How to intall a rear crankshaft seal (flywheel side) on a manual transmission Classic 900 without special tool 83 92 540.
While servicing the clutch on my '85 900 8v, I discovered a badly worn flywheel bearing and chose to replace the inexpensive rear crankshaft seal while I had the flywheel out. The book (Bentley) recommends prying out the old one with a screwdriver and installing the new one with a special tool or "suitable seal driver". In lieu of the special tool I read that it can be gently tapped in with a hammer. I don't own any "suitable seal drivers" and I had little success with the hammer-- when I would seat one side the other would pop out, and there is very little space to swing a hammer in the first place.
I resolved the issue by oiling the new seal, then lining it up by hand. Be sure the little spring is facing the engine and you're pressing against the flat rubber side of the seal. I then ran seven 10mm-1.5 bolts with 3/8" fender washers into the flywheel mounting holes. I used the shortest bolts I could find (16mm) rather than the long flywheel bolts so that they wouldn't bottom out. Run them in with a 17mm socket, alternating back and forth keeping the pressure as even as possible as you work the seal into place with the washers. The result will be a fully seated, undamaged crankshaft seal. The attached photo shows the method in action.