Lowers Unit?

[tompowers85]

I have a 75 mercury 850 that revearse gear stop working, so i purchase a lower unit from a 78 mercury 800. Is the 800 and 850 the same gear type or will this affect my motor? Thanks for any help.

 

[Chris1956]

Re: Lowers Unit?

It should bolt up fine. You need to check the gear ratio. Your 850 had a 2.3::1 ratio. The 800 may have a 2::1 gear ration. If so, you will need a prop with 2" less pitch to run the 800 lower unit.

BTW - They may be the same gear ratio as well....

 

[tompowers85]

Re: Lowers Unit?

How do i find out the gear ratio?

 

[Chris1956]

Re: Lowers Unit?

Only two ways I know. Look it up somewhere or turn the driveshaft and watch the propshaft turn. If it is not 2::1, it will be 2.3::1, so it should be easy...