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View Full Version : Prop aligment - how accurate is yours?


jps
11th December 2013, 03:13 PM
I tacked up some engine mounts last week (although one weld subsequently snapped - so I am back to square one) but before it broke I did the following...

1.Mounted the diff.
2. Chopped a piece of wood to act as a dummy prop shaft
3. Used a t square to mark off the angle the prop 'should' have followed if it were perfectly aligned from the diff input flange and the gearbox output flange
4. Compared to the actual centreline that the 'dummy prop' was following

Without a super sharp pencil - and trying to hold 3 things at once - it looked as though the alignment was out at both ends - and in both the vertical and horizontal planes.

Horizontally - i.e. left to right in the car - it was roughly 3 degrees at each end - the gearbox effectively pointing more towards the o/s side rear wheel than it was towards the diff - by my calculation the prop would be about 20mm off centre at one end if it were a rigid tube.

Vertically - i.e. up and down in the car - it was roughly 2 degrees out at each end.

The diff input flange is vertically square - as is the gearbox output shaft - as far as I can tell.

How does this compare to anyone elses setup? I know the uj's are there to take out this discrepancy - but I want to be starting from the right ballpark...

K4KEV
11th December 2013, 04:35 PM
It has been quoted once or twice before that a perfectly aligned prop will actually wear out faster so a couple of degrees here and there will be of benefit and the uj's will do the job of taking up any misalignment you have so go go go dude:D :D :D

baz-r
11th December 2013, 08:52 PM
D&F say you need to have some off set to stop the uj needle bearings grooving up.
ideally you would have the engine front pully and box output on your center line and make sure you have a bit of a hight difference between the diff and box output the actual amount you need is dependent on prop length but iirc 3deg is the minimum angle for uj's
ask dunning and fairbank along with a quote for a new prop but I would be surprised if you can get a new one anywhere near what they charge