Im changin the pinion seal on the propshaft part of my cortina diff. How do I undue it as I had to laugh when I started undoing it i realised all i was actually doing was powering myself across the garage. Does it undue anticlockwise????? and how do i stop moving the car (other than putting it up on stands?)

I take it you mean the central nut on the diff flange where it attaches to the prop?? I would refit two old propshaft bolts and use these to stop the flange turning using a solid bar (ie trolley jack handle etc) while you undo the nut. You could also drill a couple of holes in a steel bar and stop the diff turning that way

I held the flange in a HUGE vice that i have on my bench.

Edited to add...not really going to work if the axle is still in your car

As above, couple of bolts and a steel bar should do it.

[Edited on 23/11/10 by tul214]

What are you going to do about ther crush washer? You can very carefully count and mark up to give you the exact number of turns to remove the nut, but be aware it really need a new one and proper setting up... FYI I found the pinion oil seal a PITA to change - Ieffectively had to cut the old one out, as their was a ridge in the metal holding the seal in place... Not much fun!

I locked the wheels with my handbrake - and chocks either side of the wheels.