swtvictory

What could be the cause of my NEW driveshaft to vibrate at high speeds? Is it something to worry about?

LS171Malibu

Check the angle of the rear end...as far as, the angle of the input yoke. It will run smoothest at high speeds if it is the same as the angle of the engine. For example, use a magnetic protractor, and set it length wise on something you determine to be in the same plane as the crankshaft, valve cover should work. Lets say it indicates 2 degrees down. Now put the protractor on th rearend, not the driveshaft, on an area that is in the same plane as the shaft going in. It would drive smoothest if it was also 2 degrees down. Another thing to look for is the output on tranny needs to be farther from the ground than the input on the rear end. All measurements need to be taken with the full weight of the car on all four wheels on the levelest location possible.

Blake

LS171Malibu

Duh <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" /> , this is called pinion angle. It could be off if you change the ride hieght, if they goofed the mount locations on your rearend, or if you have an adjustable torque arm that has not been set up properly.

swtvictory

This is what I did all at once.

BMR K member
Heavy duty DS "which I set the pinion angle at -2.5 I believe".
Moser 12 bolt

LS171Malibu

Did you lower it? Check the angle of the engine. Keep posting, I would like to know what will fix it.

Orange Krush

Did U check u-joints ?

Poor quality u-joints could cause this !