Looking for some help. I had the reverse box out of my Stuart Taylor Blade so I could dismantle it and check its internals, seemed all good so put it back in but noticed that the rear propshaft Uni's were 90 degrees out of phase. I have been told that they need to be in phase so have changed the yoke, there is now a slight vibration at higher speeds which I imagine would be due to the fact it needs to be rebalanced again which I intend to get done but my question is, why would it have been balanced with the Uni's 90 degrees out of phase in the first place? There was even a line up mark on the shaft and the yoke so if they were removed they could be lined back up again....out of phase. Any ideas? I don't want to get the shaft rebalanced with the Uni's in phase if it turns out there was a reason for them being set up out of phase.

The yokes on any one prop shaft should be in line with each other, so if the sliding joint was pulled apart then you need to put it back in line. The in balance may have been caused because it was but back 180 from what it was originally.....

UJ yokes must always be on the same line (phase).
Also propshafts get a 'set' over time (due to torque) and should be marked when removed, and refitted in the same position.

I was confused about this, so I rang Bailey Morris. It appears that the shaft with the centre bearing attached is
built out of phase. If this is the case with yours, and you have put them back in phase, that could be your problem,especially
if it was ok before.
If you download the Kit Car two piece prop PDF from Bailey Morris
you can see the different configuration.

It doesn't matter whether it has a centre bearing or not, they must still be in line. Having been in the commercial vehicle trade for a long time I could relate some real horror stories about yokes not being lined up correctly, particularly on long vehicles with chassis extensions....

I can see why 45° out would be a problem, but surely 90° wouldn't, as the axes of the pivot points would still be in line and with the very limited angles allowable for UJs, any differing movements between the ends in a particular plane as the shaft rotated would be tiny?

Thanks guys, I think I will keep them in phase and get the prop rebalanced.