Main Shaft Seal

Q: My husband has a 1979 Harley custom chopper w/ a 80 in shovel an 4 speed trans. He’s having problems with the trans. leaking grease on the drive side. The main shaft seal was replaced, was good for a couple weeks then started leaking again. Any ideas?
Anita B via Facebook

A: The bushing that supports the main shaft is probably worn; allowing the main shaft to have excessive runout. New seals will not stop your trans from leaking. The trans will need to be torn down and rebuilt.

Check out our Trans Project Videos:
Trans Project
  • (will not be published)

5 Responses to “Main Shaft Seal”
  1. Robert

    I have a 2004 H-D Softail FXSTI my speedometer went out I thought so I got one from the dealer installed it and my speedometer is still going all the way up after started. So do I have a bad sensor or am I over looking a fuse some where? Thank You, Robert Coy

  2. Ed

    It is common on a 4 spd transmission for the mainshaft to be worn .002-.004″ where the main drive gear bushing rides on it so when over hauling a 4 spd trans we usually end up replacing the mainshaft as well as the bushing or you will be back in there shortly