than out; I doubt you'll hear anything with the door open.

mplafleur · #5 05-16-2003, 04:43 PM

It's funny that you ask, because I could hear it while rolling; then when I opened up the door, I could barely hear it at all. With door closed, no brakes, it sounds like it is coming from front passenger side. Just the general direction.

I ordered a set of bearings. They always need replacing at some time or another. My wife and daughter are driving to Chicago next weekend for a soccer tourny and I need to have it resolved by then.

mplafleur · #6 05-19-2003, 08:54 AM

Well, It's the mid shaft bearing.

Wheel bearings would have been much easier to replace. It's the bearing at the front of the rear drive shaft.

Does anybody have the r&r procedure for this?

mplafleur · #7 05-20-2003, 09:38 PM

Well, I got the old one off and the new one is on. But, I have to tighten everything up and I don't have the torque specs. I need he numbers for everything from the differential up to the transfer case.

Thanks.....

mplafleur · #8 05-21-2003, 05:00 PM

No one can help me with these torque values? I'd like to get this this put together.

mplafleur · #9 05-21-2003, 10:02 PM

Ok. Never mind. I'm done.

I tightened the allen heads at the transfer case to 40 ft-lb and the hex bolts at the differential to 60 ft-lb. The nut at the end of the short shaft got tightened as much as it could go. ( the one hiding behind the u-joint)

itb76 · #10 05-23-2003, 10:51 PM

Sorry Michael, I've been repairing my racecar for the last three weeks and have not visited the site in a while. The torque values you used seem reasonable. Others who have posted to the Tech Help forum have mentioned that the key to the input shaft nut (the hidden one) is to torque it the same as it was, as this affects preload on the differential. Since that's awfully hard in practice, a shortcut would be to make alignement marks before removal (yeah, too late now).

I'm not sure wheel bearings would have been easier. I believe they are the pressed onto the hubs like front wheel drive cars have. My book says 3.4 hours per side for the fronts.

Anyway I'm glad you changed it before it let loose!