Rebuild Alpha One, Change Gear Ratio?

greg82255

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Hello,

Is it possible to change the gears in a 1986 Alpha One and convert it from 1.5 ratio to a 1.32? I've been researching and can't seem to find a definite answer. If it's possible, where could I find the parts, and how much time and $ am I looking at to do this? Thanks in advance
 

Bondo

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Re: Rebuild Alpha One, Change Gear Ratio?

Ayuh,.... It's Possible, but the gears are listed as NLA...
 

Bondo

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Re: Rebuild Alpha One, Change Gear Ratio?

or is it complicated? Any special tools required?
Ayuh,... I send mine out to a Bud, who builds 'em All day long....

Just the toolage is about the price of a brand New drive...
 
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Re: Rebuild Alpha One, Change Gear Ratio?

This kit claims to have everything needed to do the change. I've never worked on a drive before aside of the water pump. Is it fairly straightforward, or is it complicated? Any special tools required?

http://cgi.ebay.com/ebaymotors/Gear...9293221QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

I have bought from them in the past and they are a good company do deal with. But I wouldn't even think of doing the job for parts at that cost plus the tools you need.

No ujoints in that kit either. This is a better option. New aftermarket:
http://www.sterndrive.cc/mm5/merchant.mvc?Screen=CTGY&Category_Code=MercruiserAlphaUpperSterndrive
 

greg82255

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Re: Rebuild Alpha One, Change Gear Ratio?

Alright well then building it myself is out, don't want to spend that much $. I looked at SEI, but I have a 1.5 right now and I'm looking to switch to 1.32 - the smallest upper from SEI is 1.47

How much do you think a professional would charge to do the change to 1.32?
 

Don S

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Re: Rebuild Alpha One, Change Gear Ratio?

Ask the people in your area how much. They are the ones that will do it, we sure can't give quotes that they have to follow.
 

joncrisler

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Re: Rebuild Alpha One, Change Gear Ratio?

Why would you want to switch gear ratios ? What are you trying to accomplish? This is going to a taller ratio, so the prop will spin slower. If your trying to tweak performance you would be better off just changing the pitch of the prop, and certainly cost far less. Changing the gear ratio is pretty much the same as rebuilding the upper gearcase- this is not something you want to tackle yourself unless you are pretty handy and have all the tools, and there are a number of special tools required that your local Sears or Snap-on guy does not have.
 

greg82255

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Re: Rebuild Alpha One, Change Gear Ratio?

This is going to a taller ratio, so the prop will spin slower.

How would the prop spin slower if I go from a 1.5 to a 1.32.......? I've heard the reason the 1.32 was used with 454's was because it will spin faster than the 1.5 and therefore push more water through the engine.
 

Bondo

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Re: Rebuild Alpha One, Change Gear Ratio?

How would the prop spin slower if I go from a 1.5 to a 1.32.......?

Ayuh,... 1, 'n a 1/3rd turn of the motor is less than 1, 'n 1/2 is...

Yer turnin' the prop faster to absorb more horsepower...
 

greg82255

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Re: Rebuild Alpha One, Change Gear Ratio?

That's what I thought.. the prop turns faster with a 1.32 and it was used on 454s with alphas. I am looking to get a 383 stroker without having to buy a bravo setup..
 

wca_tim

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Re: Rebuild Alpha One, Change Gear Ratio?

unless you're going a good bit faster than an alpha gear case can go without blowing out, you'll lose some speed going from 1.5 to 1.32... BUT you will gain some cooling capacity (the water pump impeller is after the gear reduction you are changing), and you'll get smoother speed and launch if you're wanting to run a 4 or 5 bladed low pitch prop for water sports...


You can buy the 1.32 gear set rebuild kit with bearings and all for right at 600. I recently broke a set not long ago and looked into it. That's for high quality, us made hardened gears and bearings, the word from a local shop that does a lot of gear cases both mercruisers and merc outboards.
 

wca_tim

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Re: Rebuild Alpha One, Change Gear Ratio?

That's what I thought.. the prop turns faster with a 1.32 and it was used on 454s with alphas. I am looking to get a 383 stroker without having to buy a bravo setup..

