Propeller shaft rattle

My drivetrain rattles like crazy! It's mostly when I drive at really slow speed, or when I take my foot off the throttle. It's a VERY noticeable "chunka-chunka" sound accompanied by heavy vibration.

My guess is it's the propeller shaft (or is it cardan shaft? ) or its bearings that are worn out. When I don't apply any torque on it, i.e. don't give it any throttle, it "comes loose" and starts shaking. That's my theory. Any tips on this? Does it need new bearings?

Olof Winterfjord

[Mark DiSilvestro]

Check all the rubber driveline parts. Inspect the rubber driveshaft flex-joints where the driveshaft connects to the transmission and the differential. Check the driveshaft center bearing. It's mounted in rubber too. While you're under there also check the transmission mount. If all the rubber looks solid, check the center 'U' joint. If it's loose enought to rattle you should be able to see if you can twist it. Sometimes, if the 'U' joint is seizing up, it will make a ticking or clicking sound but it won't feel loose. You may see some rust around the joint 'cross' or 'spider' but will probably need to remove the driveshaft to see if the 'U' joint is binding. If the 'U' joint is bad, it's not designed to be repaired. You have several choices -

Buy the new driveshaft section that has the 'U' joint, When I priced this part for my '72 250 in 1992 it was over $500 from Mercedes!

Find a good used one. This may be difficult as the car is over 30 years old and the 4 cylinder and diesel shafts are different.

My solution was to remove my driveshaft and take it to a local driveshaft specialist, who cut off the section with the bad joint, then welded on a new one containing a replaceable joint and grease fitting, then re-balanced the whole assembly, at about half the cost of the new shaft.

Happy Motoring, Mark

[mzsmbs]

besides inspection you could also flip the tranny from R to D and/or D to R while having the break pedal depressed (you don't want the car to move) and if you feel/hear a clunk then it's most likely a component of your propeller shaft.

Originally Posted by mzsmbs

besides inspection you could also flip the tranny from R to D and/or D to R while having the break pedal depressed (you don't want the car to move) and if you feel/hear a clunk then it's most likely a component of your propeller shaft.

It's a manual transmission, but thanks anyway

[joshhol]

I'm planning on sending my driveshaft to these guys: www.driveshafts.com
They seem to be very precise. Not too expensive.

Complete driveshaft from MBZ for my 115 is in the $800 range now.