800 stringer upper gear case swap

beaudeen · Jul 31, 2005

I have a 1981 Caravelle 305 gm 185 hp 800 stringer 1:1.50 drive..kids took boat out before i had a chance to fill gear oil...upper is shot..found a relacement(used) that seems to be in ok shape,but it is 1:1.25 drive...looks like it will bolt right on, but will it work..?? your thoughts would be greatly appreciated..only have 6 weeks of boating left in our season

KaGee · Aug 1, 2005

Re: 800 stringer upper gear case swap

It will work, but you will have to watch your revs. The lower gear ratios are all the same in that series. Ever think of hiding the boat keys??

beaudeen · Aug 2, 2005

Re: 800 stringer upper gear case swap

Thanks for the input...I know this is not a good way of correcting my situation, but economics prevail...could I compensate the higher REV's with a coarser pitch prop..or just leave the setup alone and keep an eye on the rev's...I pull alot of skiers..what will I be giving up on the low end and what would I gain on the high end..??...thanks again for your input..

KaGee · Aug 2, 2005

Re: 800 stringer upper gear case swap

Yea, you may be able to play with the prop. I'm not well versed on that subject and it may be best to post that question later in the "boats, not engine" section. I'd play it by ear until you see what you have.

whywhyzed · Aug 3, 2005

Re: 800 stringer upper gear case swap

those aren't ratios that OMC ever used on 800's .. who's telling you these ratios? You can get a rough idea of ratio by turning the drive and counting input turns vs. output turns.

WSUDERMAN · Aug 3, 2005

Re: 800 stringer upper gear case swap

If you are only swaping the upper gear case, then you would need to look at that ratio only, not the final drive ratio. The ratios for the upper gear case for the 800 & 400 are as follows... 800 ratio year models 21:16 1978-85 260 hp 5.7l v8 21:17 1978-85 185-230 hp 5.0l v8 21:19 1985 4.3l v6 21:20 1981-85 170-180 hp 3.8 v6 400 21:18 1978-85 120-140 hp 2.5/3.0l the 21:17 ratio translates to 1:1.235294 the 21:16 ratio translates to 1:1.3125 not much difference but it will change the final drive ratio. if I installed a 5.7l 21:16 upper on my 5.0 the final drive ratio would go from 1.516 to 1.566.

beaudeen · Aug 4, 2005

Re: 800 stringer upper gear case swap

Well I spoke with the guy that is selling the unit..all gears look good and the ball drive looks new..he says it is a 1:1.25 drive...have never heard of that drive before, he said it was off of a V8, so i'll just swap it for mine and see what happens..i'm sure it's close enough..just waiting on a manual before i tear it apart..any tricks i should know about from you experienced people..??

steve n carol · Aug 4, 2005

Re: 800 stringer upper gear case swap

beaueeen, I don't know anymore about the 'stringer' drive, than what I have read on this site, and there is alot here. Seems that they are kinda rare and that parts are expensive. And I have read threads that discuss users problems with filling the drive with oil, (type and locations of filling). I remember reading that the oil locations were found after damage was done...I am sure others will respond to your question, use the 'search' option for this topic, as there is lots if info for the stringer out drive...sl P.S. BTW, what did you have to give for the used out drive? and welcome to IBoats.

whywhyzed · Aug 4, 2005

Re: 800 stringer upper gear case swap

if both are V8 uppers, you will prob be ok - just watch the rpm's - you might have to change prop pitch to keep your engine in the correct wot rpm range (4200 - 4600).

KaGee · Aug 4, 2005

Re: 800 stringer upper gear case swap

Hey Beau... Just my ..02 worth... You should consider a new water pump impeller while you are down there. I'd buy the kit. You probably want to buy new gaskets and seals for the trunion caps. It's good to have an extra hand on board to push out the shift cable while you pull on it. Careful with it... they are $$ if you kink it. If you haven't changed the oil in the intermdiate... good time to do it with the drive off.

beaudeen · Aug 5, 2005

Re: 800 stringer upper gear case swap

Hey guys...thanks for all the input...picked up the upper gearbox for $200 including shipping from Vermont area..sounded reasonable to me..my 18 year old son is giving me a hand as him and his friends are the ones that caused the problem..a learning experience i guess..FYI.....glm-marine.com has all parts for stringer out drives if anyone is in need..downloaded their parts breakdown of the complete stern drive..hope to get the beast back in the water as the summer is nearing the end..thanks again for all the info..!!!

KaGee · Aug 5, 2005

Re: 800 stringer upper gear case swap

No problem.... Good Luck!

beaudeen · Aug 5, 2005

Re: 800 stringer upper gear case swap

Hey...probably 2 weeks before i get a manual..I'm a military prop guy C13o...these stringer drives can't be that complicated..???How do I remove the beast from the boot without screwing things up...??..from what I've read, the only concern is the shift cable..I'l fix it and dump it..funny..You don't know what you have untill you've read the posts...merc outdrive...here we come...it's a good boat though..that is untill you read..!!!

greentahoe · Aug 7, 2005

Re: 800 stringer upper gear case swap

As far as the shift cable goes, make sure to disconnect the battery ground cable before touching the shift cable. The steel cable itself is pretty small, and if it should somehow get in contact with a hot wire it could very quickly get burned off. This is advice I got from my friendly OMC dealer. The last time I checked that shift cable was around $250.00, but that was 5 years ago. Good luck.

800 stringer upper gear case swap

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