I have a leak from the speedometer drive The assembly has been removed from the gearbox The new square washer appears larger than the hole it fits inside. My question is what has to be done to ensure it fits, have tried just pushing it in with a drift and it simply shears off the excess rubber ( part 65)
scrape a light chamfer on the edge of the hole with a sharp penknife. Try winding some dental floss tightly around it, grease it and push it in. Then unwind the floss. There was probably an install tool with a funnel to compress the seal as the drive was pushed in. Easy enough to make up if you have a lathe. Alternatively, a modern o ring might be the cure. You can get selection boxes of o rings on ebay or from your local plumb center. I had a 1950 sprung hub, iron barreled Thunderbird, back when I was16, mid '60's. Oil leaks were normal then. Rain never soaked through my boots!
Grease the shaft and seal , wrap the shaft in a soft pliable plastic tube (cut old ice-cream tub lid) push in shaft, with plastic wrap hard against the gearbox housing, wriggle the shaft and seal in !
Are you sure the oil leak isn't coming out from the speedo cable itself? Modern cables have the outer part crimped to the end ferrule with no effective seal, so the oil leaks between the ferrule and outer cable. The fix is to seal the join with self-amalgamating tape. It took me a while to figure out that it was the cable and not the speedo drive that was leaking. Worked for me on my Tribsa, but that had a BSA gearbox so yours could well be a different issue.
