Put a 4" Skyjacker lift on my 2dr last weekend and have developed a vibration between 15-40mph. Above 40 it seems to smooth out. I have had the front end aligned and have removed the front drive shaft but still have the vibration. I have an aftermarket rear drive shaft so I know it is ok. I did not have the vibration prior to the lift. I believe it is just the tires because I also rotated them at the same time. They are Duratracs with about 6,000 miles on them and they were rotated at 3,000 miles.

Any advise or suggestions?

 

Check your pinion angle on your axles. I believe the front is +2 & the rear is -2. There is a happy medium between your caster & pinion angle.

 

will do.....thanks

 

An aftermarket DSs will still vibrate if operating at the wrong angle. If you put a 4" lift and didn't rotate the rear axle to make up for the lift, you can get the type of vibration you are describing.

A DS vibration feels a lot different than an alignment or tire balancing vibration.

 

I have a similar problem, but it happened when I put 35"s on, steering wheel vibrates at 40-50 mph, other than that it's fine. Discount tire balanced everything for me, didn't have it while running my 3" lift and 33"s

 

the lift came with lower control arms so the axles should be centered but I will check.

 

You need upper rear control arms to properly set your pinion from what I'm told. Especially a 2 door.

 

It came with fixed arms, not adjustables, correct? If so, you can't change the caster/pinion without adding components. But the angles should be decent for both axles, or as decent as a single set of new fixed arms can make them.

Try rotating the tires again and/or having them rebalanced. If there is still a vibe, re-install the front driveshaft, pull the rear and drive around in 4wd. (no auto-locker up front?)