Changing upper gears...

[wca_tim]

I want to change the upper gears in late 80s alpha drive I just bought. It currently has a heavy duty 1.32 gear set in it. Do I understand correctly that if I want to install a 1.65 gear set, that I will need to get new bearings that are sized for the other gears? I've got someone good to do it for me since I don't have the shim tool yet, but want to get everything together before I take it out there to him. I'm also running the drive on the boat and don't want to take it off until i'm ready to have the gearsets swapped.

thanks!

 

[jtybt]

Re: Changing upper gears...

I'm showing different #'s.



1:32 drive gear bearing 31-35988A 3

driven gear bearing 31-66818A 1

1:65 drive gear bearing 31-35988A 12

driven gear bearing 31-35990A 1


upper bearing 31-61100A 1

 

[wca_tim]

Re: Changing upper gears...

I'm showing different #'s.



1:32 drive gear bearing 31-35988A 3

driven gear bearing 31-66818A 1

1:65 drive gear bearing 31-35988A 12

driven gear bearing 31-35990A 1


upper bearing 31-61100A 1

That's what I saw when I looked too. this is actually an alpha ss drive. They were only made with the limited production "heavy duty" gearset in either 1.5 or 1.32. I am thinking that the 1.65 gears (new, hardened) I have will work, but that I'll need to get a different bearing set(s) to go with them.

although it was kind of fun to be cruising down the river at 50 turning 3200 rpms this afternoon... I thought they were 1.5 gears (no markings on outside) and so put a 23" prop on the boat as a starting point.

 

[jtybt]

Re: Changing upper gears...

The SS 1.32 shows the same bearings.

 

[captdre]

Re: Changing upper gears...

this might come in handy http://www.thestraycat.net/files/Volvo Penta Workshop Manual.pdf

 

[wca_tim]

Re: Changing upper gears...

this might come in handy http://www.thestraycat.net/files/Volvo Penta Workshop Manual.pdf

hmmm... maybe... but I'm not sure when. Thanks, I think...

 

[Haut Medoc]

Re: Changing upper gears...

SS Drives with 1:32 gears are relatively rare & not cheap....
I wouldn't be surprised if you could sell that upper for the price of a brand new upper with the correct ratio all ready installed....

 

[wca_tim]

Re: Changing upper gears...

SS Drives with 1:32 gears are relatively rare & not cheap....
I wouldn't be surprised if you could sell that upper for the price of a brand new upper with the correct ratio all ready installed....

You're right - I hate to admit that I paid about the same as a whole new sei drive plus a new sei upper for this drive... It's in amazingly good shape...

The standard alpha upper is 2 1/2 inches taller than the ss - already makes a huge difference on handling and getting the boat up out of the water. I could pretty easily turn a 23" laser 2 to 5000 rpms with the 1.32 gear.. The other issue is that the ss lower won't bolt up to a standard alpha upper.

The point in doing this is to run enough mechanical reduction to give me the torque to spin 27 - 30" props pretty close to the bottom of the pad at 5300 - 5500 rpms wot... I've got a set of hardened 1.65 gears and need to get the right bearings to go with them so I can cryo treat both before having them replaced in the upper... then the ss drive goes back on with a land and sea sternjack.

Hope that helps with context... Thanks a lot fot the thoughts

I also have a complete sei 1.65 drive, older lower half and new upper half I bought right before finding the ss for sale. and trust me, I'm not throwing the 1.32 gearset away.