RB26 240z bizarre sudden vibration

[getoffmyinternet]

I was driving to work today on a totally flat road and out of nowhere heard a strange clatter like a small part shook loose and shortly after the whole car started to shake like crazy. It seems like it's a rear end thing but I'm not sure -- it just gets more violent the faster I go and is really low pitched. No other sound is heard like a bearing whine or anything. No apparent loss of power or hard clutch either.

 

The engine itself doesn't do anything out of the ordinary if I rev it under no load, but when I crawl under the car I can't find anything loose, missing, or out of the ordinary at all! I still have no idea what the clatter was. At first I thought it was a ballast coming off of a rim because I noticed one was missing, but I went to get the wheels balanced (ended up buying all new tires) and there was no change.

 

Any ideas?

[RB26powered74zcar]

Wonder if maybe a bearing cup on the rear u joint on the drive shaft might have came off? Just a thought...

 

I would raise up the car from the rear and then grab the drive shaft a try and wiggle it up and down, then move over to the half shafts and turn each wheel back and forth very slowly, to see if there is slop some where in the driveline...

[getoffmyinternet]

Yup. I was turning the driveshaft around and while it didn't seem to wiggle or look bad I finally realized the zerk fitting had come out, probably what that clatter was. So when I took it off two of the cups were cracked. Only a $20 fix

[getoffmyinternet]

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Edited August 29, 2010 by getoffmyinternet