I'm up to reassembling the diff.New planet gears, comp diff pin, washers, bearings.Spins nicely until I tighten up the crown wheel to the cage to specs.Then it doesn't move.
I take it thats not right and my new washers are a bit too thick.I'm using brass washers instead of the fibre ones.So go back to fibre or can I thin out the brass ones or is there something else.?

Thin fibre ones out of an early MK1 diff is the way to go

My bad It is the thin brass ones out of an early MK1 - I had to use them as the new fibre ones were way too thick - lucky I had an old MK1 diff here and I pulled them out and used them

_________________
David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

Brass ones are better than fibre. They don't fall apart with dirty oil.
The fibre washers they sell now are too thick and by your problem new brass ones are too.
One way to use them is get a few thou surface ground off the centre hexagonal spacer.
Last diff I did needed .008" off (.004" off each side). You just grind 2 opposite faces, put these towards the side gears.

<edit> you need to do a trial assemble with 1 washer missing, then use feeler gauges to measure to the spacer see what the remaining gap is.
Then compare that to spacer thickness.
You only want about .003"-.005" total clearance.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.