Due to the fact that the u-joint virtually does not flex, it does all it's wear in the same position. They will often wear a small notch in that location, which will often cause a vibration at a specific speed and load.

A trick that has worked very well for me in the past is to loosen both carrier mount bolts on the carrier near the u-joint. Remove one of the bolts all the way and put a few washers between the carrier and the body, and then put the bolt back through. Then tighten both bolts.

This will cause the u-joint to ride in a position ever so slightly different from the wear point. It often will cure the vibration.

Hope this helps.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

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