Is it difficult to rebuild a lower end?

[Saskatoon2005]

I was curious if it was difficult to actually rebuild a lower end? I see so many people buying a used lower end to swap their broken one. Why wouldn't they just rebuild it and then they know what they are getting and that it is brand new! I have a 1969 40 H.P. Johnson Sea Horse, and it runs great. I was just curious.

 

[jwbmarine]

Re: Is it difficult to rebuild a lower end?

Your's is not too bad,..but the larger the engine,the more complex they get,and more specialized tools are needed.It becomes a longevity issue,getting it going,and getting it going properly,become 2 diff things.

 

[Saskatoon2005]

Re: Is it difficult to rebuild a lower end?

I see thanks for the input....

 

[Walker]

Re: Is it difficult to rebuild a lower end?

One reason so many people opt for used LU's is repair costs can easily be double what you can get a used one for.

 

[mikesea]

Re: Is it difficult to rebuild a lower end?

A gear set for your engine would cost more than it's worth.Most times the gear that goes is the "dog gear"it's purpose is to do the shifting from forward to reverse.But if the forward or reverse gear wears out,it gets costly,The forward gear is made of heavier material due to its mostly used.Ive heard that reverse gears can be swapped but they wear quicker.I also worked for a guy that took a dremal tool and repaired the parts of the gears that mesh together,the 'dog gear and forward gear,actually worked.

 

[rodbolt]

Re: Is it difficult to rebuild a lower end?

beats me, OMC/BRP gearcases since the 80's are the easist cases ever to rebuild as most only require shimming of the pinion gear. shimming the pinion is usually a 5 min operation. in fact it takes me longer to find my feeler guages than to actually shim one.
last one I did cost 390 dollars for a gear set and seal kit and took just under 3 hours.
if ya really want to amuse yourself the replace the gear set and prop shaft on a V6 suzuki .

 

[Saskatoon2005]

Re: Is it difficult to rebuild a lower end?

Cool, but I have a 1960 Johnson 40 Hp. If it ever went, I was wondering if I could just do the work, myself...3 hours seems like a long time. I mean, remove lower end, put on a bench unside down, remove split lower end, and everything is right there...remove replace and put back in. 3 hours? Wow, I guess i must be missing something....

 

[Scaaty]

Re: Is it difficult to rebuild a lower end?

...remove replace and put back in. 3 hours? Wow, I guess i must be missing something....

Y[colour=null]ep, 30 or 40 years of expierence doing it.. [/colour] 8)

 

[Saskatoon2005]

Re: Is it difficult to rebuild a lower end?

I would love to get an in depth lesson on the removing and replacing of gears for the lower end...something that everybody is afraid to do is worth learning, because there is definately a market for it...

Thanks again...

 

[itstippy]

Re: Is it difficult to rebuild a lower end?

1960's era Bigtwin mechanical lower units are simple. You want a manual though to help keep things straight. Follow the manual and take your time and if you're reasonably apt you will have no problems. I have disassembled them entirely, cleaned everything, put in new seal kits, and put them back together without any formal training just by following the manual and occaisionally posting for help on this forum. It would have been no problem to install new parts if they were needed.
Mikesea hit it on the head. Cost and availability of parts. Why chase around trying to locate NOS NLA parts when eBay and the boneyards are overflowing with 1960's era Bigtwins? A hundred bucks gets you a Bigtwin with a blown powerhead. Use the good lower. A hundred bucks gets you a Bigtwin with a disfunctional (usually Selectric) lower. Use the powerhead. The only new parts anyone orders for those old Bigtwins are consumables like impellers, coils, and seal kits. Evrything else is readily available used and cheap.

PS: I am SLOW. To disassemble, clean, inspect, and reassemble a Bigtwin lower with a new seal kit takes me closer to three days than three hours. I stop and look in the manual and post on this forum and have a beer and . . . But I enjoy doing it. Rodbolt can do it in three hours and when he's done everything is absolutley tiptop. Rodbolt is a very experienced pro who fixes OMC products for a living. His shop time is worth about $100 an hour. Most folks wouldn't bring him a 1960's Bigtwin to work on.

 

[BF]

Re: Is it difficult to rebuild a lower end?

If you think 3 hours to redo a lower unit seems like a long time, then you definately should find yourself a project one to take apart for fun.

3 or 4 years ago I rebuilt the lower unit on my V6 merc myself when it broke the driveshaft... I have a difficult time imagining how many hours it took me to get it done. (having to fabricate special tools along the way, run all over the place for bearings and other parts). It took me hours just to figure out how to get the pinion nut off. Probably something like 30 to 40 hours (?) in total... Mind you that included a lot of beer swiggin' head scratchin' time. It was my ongoing spring project that year. But gratifying in the end.... and still going strong. It would've cost me about $2K (maybe a bit more) to have it done... parts cost me ~$600. I decided to tuck into it because I figured I had nothing to lose.

 

[rodbolt]

Re: Is it difficult to rebuild a lower end?

I have done more big twin forties and ski twin 33's than I care to remember.
my uncle had 3 beach launch dory's with 2 big twins for each for about 10 years.
I wont touch one today as they are not worth the shop time in this area due to the salt corrosion.
however I am paid by the hour and have been mostly a 1 or 2 man shop for years and years so I tend to hustle.
you do 20-50 of them and its easy until the salt monsters grab you.
I am not paid commision but I do try to beat the flat rate manual just to see if I can.
especially if its a warrenty deal .
I know it sounds like sacrilidge but we cut V notches in the aft cowl so we could access the aft lower unit bolt without removing the cowl.
I cant remember how many 1/4x20 phillips headed screws there is but we could break about 1/2 of them every time.
biggest issue we had with big twins was motor mounts and the lack of replacements by the mid 90's.