TOPIC: 1984 115 hp lower unit removal

Hi all,

Its been awhile but I am about to remove the lower unit on a 1984 115hp and shorten it up from a 25 inch to a 21. I am more familiar with OMC's but I have a great 115hp Merc that needs attention. I have a lower unit for parts like drive shaft and water tubes plus the Seloc manual which is vague in spots but I would like to know if there are any tips before I tear into it.

The lower unit will already have s 20" driveshaft and uses a stub shaft on it to obtain the 25" modification.
I have seen a 25" driveshaft in an inline-6, but I believe it was a modified 20".
The unit will also have a unique set of studs, water tube extension, shift shaft extension, and exhaust tube extension that you will be removing.
If you end up with a complete extension kit, it is easy to sell.
I have attached a picture showing how to remove the lower unit.
The picture is of an older unit, but the instructions are the same.
doc Frankenmerc

Oh I like the "how too" sketch tips on a picture. Says it all on one page I honestly have spent hours researching how this is done, if I should give it a try without destroying this sweet 115 Tower of Power Thunderbolt Ignition!!!! It has served me well and now has moved and gets to push a smaller 17ft Larson Sea Lion.

Now how cool would that be to have the modified drive shaft with the extension kit. I'll keep my fingers crossed because it looks to me, how I understand the Seloc manual, (Prefer Clymer)that you have to pull the propeller shaft assembly to remove the drive shaft...Im curious is that true?
more

YEP !

"Now how cool would that be to have the modified drive shaft with the extension kit."

I think you may have misunderstood me.
When I referred to a modified driveshaft I meant that a standard driveshaft may have been modified to 25".
In your case, you don't want to find a modified driveshaft - you want to find an original 20" driveshaft that has the Bay Kit's stub shaft on top of the original 20" driveshaft.
(the Bay Kit is an after-market kit of parts used to make a 20" motor a 25" motor)
doc

Yup looks like the bay kit. You should have a useable lower unit there ready to re install after you remove the extension. You will need a shorter water tube.

a water tube extention was in the bay kit. or cut the long water tube.

Thanks all. I should be attempting get after the lower unit this weekend after I fire it up to make sure all is in order since it has been transferred and sitting for a couple of years. I did get a kit that comes with what looks like all the goodies for the impeller replacement. I will be sure to post a follow up oh how its going if I don't come up with more questions before then.

Dr. Frank... In my excitement to hear I may not have to pull the drive shaft my response was coming from one who still has a lot to learn...like I said I'm an OMC kinda gal and learning something new like MERCURY's intimidates me. Wish me luck and believe me if I get over my head I will get with one of my Merc buddies who has done this before