View Full Version : drivetrain alignment

31-12-01, 05:33 PM
As you may know, the jag diff drive plate is slightly offset to the offside. When I install my engine, would it be best for me to angle the drivetrain over a couple of degrees towards the diff or is it best to centralise the eng/box and let the u/j's take care of the difference?

31-12-01, 06:10 PM
I'm no engineer but UJ's cope with the much bigger misalignment in live axle cars, so I doubt whether it is necessay to bother with aligning, also consider the angles they have to cope with in the half shafts with the suspension movement. My advice is don't bother to align the engine and box you may run into other probs.


31-12-01, 07:00 PM
Simon - any "pure" engineer would say the better the alignment, the better the drive. On my old car the engine was angled to meet the diff nose better, on my current car I left the engine straight and let the prop shaft UJ's do their thing. On reflection, I might have moved the engine slightly if I did it again, but not so much as to give me any exhaust system alignment problems. I did try to get the vertical alignment as good as possible though by adjusting the gearbox mounts.
With solidly mounted jag diffs and reasonably solidly mounted engines in our cars, the propshaft UJ's are not overworked anyway. I can't remember the limit of misalignment they are meant to cope with, so use the old rule of thumb - if it looks right.............


01-01-02, 09:26 PM
Hi there Simon I'm sure that if you worked out the actual amount in degrees it would be very small. Obviously the shorter the propshaft the more angular misalignment but this should still add up to less than what is regularly happening with your drive shaft U,J,'s So I don't believe you should have a problem.One thing to look at is the clearance on the u.j. yoke on your propshaft at the maximum deflection providing nothing is touching you should be ok

Paul Gayter
02-01-02, 06:17 PM
Hi Simon,

The operation of a Hardy Spicer U/J as fitted to the propshaft relies upon a small amount of angular deflection in order to keep the rollers in the bearing cups rotating. This ensures the distribution of the grease and eliminates the possibility of the rollers flatting due to non rotation.

So keep your engine on the centre line and let the U/J's do what they do best.

Hope this helps

All the best

Paul Gayter