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Mercruiser Alpha ratio question.

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burkstar

Contributing Member
I have a Merc 470 with a Alpha one MR outdrive 1:84 ratio,
The lower leg had become heavily corroded and holed and the upper casing had started to look tired so I purchased a later and complete 1998 Alpha 165R outdrive what looked like very good condition and replaced the upper 1:65 ratio gear with the 1:84 ratio gear from my old leg.

All seems fine other than I do not seem to get the same performance as previously. Is the lower gear also different and have I made a mistake and messed up my gear ratio ???

Please help.
 
There are two different lower gear ratios available. A 1:65 upper with a high altitude lower would give you a final drive ratio of 2:00 to 1
The years of your drives do not make sense. A 1998 drive would be a generation 2 drive and is not compatible with an MR drive.
 
All seems fine other than I do not seem to get the same performance as previously.
Click to expand...

Ayuh,... How did ya get it to Shift,..??

The Gen.II upper shift linkage is Totally different than yer old drive....
 
Sorry my typo error, the leg I purchased is a 1993 and is an alpha one.

All went together perfect, just lacks performance but as the lower leg gearing as mentioned is the same I guess the problem must be else where.

Thank for all your help.
 
burkstar said:
Sorry my typo error, the leg I purchased is a 1993 and is an alpha one.

All went together perfect, just lacks performance but as the lower leg gearing as mentioned is the same I guess the problem must be else where.

Thank for all your help.
Click to expand...

There are two different lower gear ratios available. A 1:65 upper with a high altitude lower would give you a final drive ratio of 2:00 to 1
The years of your drives do not make sense. A 1998 drive would be a generation 2 drive and is not compatible with an MR drive.
 
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