glassdave

any body know what gear ratios were avaliable in Alpha drives. i know the 260hp merc had a 1.50/1 but what else was there. i have a few i am trying to identify. thanks.

amarket1

They came in 1.50:1 , 1.65:1 , 1.84:1 , and 1.98:1. Also I think that the Alpha SS drive came with the 1.32:1 but I will have to check on that.

Darkspoilerzx

The alpha and the ss both came in the 1.32 gear, It was originally hooked to the 330 hp big block 454 mag. Ed

glassdave

thanks guys . . .thats what i needed., is there any way to know what they are or is it going to have to be done by counting input output revs?

cuda

I think the 1:50 has now been changed to a 1:47 is what I read. I don't know if it's an actual change, or just being more precise.

Darkspoilerzx

Most of the gears have a part number on them that wil tell you what they are. Other wise count teeth. The 1.65 ratio also has or had timing marks on them as they are non-hunting gears. Remember the gear ratio is over all for the whole unit, but it is changed in the upper, all the lowers are the same. Ed

Big Block Billy

Count the teeth ! Write the number of teeth for each gear.
Go to mercruiserparts.com and lookup driveshaft housing under alpha drives. The various gear sets will be listed with the gears and tooth #'s. Really should get the book and tools to do this right if you're gonna swap gears. You will probably need shims, bearings(they are different with different gear sets) Etc.
I've had drives blow up when I had to depend on a local marina to do them.
You could spend half a day shimming an Alpha upper.
The bearing races have to come in and out, and shims moved around, and rolling preload also set on the driveshaft by removing or adding shims under the top cap.
Basically it has to be partially assembled, dissassembled over and over 'till it's right. BBB