new vibes

Hi,

I have a '98 w/selectrac, about 80k ago I installed an re 4.5" lift and a Currie/Six States sye/ds. I shimmed it, minimal vibes, all was well.

Well now, a really bad vibration had developed from about 50mph and above under acceleration (when I lift my foot from the accelerator pedal, it disappears). If the the shims originally corrected the problem five years ago, why would the vibrations all of the sudden develop? Could it be a u-joint or possibly a bearing in the rear end or tc tailshaft?

Most important for now, can I remove the rear driveshaft and still drive the xj in one of the selectrac's 4wd modes without breaking anything, until I get this problem sorted out? The vibration is so bad that it actually has set up another vibration on some part of the dashboard's plastic pieces.

I'd really appreciate info about disconnecting the rear d/s soon so the vibes don't grenade any other part of the drive train.

Thanks!

Mike in NY

it could be possible that the springs have started to sag...throwing off the pinion angle... also check to see if the shim is still siting in the right place...
check the angles before you do anything else
and check all the u-joints front and rear
as far as driving with out the rear shaft...i don't see why it would hurt...especially for a test drive