Small spacer with new upper drive bearing set

[boatwaters]

Doing a reseal on an alpha gen ii upper and replacing the bearings on the drive gear as well as shimming (I have all the tools/book etc...). I'm replacing the bearings because they were rusted and you could easily feel it as you spun them. The new set of bearings came with an extra small spacer and no instructions, I don't see this spacer anywhere in the manual. After reading online I found that in some cases I should use it and some not. I unfortunately don't know the model or serial number from the drive but do know that it is a 1991 boat with the original merceruiser engine in it. I am reusing the old gears as they are fine.

If you look in book number 14 on page 3A-24 on the top I have the earlier style where you have to put the hose clamp around the big spacer if that helps.

Should I use this small spacer as well as the big spacer or just use the big one? Thanks.

 

[boatwaters]

Re: Small spacer with new upper drive bearing set

The book page I mentioned is the 2001 book so it might be different in others.

 

[boatwaters]

Re: Small spacer with new upper drive bearing set

Just found some more info that might help
Drive #OD586098
Gear set # 43-45814A5(using original gears and they both have 24 teeth)
New bearing set is 31-35988A12

Service Bulleting 90-18 Reads:


31-35988A12 Bearing Set
Recommendation
When using the 31-35988A12 bearing set on any gear set other than the ones listed following, follow
the “Important” listed below.

43-18411A2/43-45814A5
43-55778A3/43-75325A3

Important
The latest Alpha One Stern Drive units, beginning with S/N OD492656 and above, no longer use
the center cone spacer between the bearings on the U-joint assembly to set the bearing preload.
A new procedure has been established for adjusting this preload. The new procedure is covered
in the instructions that come with the above listed gear sets. The O.D. of the drive gear hub was
increased by .0014 inch, which means that the bearing cones (old or new) now have a slight “interference fit” with the gear. It is important to note that these gear sets and bearing sets will backfit to
drive units that fall below the above listed serial numbers and that the new bearing preload procedure must also be used for those units. In those cases where the 31-35988A12 bearing set is used
in conjunction with the original gear, the cone spacer with the bearing set MUST BE USED, and the
old bearing preload procedure (listed in the Alpha One Service Manual 90-12934--1) must be followed.

 

[boatwaters]

Re: Small spacer with new upper drive bearing set

I'm thinking I should just discard the small spacer and only use the big one even though I am using original gears. It seems like the small spacer is only used on some generation 1 drives and I'm doing a gen II. But someone's thoughts on this would be nice.

 

[Bt Doctur]

Re: Small spacer with new upper drive bearing set

Depends on the gearset used. did you have to pry the bearings off the gear or just hand pressure to slip them off?
make it easier to set the preload with it. you just torque the nut down.
Not using the spacer requires you do to use the "rolling torque " method
please send me the thin one if not using it.

 

[boatwaters]

Re: Small spacer with new upper drive bearing set

I completely forgot when you have to use a press to take the bearings off that means no spacer. Yes I had to use a press. Luckily I didn't put the spacer in and did rolling torque, which I'm happy with how it came out. In the past I've always questioned how I did it but this rolling torque went smooth as well as the shimming. Thanks for the reply boat doc. If you want me to send you the small diameter spacer just give me a pm.