1989 Force 125 lower unit driveshaft replacement?

[cich69]

Hello,

I have rebuilt mercury and OMC lower units but never a force lower unit.

I have a 1989 Force 125 lower unit short shaft that has bad gears. I bought a used lower unit from another Force but found out it has a longer driveshaft than mine.

I know I would need a manual to change the driveshafts, but before I buy a manual I want to know if this would be cost effective for me to attempt? Would I need a lot of special tools?

Would I be better off just to buy a used short shaft lower unit and install it?

 

[jerryjerry05]

Re: 1989 Force 125 lower unit driveshaft replacement?

Special tools are needed.Try to sell the one you have and buy another.If you try without the tools you'll be buying again soon.
Buy a factory manual(Clymer/Seloc,not really that good),they list the tools you need to buy$$$$.
Profile??You might be close to someone who can help.J

 

[Frank Acampora]

Re: 1989 Force 125 lower unit driveshaft replacement?

First, you need to know if both are the same year and if both are the same type--that is, single exhaust or dual exhaust and if the gear teeth are cut in the same direction. Around that time, Merc started to play with different gearing.

If the only difference indeed is the shaft length, then you have the option of swapping the gears from the long shaft lower into the 20 inch lower and no other work should be required, Depending upon how well the pinion sits on the taper and splines. You also can swap your drive shaft into the good lower unit, but then you must re-shim the pinion backlash. This does require special tools but can be done by hand.

Take a couple of photos of each lower unit showing full side view and top view of the water pump then come back.

 

[cich69]

Re: 1989 Force 125 lower unit driveshaft replacement?

Thank you for the replies. I don't think I'm going to try this. I will most likely just look for another 20 inch shaft lower unit.

I don't want to spend a lot of money on special tools that I will most likely only use once.

 

[shytownborn]

Re: 1989 Force 125 lower unit driveshaft replacement?

where are you located, i have one