Driveshaft Vibes? Maybe.

[sailbrooks]

Alright, I have had a chance to get my jeep back on the road and drive it around locally (it has been in the shop for a while.) I have been knocking down the minor issues (PS pump (PSC swap), leaks, O2 sims, vibrations and so forth.) I am down to a "pulsating" vibration above 65 MPH (in 2WD.) It changes in tone as I increase speed. I am guessing that it is the rear driveshaft.

Here's a little helpfull info: the rear is a dana 60 from a 79 f250, I retained the 46RH transmission and mated it to a rubi 241 with a flange/vibration type dampener (stock rubi) on the rear output. The driveshafts are were made by driveshaft superstore. They said that they are balanced. There is plenty of travel in the slip yokes and the angles are not too bad. Although the rear pinion is not pointed directly at the rear output because I was worried about lube cycle in the diff. Could that be the problem? BTW the rear shaft is double C. at the case end. The front shaft is not a D.C. type shaft for some reason. I did lude all of the fittings on the shafts. You are supposed to (according to the tom woods trouble shooting page) fill the slip yoke jerk fitting until lube comes out of the relief hole (I didn't fill it to this point.....maybe that is my issue?) The jeep has been optically aligned and the specs are good.....The tires all are balanced out to 0.00 for the second time. Any ideas or input would be great!

My next step is to remove the rear shaft and see what it does in 4H @ 65.

[Green Mountain ZJ]

Correct the DS angle, overfill your diff (park on a hill) and check for vibes again. TW also says that the double cardan should only be off 1 to 2 degrees max. I put mine right to zero to allow for differences in acceleration, braking, suspension cycling and so forth. Works great. I would start there because it is free and a likely suspect. Good luck.

[sailbrooks]

True.....I figured that was the issue. I had the misconception that DC DS's could operate at funny angles.....

[Green Mountain ZJ]

You are practically right next door. That sounds like a build I would like to see.