Re-Seal Upper Drive Unit - Alpha I Gen II

[Gray035]

I have an Alpha I Gen II drive. I took apart the upper drive unit to replace the seals. In order to replace the driveshaft seal I had to separate the pinion gear section (that has the two bearings pressed on it) from the drive line yoke. My question is do I need to have the bearings pressed off of the yoke section in order to have the rolling torque reset? Or can I put the unit back together the way it is, ensuring that the bearings do not get any further snugged?

It seems to me that if removal of the bearings is required, a special tool is necessary. Can anyone help me out with this? I looked through the service manual, and it is unclear on this front.

 

[Bt Doctur]

Maybe ,maybe not. If you assemble it correctly and torque the nut correctly Being gentle and not overtightening the nut you may save the original preload setting.
Should you over tighten you can loosen the bearing package by using a brass hamer to strike the rear of the gear to loosen the bearing package and reset the preload. Do you have the merc manual ?

 

[Bt Doctur]

http://www.boatfix.com/merc/Servmanl/14/14a3.pdf page 3A-15

 

[harringtondav]

I just made a similar repair replacing my gear yoke and yoke seal. You don't need to separate the bearings from the drive gear if they feel smooth. But getting the yoke shaft gear retaining nut correctly tight is critical. Too loose and you loose the preload in the pressed together assy. Could be be big problems for gear wear. Too tight and possible bearing failure.

Get an inch/pound torque wrench. If you don't have a manual, check out achris 's videos at the bottom of his signature. He has a great video showing what you need to do. You will need to sneak up on the nut's torque with a ginger feel. You will know when the nut is starting to compress the washer. After that a 1/8 turn could equal 1 inch/lb. Patience. Check rolling torque. Another 1/8 turn. 6 in/lb max on used bearings.

 

[altitude 411]

I have an Alpha I Gen II drive. I took apart the upper drive unit to replace the seals. In order to replace the driveshaft seal I had to separate the pinion gear section (that has the two bearings pressed on it) from the drive line yoke. My question is do I need to have the bearings pressed off of the yoke section in order to have the rolling torque reset? Or can I put the unit back together the way it is, ensuring that the bearings do not get any further snugged?

It seems to me that if removal of the bearings is required, a special tool is necessary. Can anyone help me out with this? I looked through the service manual, and it is unclear on this front.

This video is a little crude but he does show how it's all done.

https://www.youtube.com/watch?v=_eNBBKhLm3M

Chris's video on setting pre-load is excellent

https://www.youtube.com/watch?v=lPr4...ature=youtu.be

 

[Rick Stephens]

First time I did one, like you are suggesting, I did not press the bearings off and then back on to be pulled together while running the rolling torque. I did buy a 30 inch pound torque gauge wrench. As I snuck up on the 6 or 7 inch pound rolling torque I was pretty timid not wanting to overshoot. Learning experience is I did not get it tight enough and first time I ran the boat within a few minutes I had a rumble. Back off came the drive, pulled the bearing pack and sure enough, too loose. Reset it to spec and been running fine ever since.

In hindsite the process is easier to come up to proper torque if you split the bearings a little. It is tough to tighten up properly when the rolling torque is already near spec before the nut is tight. Just fair warning, cutting corners has its difficulties.

RIck

 

[harringtondav]

As I snuck up on the 6 or 7 inch pound rolling torque I was pretty timid not wanting to overshoot. Learning experience is I did not get it tight enough and first time
RIck

Yep, it takes a good feel and understanding of what is going on. The lock nut's natural torque exceeds the rolling torque in/lb specs. What works for me is to lift the assembly in the spanner/vise and tighten the lock nut until there is zero clearance/movement between the nut/washer and the rest of the assembly. Then it's a painstaking process of 1/8 turn, check drag, another 1/8 turn, etc until you see the rolling drag start to increase...a bit. Then carefully sneak down the nut until you hit spec.