LOTS's of people run 383's in front of alpha drives... and the lower the gear ratio, once propped right, the faster it will probably be... I would go with 1.81 or 1.5 gears if i were you... and I've had those as well as 1.32 and 1.61 (currently) gears behind mine. I'll not type a book here, but there's no reason you can't go with whatever ratio you have and in fact there are probably some very good reasons not to go with a 1.32 for what you're talking about... That was the advice I was given by a local "legend" marine engine builder and it has been my experience since then. do some searching, it's been talked about a good bit. Hope this is helpful.

btw. this afternoon I was turning a 25" prop on a 1.61 ratio alpha drive to 6,000 rpms... I was propped down for watersports. With that gear and my current engine, I can and do turn one of my 28' 4 blades to 5500+ rpms with very low slip numbers.... Use what you have...
 

greg82255

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Re: Rebuild Alpha One, Change Gear Ratio?

wca_tim, are you running a 383/alpha? If not, what are you running? A small block I'd assume.. I'd like some more details - whats the weight/length of your boat, how much HP and mph are you getting out of the motor and what speed do you get with that 28" prop? I have a Formula 206, 3250 lbs and I wanted to drop in a 383 stroker to get some more speed out of it.
 

wca_tim

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Re: Rebuild Alpha One, Change Gear Ratio?

wca_tim, are you running a 383/alpha? If not, what are you running? A small block I'd assume.. I'd like some more details - whats the weight/length of your boat, how much HP and mph are you getting out of the motor and what speed do you get with that 28" prop? I have a Formula 206, 3250 lbs and I wanted to drop in a 383 stroker to get some more speed out of it.

17' 5" Checkmate. probably 2500 pounds or less as it sits with a full tank of gas. "heathy" 383 small block, probably an honest 450ish horsepower right now. I've run a variety of drives and props. fastest (sustained) speeds deep into the 80's by gps.
 

greg82255

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Re: Rebuild Alpha One, Change Gear Ratio?

Sounds like fun. I just sold my 19' Checkmate with a 305. Did about 57 on a good day. I thought about re-powering it but I was afraid the hull wouldn't hold up going that fast. Bought the Formula and now I want to put a 383 in that. Looking around at for different options now - US Engines seems to be the cheapest right now.
 

wca_tim

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Re: Rebuild Alpha One, Change Gear Ratio?

I had the bottom end built by a offshore racing engine builder... forged steel crank, ibeam rods, dished forged pistons, arp bolts, studs, etc.. block, everything blueprinted and balanced, block zero decked, add... afr195 heads, hardened one piece pushrods, comp steel roller rockers, large oil pan, oil cooler, airgap rpm intake holly 750 dp with proform body, quick fuel base, imco powerflow exhaust manifolds with long risers, comp marine grind cam, etc... set it up this time with intention of eventually putting a blower on it... but I'm kinda chicken to do it in this boat. It's a lot of fun now and not too much of a handful if you aren't stupid about it. another 100 - 150 horsepower could be scary... oh, I gutted the interior of the boat and engine compartment, all new stringers, floor, interior, etc... the hull is solod as a rock. I also took the hook out of it. definately won't handle water the way your formula will, but the light padded shallow v runs fast and stable with trim tabs and especially with the alpha ss drive I did have on it (that will go back on it when I quit spending so much time skiing and pulling kids around and make time to work on it). good luck with your upgrade - sounds like fun. that's a well built hull, you should be able to power it to the point of silliness... if you choose to... ;-)

I like your choice of hulls. I'm in the market for a project that'll handle heavier water and has alot more room - formula is at the top of the list... but looking in the 23-25 foot range. The current boat started as more of a learning experience before getting into something I can't afford to fix if I break it.
 

joncrisler

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Re: Rebuild Alpha One, Change Gear Ratio?

Yup, I was tired and got it backwards. Taller gear turns prop faster, but unless you got extra HP and RPM your not using, its not going to make to boat go faster.
 

joncrisler

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Re: Rebuild Alpha One, Change Gear Ratio?

I also took the hook out of it. definately won't handle water the way your formula will, but the light padded shallow v runs fast and stable with trim tabs and especially with the alpha ss drive I did have on it (that will go back on it when I quit spending so much time skiing and pulling kids around and make time to work on it). good luck with your upgrade - sounds like fun. that's a well built hull, you should be able to power it to the point of silliness... if you choose to... ;-)

I have not met anybody with an Alpha SS for a long time. If you put that back on, you should put a drive lock on it- my buddy down at the river had his stolen off his boat while it was on the rack. I caught somebody preparing to steal my Alpha SS at our local marina while it was parked on the trailer. Its probably the CLE gearcase that draws them in. There used to be a guy in Florida that made a special hose fitting to allow the CLE gearcase to be run off the hose- best $20 I ever spent but I dont know if he is still around. Without that adapter its pretty hard to run them on the hose as muffs dont work.
 
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