Alpha, Gen.II lower unit interchangability,...

[Leedanger]

Re: are lower mercrusier units interchangeable

Here is what I have learned through chats with Sterndrive engineering, consulting the Mercruiser Service Manual 14 and counting the teeth on my exploded lower unit.

Not all Alpha 1 Gen2 outdrives share the same lower end.
Thus the ratios are not ONLY in the upper.

- IF you have a 2.00:1 or a 2.40:1 drive the lower unit is geared differently (12 tooth pinion, 24 tooth forwardgear 2:1)
- IF you have a different ratio drive the lower unit is geared with a more common ratio (13 tooth pinion, 21 tooth forwardgear 1.62:1)

Technically the lower ends are interchangeable and you can reprop, but if you want to stick with factory ratios on a 2.00:1 or 2.40:1 drive you will need a lower end with 2:1 ratio.

(I have found out that my lower unit on my 2.00:1 drive that the lower unit was swapped by the previous owner with the other 1.62:1 lower unit, I am curious what will now happen when I reprop with the correct lower unit. )

Paul.

I know this thread is ancient but it's literally what I have now except backwards. The upper is a 1:62 and the lower is a 2:1. Any negative consequences for matching these two?

 

[Bondo]

I know this thread is ancient but

Ayuh,.... You've been 'round here long enough to know that postin' in an antique thread is against the house rules,....

Here at iboats, ya start a New thread, 'n ask yer question,....

 

[alldodge]

Note the gears below and I don't see a 12 24 gears

 

[Leedanger]

My apologies.
I would like to Frankenstein a drive together and I'm wondering if I can do this consequence free.
Upper unit serial: 0L117962 1:62R

The lower unit that I would like to mount to it is
Lower unit serial: 0W811758 2:00

Please excuse my poor forum etiquette.

 

[alldodge]

The full 1.62 drive uses 24/24 upper and 13/21 lower
The full 2.0 drive uses 24/24 upper and 14/28 lower

Note: both the 1/62 and 2.0 use the same upper gear sets, only the lower changes in this case to get the final ratio
If you install the original 2.0 lower on the original 1.62 upper you will have a full 2.0 ratio drive

Only way to get a 2.4 ratio is have upper gears of 20/24 and 14/28 lower

To answer your question if you can put the two together without is, then Yes you can
Only issue would be is if you had a 1.62 and went to the 2.0 you would need to increase pitch quite a bit

I hope this helped answer your question

 

[Leedanger]

The full 1.62 drive uses 24/24 upper and 13/21 lower
The full 2.0 drive uses 24/24 upper and 14/28 lower

Note: both the 1/62 and 2.0 use the same upper gear sets, only the lower changes in this case to get the final ratio
If you install the original 2.0 lower on the original 1.62 upper you will have a full 2.0 ratio drive

Only way to get a 2.4 ratio is have upper gears of 20/24 and 14/28 lower

To answer your question if you can put the two together without is, then Yes you can
Only issue would be is if you had a 1.62 and went to the 2.0 you would need to increase pitch quite a bit

I hope this helped answer your question

Wow yes thank you sir that's very helpful. That chart listed above is great too I saved it. I sure am thankful for all you guys on here that take the time to answer.
Cheers