changing drive shaft on lower unit.

[carlosy2k1]

Hi every one i was wondering if any one can help me here with this issue im having.i have a 89 125 force outboard and my lower unit crack over the winter so I found one locally but it's long shaft mines is short shaft any way to covert it at the lower unit and how?greatly appreciate any help thanks.

 

[Frank Acampora]

I think 1989 lower units were all two piece but I am not certain. Some may have been one piece drive shafts. so:

Yes, If it is the one piece drive shaft it can be converted BUT----- It requires complete disassembly of the lower unit(s) and you MUST re-shim the gears to insure proper gear backlash. Failure to do so will result in shortened service life. Depending upon the severity of incorrect backlash this could range from years to minutes.

You are way better to wait for a complete lower unit and buy that OR if the crack is not too severe, have it welded by a competent welder.

If it is a two piece drive shaft with a coupler, simply swap your short drive shaft onto the lower unit. Then sell the longer drive shaft on ebay.

 

[carlosy2k1]

Yes the original lower unit is two piece shaft with coupler.so how do I change that shaft out I mean remove it.

 

[Frank Acampora]

Two piece is about as easy as you can get. Simply slide out from the coupler the longer shaft and slide in your original. The coupler is splined and the shaft has a small tab on the bottom but it is foolproof--- will take all of 10 seconds.

 

[carlosy2k1]

No Title

Not getting what your saying I could have mistaken what you ment 2 piece shaft,I'm putting pics up of the 2 lower the short shaft I already remove water pump.

 

[carlosy2k1]

So I can't swap all internals from one to the other then?

 

[Frank Acampora]

First photo is a one piece drive shaft. Second photo is a two piece drive shaft. The internal components are completely different. You can not swap one into the other

 

[carlosy2k1]

Well that's not good, so can I still use that lower unit changing it thru the top the guy I bought from still has all the parts from original motor?

 

[Frank Acampora]

The lower unit will bolt to your engine. Then you need to find a coupler and 20 inch drive shaft. (I say 20 inch because that is what your engine is). The actual shaft length is more like 14-15 inches..

When you say the guy has all the original parts, does he have the water pump and lower mounting plate? I don't see them in the photo. These parts are expensive to buy new and usually difficult to find used.



Just to correct your terminology: Force no longer makes short shaft engines in larger horsepower. They would only be found in engines such as 9.9, 15, and maybe as high as 25 horsepower. The length refers to the transom size the engine is designed to fit, not the actual engine leg length.

A short shaft engine is about 15 inches from clamps to anti-ventilation plate. A LONG SHAFT engine (yours) is 20 inches. An EXTRA LONG engine is 25 inches.

 

[jerryjerry05]

IF??? You break the lower unit apart.
You will need to shim if you install any new parts.
Try to find the shaft like Frank suggested or get another lower with the right shaft.
They're out there.

 

[carlosy2k1]

I think theirs a confusion,the lower unit that got damage is the 2 piece which was on my boat and the one piece shaft is the one I bought.the guy I bought the one piece shaft lower unit still has the motor it came off so my question is can I convert mines to the one piece shaft from lower unit to top being that he has part avaliable?sorry for any confusion

 

[carlosy2k1]

Also would it matter changing to the long shaft on a 18ft bayliner capri open bow or I shouldn't do it?

 

[carlosy2k1]

???

 

[Frank Acampora]

Unless the Bayliner has a 25 inch transom OR unless you want to raise the transom 5 inches it is not a good idea. The prop will be sitting too deep in the water leading to handling issues. It will also cause higher exhaust backpressure reducing horsepower and lastly there will be extra drag from having the extra 5 inches of engine in the water. SO: If the Bayliner has a 20 inch transom stay with a 20 inch long shaft engine.