I was recently doing some other service work and noted a slight clunk sound when rotating a rear wheel back and forth. Crawling under the car and moving the wheel I noted that the sound was coming from the center U-joint of the drive shaft. It had about 1/16 inch of play when moving it back and forth. The car has slightly less than 20K miles on it, which seems rather early for this type of wear.

Is this a known problem with these cars?

 

Kern are you certain there is play in the U-joint? It is normal to get a clunking sound and see some rotation of the drive shaft when rolling a rear wheel back and forth. What you need to do is stretch out your hands from under the car ( This is a lot easier up on a left) and grab the drive shaft near the transmission with one and and near the rear with the other and then try twisting the shaft. The u-joint you speak of and the center bearing would be between your two hands and there should be no rotation or clunking sound when you twist the shaft in opposing directions with your hands.
My SRT6 has 13,000 miles and I have a loud noticeable movement and clunking sound of the drive shaft when rolling the tires back and forth, but solid no rotation or sound when twisting with my hands while the car is up on a lift. The center bearing and u-joint are solid.

 

zip,\
Thank you for your reply. After reading your comments I went out and crawled under the car again and did some further sleuthing. As you suggested, the U-joint is tight. The noise and play seems to originate between the transmission output shaft and the driveshaft at the spline. I am very surprised that the Germans would allow that kind of play at that spline. I cannot recall noting that play in several U.S. cars that I have owned.

 

Kern,
The drive train in most vehicles have normal backlash, The drive shaft, rear differentials, and transmission connections all have a natural amount of backlash. Backlash is usually present at the connection points where 2 drive components such as a driveshaft to rear differential are connected. This connection usually uses a splined shaft that typically has a certain amount of built in clearances to allow for ease of assembly and the natural vertical and horizontal motion of the drive system during operation.
There is also a small amount of backlash present between the gears in rear end and transmission assemblies. The universal joint connection under normal operating conditions does not have backlash. If the sealed bearings in this component lose their lubricant they will rapidly degrade and begin to vibrate during operation. The noticeable sign this is occurring will result in a strong vibration sensation during normal driving. Most u-joints are sealed and do not require lubrication. However, there are some that have grease fittings which require occasional greasing. I don't believe you have a u-joint problem unless you can detect a vibration during normal driving.

 

I know on trucks if the spines dry out grease wise they wear and when they wear you get play. But on some vehicles the play will be there from lack of grease.

There are tsb's from different manufacturers where grease wasnt applied correctly during assembly. Fix is to remove the driveshaft, apply grease, and reinstall. This eliminates the clunking noise.

Also the grease can dry out over time causing the same effect. This is an age thing and has nothing to do with mileage.

You can take it as "its supposed to do that" and ignore it or you could try removing the axle and apply grease to the splines.