New Flex disks - now it vibrates! - PeachParts Mercedes-Benz Forum

crhenkel · #1 09-26-2007, 10:42 PM

Quote:

Originally Posted by Bruno_300TE

I guess you had to collapse the driveshaft to get the flex discs out? To do so, you probably loosened the big (48mm?) nut in the middle of the shaft where the front and rear halves meet.
The manual calls for 30-40Nm when re-tightening this nut. That is very little considering the size of the nut. Actually, this is on purpose as the driveshaft needs to adjust slightly in length to relieve stress. When the nut is too tight, stress may cause vibrations.
Bruno

Any ideas on how to tighten the big 49mm nut to the torque spec without the ability to get a torque wrench on it? I have two or three torque wrenches, but I can only put sockets on them and a socket will not fit on the nut with the two halves of the shaft in place and I do not have a crawfoot adapter in the 48mm size or even know if one that size exists.
How can I torque it to specs?

sbourg · #2 09-27-2007, 12:59 PM

It is an essential characteristic of oscillations/vibrations that a very small amount of initial vibrational energy 'feeds' on surrounding energy, channeling it into the vibration mode. Often, a very small correction is all that is needed to eliminate a strong vibration. In your case, NOT replacing the center carrier is the clue I would follow. Likely, even if you notice little play, the support has deteriorated, allowing just enough movement to amplify small power-line vibrations. Cruising above 35 mph requires enough power from the engine to feed the vibration if there is any weakness in the driveline support.

Steve