Mercury Alpha One Gen II Upper Gear repair

Djunegarcia

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Jul 24, 2021
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Hi all..I have a Mercury Mercruiser Alpha One Gen II outdrive with a V6 4.3L engine. Recently took the boat out and thought I spun a hub as my prop stopped rotating but engine was still revving. Was towed in now my boat is in my garage. Upon disassembling the Alpha One outdrive I started to remove the upper gear box case. Gear lube “Oil” was not in the upper gear box and gears were sheared smooth. I’ve purchased new upper gears and began a deep cleaning to remove any and all metal shavings/dirt/grime. I am now at a stand still simply because the gear/bearing/ shaft that runs vertical “Up and down” which I believe is called the driven shaft has both a bearing and gear that seems to be pressed on the shaft. Anyone know how I can remove the old gear/bearing off old shaft and put new gear/bearing on the same shaft??
 

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Faztbullet

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15,905
You need to take lower apart also as they share the same oil so all that debris is in lower unit too. You will need a press to remove/reinstall shaft and shim tool to check height. Also will need to check preload on gear/bearings on horizontal input shaft and clearance. Might be best to take to a repair shop and let em set it up. If u-joint bellow had oil in it the yoke has a groove and needs replaced
 

Djunegarcia

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Joined
Jul 24, 2021
Messages
14
You need to take lower apart also as they share the same oil so all that debris is in lower unit too. You will need a press to remove/reinstall shaft and shim tool to check height. Also will need to check preload on gear/bearings on horizontal input shaft and clearance. Might be best to take to a repair shop and let em set it up. If u-joint bellow had oil in it the yoke has a groove and needs replaced
Thank you for the info. Makes sense. As far as preloading gear/bearing this is something I can do at home or is it that difficult that I will need to take it to a shop? Same for the shim tool this is something I can do at home myself? Also U joints had no oil present they only had grease.
 

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Scott Danforth

Grumpy Vintage Moderator still playing with boats
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You need the factory tools, the factory manual and the knowledge from factory training. Can you do it at home, depends on your training and shop setup
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Same boat as your 454? You know that the alpha drive doesnt survive behind a BBC, right
 

Djunegarcia

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Old gear-New gear
I’ll send pics as I complete the work
 

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Djunegarcia

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Jul 24, 2021
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Old gear -new gear
Got it! Right in my garage 👍
 

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Scott Danforth

Grumpy Vintage Moderator still playing with boats
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If you dont get the preload right, or the gear mesh pattern right, the drive will eat itself
 
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