1978 Mercury 500 50HP Drive shaft Spline issue.

[Ryan1776]

Hello everyone.
Hopefully an easy/quick question.
I'm helping a friend rebuild this outboard and it needed a new drive shaft.
He ordered the correct vintage shaft in length and spline count.
2 issues however.
1-The taper bearing is too small, and the shafts' bearing face is different too. Old shaft has a 1" bearing surface (Bearing ID), new shaft has a 0.900" bearing surface (bearing ID). Which also means the bearing face on the new shaft is much too small as well.

2-And more to my question, while the overall length of the shaft is fine, the splines to the engine are different. Old shaft is 2"; new shaft has 1.25" of spline length. Will this be ok?
We won't want to dry build the whole thing to find out if it fits or not.

Thank very much!
Ryan

 

[Mercurylips]

Ryan1776- I have the correct era motor so I need the serial number off your motor to determine that it is in fact a 78. Also if you have a part # of the "new" shaft, that would help, also. I have a lower unit that has a good shaft in it that I used for a parts donor for my 500. I'll be able to help if I can get the information I asked.

MOD EDIT - PM's only please. Gotta keep the bosses happy.

 

[Faztbullet]

Sounds like he got one for non preload roller bearing ........his should have the tapered cone bearing.

 

[Mercurylips]

Sounds like he got one for non preload roller bearing ........his should have the tapered cone bearing.

I'm glad you know that but I know nothing without part numbers.:joyous: Mike