I just took the top off a 4-speed Shovelhead transmission that I built in 1992. I have no idea how many miles are on the gear set because the bike didn't have a speedometer for about 15 of those years, but I know the bike got three top end overhauls during that time, was flat worn out at the third one, and is now due for a well -earned fourth top end as part of this tear-down. So the transmission has a few miles on it.
The transmission looks new inside. There is no damage, no obvious wear patterns, and even upon the closest inspection no discernible wear that would be a cause for concern or influence the function of the transmission in any way. The gear teeth look great, the shift clutches look great, there is nothing to repair. It's getting a new shifter top gasket and going back together.
So what was the oil? Leftovers from engine oil changes mostly, nothing special. Straight-weight SAE50 in cool weather, SAE60 in hot weather, a shot of 20w-50 if it was cold out, just whatever premium motorcycle oil there was extra of.
I'll defer to the oil experts here, but my guess is the transmission looks new because it leaks as bad as most four-speeds and it was getting a steady supply of clean, new oil. For all the HD riders here who keep saying it doesn't really matter what you use as long as it's good quality and you change it at the right interval, well, it looks like this old bike says you're right.
The transmission looks new inside. There is no damage, no obvious wear patterns, and even upon the closest inspection no discernible wear that would be a cause for concern or influence the function of the transmission in any way. The gear teeth look great, the shift clutches look great, there is nothing to repair. It's getting a new shifter top gasket and going back together.
So what was the oil? Leftovers from engine oil changes mostly, nothing special. Straight-weight SAE50 in cool weather, SAE60 in hot weather, a shot of 20w-50 if it was cold out, just whatever premium motorcycle oil there was extra of.
I'll defer to the oil experts here, but my guess is the transmission looks new because it leaks as bad as most four-speeds and it was getting a steady supply of clean, new oil. For all the HD riders here who keep saying it doesn't really matter what you use as long as it's good quality and you change it at the right interval, well, it looks like this old bike says you're right.