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Whatbs this Oring for HELP

ryan00tj

Contributing Member
Rebuilding my two Alpha 1 driv

Rebuilding my two Alpha 1 drives. Merc #6 service manual shows a flat O-ring under the driven gear in top gearcase. Neither of these two drives had one when dissasembled. One drive was factory assembled and no O-ring. I do not see any reason it is needed. Is this o-ring necessary? Whoever assembled these before did not think it was necessary. Thanks
 
"Got a picture? How big is it?

"Got a picture? How big is it? What is it made of? If it's metal, it's not an O ring, its a washer. There's a difference. Does the manual apply to your serial number? It will show the range and if yours isn't in there, get the right manual. Merc supercedes things all the time.

What is it called in the manual- O ring or pre-load washer? If it's metal, a few thousandths thick and goes under the drive shaft, you should check the pre-load before assembling it further. These washers tend to stay in place and fall out in the parts washer, not seen until after everything is together again."
 
"Are you talking about the ver

"Are you talking about the vertical shaft oil seal(s)? (pc #5) or the shim (pc# 28)?

The oil seal is pretty obvious, you need it.

The shim may or may not be there depending on the actual gear alignment. Their absense may be one of the contributing factors leading to your rebuilding of the drives. There are measurements to be taken to properly shim the gears. Your book should have a detailed procedure."
 
"The rubber O-ring is a specia

"The rubber O-ring is a special flat oring used where the short stub shaft is pressed onto the driven gear. Further inspection shows it is designed to seal oil that might bypass where the stub shaft is shouldered onto the driven gear. There is a slight recess on the top of the driven gear where it should be. It's a redundant o ring as any oil that would get by the shoulder on the stub shaft and driven gear would be held by the lower driveshaft oil seal.

It's not a seal or shim, the manual calls it a special flat o-ring. I ordered two today just to be on the safe side. I'm rebuilding just as the manual says. Interesting fact is that my local Merc mechanic says he has never seen or used them before.

My primary drive I tore apart just to replace all the seals, there were no mechanical problems. The spare I bought used and wanted to verify everything was correct. I found pitting on the pinion and F gear in the lower housing along with questionable condition bearings upper and lower. I decided to replace everything while I was in there. I'm putting big power to these with a beefed up SBC and I need them to be perfect.

Thanks"
 
Alpha 1... big power?
Good l


Alpha 1... big power?
Good luck...at least you'll be proficient in rebuilding it.
 
I know Alpha and HP don't

I know Alpha and HP don't belong in the same sentence but I've been lucky so far. I tore up the original R that came on the boat with Nitrous in 1992. I bought a replacement Alpha 1 that year and it has been running fine since. It's outlived 2 400HP small blocks. I'm building the third as we speak. I'm not to worried as I have a light hull with a good pad. I also don't do any WOT holeshots and get out of the throttle when the prop comes out of the water. But if one breaks I have a spare ready.

Boat is a 1984 Hammond Challenger V2150.
 
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