rear end shainking at 65+

[fireitup]

Ive tried everything, 4 diff sets of tires, whole rear axle, checked u-joints, tailshaft housing, cant put my finger on it. 99 tahoe 2wd 4door lowered 4in front 6 in rear, last thing I can think of is the helper bags but even when I air down it still shakes. If I look in my rear view mirror I can see the axle shaking back and forth, the bigger the wheel the worse the shake. Also pulled the leafs the check their bushings and they are fine. The rear leafs are lowering leafs dont know who used to make them but they are drop leafs.

 

[718frankb]

your drive shaft could be out of balance or you can have a bad pinion angle