89 omc cobra upper yoke/water pump shaft

[shimano]

Took my cobra apart this year for service only to find the small bearing on the end of the yoke shaft shot,could not even remove it from the shaft.got a new shaft,bearing and all the seals/gaskets.I was wondering about shimming.Once I press the old components on the new shaft, would I be able to shim it the same amount it was.Or is there a way to measure what shim you need without the special tool.Thanks

 

[cr2k]

Re: 89 omc cobra upper yoke/water pump shaft

I would check a manual. I believe the shimming also sets the gear tooth pattern and/or bearing preload. Neither of which you want to be off.

The reason shims are used in the first place is because no 2 parts are exactly the same (even in this day of CNC machining) and the shims compensate for the differences.

 

[havasuboatman]

Re: 89 omc cobra upper yoke/water pump shaft

The process involved for replacing the u-joint shaft is quite involved and requires special tools that are very job specific.
You are setting bearing preload, backlash and gear clearances. Get them wrong and you have a drive that whines like hell until it fails if its too loose, or overheats and grenades if it's too tight.
I strongly suggest you have someone that know how to do this, do this.
When you put the bearings and gears on the new shaft, did you even check the bearing preload? THIS IS CRITICAL.

 

[shimano]

Re: 89 omc cobra upper yoke/water pump shaft

I haven't put the old parts on the new shaft yet,But my manual says to press them on till they bottom out ,The preloads are done when puttin the shaft in the upper drive.I realize the preloads are important and don't want to screw anything up that is why I asked the question.Being a new shaft I quess it could be a c-hair different even though I'm using the same gears,I will try to borrow the tools and do it by the book.In the book it tells you after how much torque it should take to turn the driveshaft after replacement,Just wondering if I am in this range have I shimmed properly?Thanks

 

[ENSIGN]

Re: 89 omc cobra upper yoke/water pump shaft

You're going to have to check the rolling torque,It's the only way that you can shim it right.As has been said to tight or loose and you're SOL!