Well, I had hoped my problem would be so simple but i was totally off! Upon more careful examination (parking brake shoes and adjuster are o/k), this noise is coming from under the car and is not directly related to the brakes! Although applying the brakes in reverse will cause the symptom, so will hitting the accelerator. In fact, it seems any sudden application of torque to the driveshaft will create this noise. I now suspect either the universal joint or the center support bearing! I also assume that as this problem gets worse, it will begin to make noise in drive as well as reverse?! Can anyone think of a way to narrow down the problem between the u-joint and the support bearing?? Either way, this noise is definately driveshaft related, and is coming from somewhere between the center to the rear of the car. And can anyone guess why such a problem decides to show itself in reverse first, as opposed to all the time? Are the wheels torqued more in reverse than in drive at very slow speeds? Thanks again
-travis


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'76 300D

Travis, please describe the noise in more detail. Thanks..

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Jeff L
1987 300e
1989 300e
1987 BMW 325

My money would be on the rear half shafts. These are the ones that go to the wheels. They are known for noise.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope :)
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

noise in more detail: Sounds like metal on metal friction that varies in amplitude as the wheels turn - very similar to the worn out brake pad noise. There is a hint of a "creeking" sound in there too. Definately driveshaft related. My father's mechanic took it for a drive and said either u-joint or center support bearing. Anyway i think he is a crook so i am searching for some info here. thanks again all!

BTW does a half shaft have a bearing that goes bad or does the shaft itself get worn somehow? What part of the half shaft would make noise. thanks

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'76 300D

Travis,

The half shafts have no bearings per se. They have a joint on both ends of the shaft. These shafts connect to the side of the differential and transfer torque to the wheels. Because of the independent suspension, they allow the wheels to go up and down while the differential is fixed to the body. On most American front wheel drive cars and pickups, the entire rear axle moves up and down and is spring mounted. This means that the driveshaft connecting the transmission to the rear axle must change in length and angle as you drive. With an independent suspension, the driveshaft transfers torque without changing length or angle. The half shafts are the ones that change length and angle.

These shafts are typically not serviceable by a home mechanic. If you can find a good used pair of shafts, this would probably be your best bet. Failing that, I'm sure that the parts shop on this site has them available at a good price.

Good luck,

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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

Travis, get the car up in the air and eyeball everything, driveshaft, halfshafts, center support bearing. Then go hands on. Give all of those rotating parts a good shake, move them around, twist them. If anything is bad enough to make that much noise, it's a fair bet you'll locate it. It kinda sounds like when you put it in reverse or apply the brake, you are taking the load off of a worn out component and it's telling you that it's worn out by being noisy. I hope you'll be able to find it or at least narrow it down. Good luck..

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 04-19-2000).]

thanks guys! Yuo have given me some graet ideas/advice about this. It really helps to have your thoughts on the problem! I will let you know how it goes next chance i get. Mom has put her foot down - no cars on Easter weekend! Later
-travis

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'76 300D