What gear ratio do I use????

[Azlo]

The gear ratio on the outdrives has me a little confused. I have a 140 4 cyl merc with a pre alpha outdrive wich i will be replacing it with a alpha 1. But my understanding is that i need to know the gear ratio of the outdrive to fit or handle my 140. (by the way,, u can you replace a pre alpha w/ an alpha1 right?) How do u test the drive to see what gear ratio it is, turning the shaft & see how many revolutions the prop does? Sorry for so many questions but i been searching & been getting confused.

 

[Don S]

Re: What gear ratio do I use????

The 140's require a 1.98: 1 gear ratio.
That's basically 2 turns of the engine for 1 turn of the propshaft.

 

[truckermatt]

Re: What gear ratio do I use????

if you havent bought the drive yet..... i suggest one of these...

http://www.sterndrive.cc/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=MercruiserAlpha

 

[Azlo]

Re: What gear ratio do I use????

Is it hard to change gear ratios if u change engine or upgrade your horsepower?

Thanks Don & Trucker

 

[HT32BSX115]

Re: What gear ratio do I use????

Howdy,

It's almost like a complete rebuild. Not very cost effective. It's far better to make your decision on engine now, then buy the right ratio drive!


Regards,


Rick

 

[Azlo]

Re: What gear ratio do I use????

Thanks fellas things are becoming very clear!!

Ok fair enough but can I replace the pre-alpha with a alpha gen1 without having to change the gimbal housing? will it just bolt on?

 

[wca_tim]

Re: What gear ratio do I use????

Howdy,

It's almost like a complete rebuild.


Not very cost effective.

Rick, I agree with your second statement, but the first seems a bit overstated, it's not nearly that big of a job to swap out an upper gear set. It's not cost effective because by the time you buy gears, bearings (if required), seals and tools you would have more in the swap than it would cost to buy a new aftermarket upper half (something I just did right before I came a better drive and bought it). I don't see how it is like a complete rebuild...

I still haven't bought the shim tool(s) and want to change the ratio in upper in the older drive I just picked up. I was told it would only cost an hour or two labor. I have the gears and bearings to go in it though...

 

[Azlo]

Re: What gear ratio do I use????

SO is it possible to switch to a alpha 1 from a pre alpha? will it just bolt on?

 

[jaxnjil]

Re: What gear ratio do I use????

i had-have a pre alpha (73 165). i also have a couple of alpha 1's

i haven't looked at the older drive for a while but if memory serves me the older drive has a longer drive shaft. also from memory i think when i was looking, it looked like the drive shaft could be swapped and i thought at the time it would be worth a try if i needed

not a solid yes. perhaps some one who knows for sure will chime in
also i think i read SEI can set up or make a A-1 to swap with the older drives