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February 01, 2004
My take on it is this...
The prop shaft as a unit, complete with the assembled UJ, does need to be in balance. I believe that they are balanced at the factory, but I don't know to what level of accuracy.
I don't think that they are balanced as a unit assembled to the back axle, which is why I contend that the flange joint betwen UJ and axle pinion can be undone and re-assembled without need to mark it. If the prop shaft is balance as a seperate item then it will remain so in either of the two possible assembly positions. As it can only go together in two positions, at the very worst if it did cause a balance problem it would very easily be corrected.
However, the shaft can most definately go out of balance and this will cause a severe vibration that it is hard to ignore. The commonest cause is worn UJ bearing caps. Presumably the balance weights on the shaft might also drop off.
When UJ bearing caps are replaced then the yolk ends DO need to be marked so that they are re-assembled in the same relative positions. This IS a case when the original ballance of the unit can be altered by wrong re-assembly, so it is worth marking before you start. If you are altering the unit in any way - perhaps shortening for a 5-speeder or marrying in a different UJ to match a Datsun 'box, then the likelehood is that it will need to be balanced, although you may be lucky and get away with it.
Guy
"Guy Weller" < Guy.Weller@... > 28875
Posted on February 1, 2004 06:20 PM
Posted to category(s) Drive Train | Engine (internal) | Exterior | Miscellaneous | Restoration | Transmission
