Logo
FULL SITE MENU

Replacing lower unit. How to ensure donor is compatible?

D

djcamera

Contributing Member
Shopping for a used lower unit for my 1986 Mercury 75hp 2-stroke. Many ads say a unit is good for multiple horsepowers. Is there a resource that will help me make sure a used one will fit? Thanks.
 
Carefully look up the components (gaskets, shifter rod, etc.) for your motor (per serial #) and the LU you're looking at. Make a list of the part numbers for each part (using this site) and compare.

In general, your motor uses the large, 8 spline tower and gearbox of the in-line sixes, so there's a lot of them out there.

Jeff
 
Ensure its a 2:3.1 gear ratio...80/800/85/850/75 hp engines from 1975 -1987 will fit. Yours has the swept skeg and older ones have the straight skeg.
 
faztbullet said:
Ensure its a 2:3.1 gear ratio...80/800/85/850/75 hp engines from 1975 -1987 will fit. Yours has the swept skeg and older ones have the straight skeg.
Click to expand...

You're right about the skegs. One I looked at yesterday (70hp made in 1983) had the straight skeg, while mine is swept. So they don't have to be identical? Interesting.
 
Back
Top