Replacing yoke assembly Alpha one Gen 1

[fairshopperguy27]

I just acquired a 1987 project boat that came with a Alpha one Gen 1 outdrive. I pulled the drive off and behold some U-Joints that are the scariest I've ever seen! Covered in chunks of rust, massive corrosion. just bad. So I bought a nice used yoke assembly online and by the looks if it, it seems like it would be pretty straightforward to put in. replace the oring seal, unscrew the old assembly and thread in the new one. Any specific things one should be aware of? Thanks

 

[wrench 3]

By your description of the job, I'm assuming that the "yoke assembly" includes the gear and bearings. Problem one is that you can't mix and match used gears. Problem two is that if you replace gears and/or bearings the unit has to be re-shimmed.
To get around this you could replace only the yoke. Putting your old gear and bearing assembly on the replacement yoke. If you reassemble everything in the same positions it shouldn't affect the shimming. Follow the bearing preload instructions and you will need a tool to tighten the bearing retainer. It has to be torqued to 200ft/lb.

 

[JerryIrons]

If you had ujoints covered in rust, then previous owner probably had a bellows rip allowing water intrusion. Which may have affected the gimbal bearing as well. In addition to what wrench said, that drive (I have one) yoke assembly if taken apart has a nut in there that either has to be tightened down to a specific torque or tightened down using a special rolling torque wrench, it depends on year made so to speak. The gears in these outdrives all have carefully measured tolerances and shims used to assemble them, so that they aren't too tight or too loose and wear out quickly.

 

[fairshopperguy27]

By your description of the job, I'm assuming that the "yoke assembly" includes the gear and bearings. Problem one is that you can't mix and match used gears. Problem two is that if you replace gears and/or bearings the unit has to be re-shimmed.
To get around this you could replace only the yoke. Putting your old gear and bearing assembly on the replacement yoke. If you reassemble everything in the same positions it shouldn't affect the shimming. Follow the bearing preload instructions and you will need a tool to tighten the bearing retainer. It has to be torqued to 200ft/lb.

It's the yoke & the U joints that are corroded beyond repair. Are you saying I can just remove those from the bearing carrier and switch them out with the new/used one I bought? Also when you say reassemble in the same position should I mark teeth position on the gears when I pull it off?

 

[Bt Doctur]

First ,do you have the manual? This is the most important tool available. Being an `87 and if the gearset has never been replaced that all you should have to do is remove the nut, slide the bearings off, and slide the gear on to the new yoke assembly and tighten the nut.When you remove the gear with the bearings, look for a small inner spacer ring. If it is there ,you tighten the nut down to spec. Install the assembly using the same shims that were removed.

 

[Bt Doctur]

http://www.boatfix.com/merc/Servmanl/6/6A3R3.PDF

 

[FreeBeeTony]

Also when you say reassemble in the same position should I mark teeth position on the gears when I pull it off?

You only need to mark the gears (and install them in the same position) if the drive is a 1.65:1 ratio as the drive and driven gears have the same number of teeth.

 

[fairshopperguy27]

You only need to mark the gears (and install them in the same position) if the drive is a 1.65:1 ratio as the drive and driven gears have the same number of teeth.

Thanks for the info on this, I'm working with the 1.98 ratio.

 

[wrench 3]

Sorry if I wasn't clear on the "reassemble in the same position". I was referring to the bearings. Make sure that the bearing cups are matched up with the same cones.
Check page 19 on the link on post #6 for tightening the nut on the yoke. And don't skip using the hose clamp or you won't get it back into the housing.

 

[fairshopperguy27]

Sorry if I wasn't clear on the "reassemble in the same position". I was referring to the bearings. Make sure that the bearing cups are matched up with the same cones.
Check page 19 on the link on post #6 for tightening the nut on the yoke. And don't skip using the hose clamp or you won't get it back into the housing.

OK thanks for all the advice! I picked up a Mercruiser manual. I'm going to tackle this one next week. I'll let ya know how it goes with some pics hopefully.