15hp 4 stroke lower unit changing

[bowshark]

I got a good deal on a 15hp 4stroke but I didn’t notice it was a very long shaft for a sailboat. What is required to change out lower unit to a 20” shaft?

 

[Bobbywolf]

The biggest issue is the driveshaft length. The water pump tube, and gearshift linkage can be shortened without too much effort, but you really need to buy the correct driveshaft. I have a friend who cut his driveshaft down to length and resplined it, but he also works at a machine shop.

If you found a parts motor with the top end blown up, you could just swap the bottom end over directly and it'll work. This is your best bet.

 

[racerone]

Is there a spacer on the exhaust housing or is it 1 piece ?

 

[bowshark]

Thanks for both replies. There is a spacer on the housing.

 

[bowshark]

The biggest issue is the driveshaft length. The water pump tube, and gearshift linkage can be shortened without too much effort, but you really need to buy the correct driveshaft. I have a friend who cut his driveshaft down to length and resplined it, but he also works at a machine shop.

If you found a parts motor with the top end blown up, you could just swap the bottom end over directly and it'll work. This is your best bet.

That was my intent but wondered about shift linkage and water tube if they had to be replaced or could be cut. Drive shaft would be on the new unit so that Wong be a problem.

 

[Bobbywolf]

Do you know the year of it? Tohatsu had a couple different ways of doing the shift linkage. You can likely cut off 5" from the bottom rod and rethread remainder. However a used bottom end should have the shift rod with it though since it is pinned into the gearcase. The water tube can just be cut to length.

 

[bowshark]

Is there a spacer on the exhaust housing or is it 1 piece ?

I didn’t want to pull it apart and see what was in the spacer part of housing till I got replies on here. I wondered if that spacer included spacers to drive shaft, linkage and water tube?

Do you know the year of it? Tohatsu had a couple different ways of doing the shift linkage. You can likely cut off 5" from the bottom rod and rethread remainder. However a used bottom end should have the shift rod with it though since it is pinned into the gearcase. The water tube can just be cut to length.

sorry I should have posted: it’s a 2000 Honda 15hp, 4stroke

 

[Bobbywolf]

Woa, I thought I for sure read that you said tohatsu somewhere, lol. My mind playing tricks on me I guess. The same advise applies. You can see the differences if you bring up a outboard parts website. I'd post a link, but I'm not sure on the rules of doing such a thing because iboats sells stuff too, albeit aftermarket.

That year honda 15 had 3 different length lower shift rods, driveshafts, and water tubes. If your honda is anything like the 25 I'm working on, the water tube is just a straight tube where it enters the waterpump, and would be easy to cut shorter.

 

[bowshark]

Woa, I thought I for sure read that you said tohatsu somewhere, lol. My mind playing tricks on me I guess. The same advise applies. You can see the differences if you bring up a outboard parts website. I'd post a link, but I'm not sure on the rules of doing such a thing because iboats sells stuff too, albeit aftermarket.

That year honda 15 had 3 different length lower shift rods, driveshafts, and water tubes. If your honda is anything like the 25 I'm working on, the water tube is just a straight tube where it enters the waterpump, and would be easy to cut shorter.

It has a spacer housing that I was hoping could also be spacers inside that all could be removed? Just trying to find out more before I mess with anything. If I get responses that say it’s a bad idea then I’d proceed to other options. Thanks for your reply.

 

[bowshark]

Is there a spacer on the exhaust housing or is it 1 piece ?

 

[bowshark]

This is what I’m calling the spacer? Not sure if that’s what you mean?

 

[Bobbywolf]

Just to clarify, that housing spacer is just that. A spacer. It would need to be removed to shorten the outboard.

Inside that are 3 parts that require the shorter version. The driveshaft, water tube, and shift link. These would need to be replaced/modified to complete the job. There are no extra sections of these there to make them shorter. You need the shorter versions.

I hope this helps. Digging up an 8 year old thread doesn't help you, (and is against forum rules), so I wanted to post here to clarify.

 

[racerone]

The gearcase would need to come apart to change out the driveshaft.----And step #1 is to check availability of parts.

 

[bowshark]

Just to clarify, that housing spacer is just that. A spacer. It would need to be removed to shorten the outboard.

Inside that are 3 parts that require the shorter version. The driveshaft, water tube, and shift link. These would need to be replaced/modified to complete the job. There are no extra sections of these there to make them shorter. You need the shorter versions.

I hope this helps. Digging up an 8 year old thread doesn't help you, (and is against forum rules), so I wanted to post here to clarify.

Sorry I didn’t dig up anything. I googled my problem and it led me to the same question I had asked on here so I replied to what google sent me to. Sorry to have bothered anyone and thanks for the answer to my situation.