Will this LU fit Force 1984 125 hp?

[labawg]

Supposedly this LU came from a 1983 Force 125 hp. It has the two piece shaft and looks much later. By looking can anyone tell me is it will fit and does it have an 2:1 gear ratio?

 

[lucas_chrysler_1]

Re: Will this LU fit Force 1984 125 hp?

no it did not come off of a 1983 force 125. mostly because A. in 1983 force was still chrysler, and B. it is black with the 2 piece drive shaft. so you are right to think it is off of a later motor. it will fit you motor BUT they did change water pump housings through the years (once) so you might have to grind a little piece out of you lower leg (not a big deal, you can even breake out a chunk with a pair of pliers and a hammar) and as for the gear ratio, looking down from the top of the lower unit you will see 2 numbers 1 saying forward gear, and i forget what the other number says, but that will tell you your gear ratio. or turn the shaft by hand and count the ratio. but this Will fit your motor. just be sure the shaft length is the same.also it apeers to be missinf the exhaust snout

 

[Frank Acampora]

Re: Will this LU fit Force 1984 125 hp?

It is a 1990-1994 lower unit, dual exhaust, I think Type "C" because of anode placement. (They made 4 different versions of the lower in those years.)

It has a Mercury style water pump, plastic with a stainless insert cup.

It is probably a 1.92 to 1 ratio.

It will fit on your engine with little to no modifications. Your exhaust snout will fit it.

I can't tell for sure from the photo, but if the driveshaft is 19 inches long (which it appears to be) it is for a 20 inch long shaft engine. If it is 24 inches, it is for a 25 inch extra long engine.

 

[labawg]

Re: Will this LU fit Force 1984 125 hp?

I currently run a 17 pitch prop(5200 rpm WOT), If it 1.92:1 would I go to 19 pitch to start or something less?

 

[Frank Acampora]

Re: Will this LU fit Force 1984 125 hp?

Start with what you have--if it is a through hub exhaust prop. See where the engine RPM are and go from there. If you are currently running a 1.76 to1 lower and need to buy a prop, then try a 19 pitch.

My experience on my hull with this unit is that it is just about equal in performance to the single exhaust lower. However, it does tend to ventilate easier than the single exhaust. Hole shots need to be done with trim tucked in. Once the boat is on plane and the prop has locked-up I can then use full up trim again. It will ventilate in turns though so I need to trim down on them. This lower unit NEEDS a prop with a sizeable flare ring at the exhaust to run properly.

Personally, although there is nothing wrong with it and it does have a better water pump, I don't really care for this lower unit design. I bought mine so I could find out how they were different and what was needed to repair them. Having done a good bit of testing with various props, I think I will remove it from the engine and sell it to someone who needs to replace a dual exhaust when they come to me for repairs.

 

[labawg]

Re: Will this LU fit Force 1984 125 hp?

My goal is to find a ~2:1 LU so I change the Performance profile of my motor. I have 1984(tinny) 18' Nordic Crestliner BR with the super deep V. It currently gets to plane in two seconds of a hole shot so it does well, but would like to play with the motor to see what it can really do.