getting ####ed off at shuddering/vibratin in in steering wheel!!!!

Get a wheel alignment and balance?

 

the car lowered? if so and youve covered the balnce/alignment thing, then youve got the same problem as me: driveline phasing.

DRIVE LINE PHASING

 

Harmonic balancer maybe or a long shot at warped rotors.

 

Center bearing and Unis?

 

I seem to remember reading somewhere that when you lower a car with a 2 piece prop shaft, you should also alter the position of the centre bearing so as to return the prop shaft line to that it was before lowering. I know on Jaguars with the 2 piece tailshaft, you make tool (simply 1.5m of 3X2 with 4 large nails embedded) that you hold against the prop shafts and then raise/lower the centre bearing so the shafts are in a straight line. I also know that with Jags this adjustment is not always critical with some cars needing it and others that don't need adjusting. The fact that yours has had a side impact may have made this more critical. It's simple to do and requires only a length of 3X2 and 4 nails OR you possibly could use a length of cord streched tightly from the gearbox to the diff and then take measurements off that.

 

The rear half of the shaft moves up and down as the rear axle moves but it will always return to the same position when the axle stops moving (over bumps)....however if the car is lowered, the normal position is different. As mentioned before, I've seen this subject discussed on this forum with regards to lowering....plus the prang! However, did a quick search and found this which deals with the centre bearing alignment - it's from a Volvo site...they use the same style tailshafts.

Before you conclude this is the problem, make sure your engine and transmission mounts are in good shape. The level of driveshaft vibration can be reduced by changing the vertical position of the center support bearing. The support bearing is bolted to a bracket, which in turn is bolted to the underside of the car body. Adding shims or washers between the car body floor and bracket will shift the bearing down. Adding shims inside the bracket between the bracket and support bearing will shift the bearing up. Best results differ from car to car. Start with a change of 6mm (1/4") upwards. If results are not acceptable, try positions from 5mm (3/16") downwards to 12mm (1/2") upwards from the original position. Note that clearance between drive shaft and fuel lines must be at least 20mm, and between drive shaft and the fuel tank at least 16mm. Shimming upwards should not exceed 12mm (1/2") and after re-positioning the center support bearing housing should not contact the floor pan.

The site is: Driveshaft, Rear AxleDriveline, Rear Axle

I'll also see if I can dig up the stuff on my old Jaguar.

 

Are you running stock brakes? Has it got aftermarked wheels? Have you got shims in the wheel spiggot bores?

 

Found some info which should make sense from JagLovers archives:
When I first bought my 77 XJ12L back in '85 it had this strange shudder in the driveline, (or 'judder' as the Haynes manual calls it), whichmeant that the two part driveshaft with a centre support bearing was
mis-aligned. It is adjusted by sliding the centre support bearing side to side. According to Haynes there is a 'special tool' for aligning driveshafts in series 1 and 2 Jags which looks prepostrous and of course,
un-obtainable. My (very good) Jag specialist mechanic had never heard of this tool and tried to align the shafts by trial and error... up on the hoist, loosen the four bolts and their rubber mounting washers, move
the bearing and its bracket, road test, then back on the hoist again...to no avail. In desperation, I went to a (Gulp!) Jaguar Dealer who talked me into replacing a perfectly seviceable centre bearing and
new rubber washers on the bearing mounting bracket, assuming he would align the shaft as a matter of course,(given the high hourly rate he charged and all that plush carpeting in his waiting room,) but it STILL
shuddered on take off...although it was smooth as silk at any higher speed. So one day while I was replacing the rear transmission coil spring,I used my own brain instead of Haynes's or the Dealer's or the Jag
specialist's and came up with this solution: Take a four foot carpenter's level (as straight and rigid as you will get), and 4 six inch lengths of 3/4" wood dowel, duct-taped to the level at four places, the spacing of which correspond to each end of the two driveshaft tubes. Insert this 'gauge' up into the holes in the driveline shield so that the sides of all four dowels just touch the sides of the driveshaft tubes, or move the bearing until they do, and you are aligned, at least laterally. The vertical alignment seem to be set at the factory, thus the importance of new rubber washers and the transmission rear mount coil spring.
Smooth as silk ever since...as a Jaguar should be.

 

Check the c angle at the diff nose and tail shaft alignemnt side to side do you have an adjustable panhard rod ? the centre bearing support bracket should have the spacers between the bracket and the bearing collar not the bracket and the body which will raise the tail shaft up to bring it into aligment with the lowered suspenion