need some shimming tips

[mercs4mark]

Over the summer I decided to tinker with a spare unit I had laying around (alpha one upper). I replaced all of the bearings and mated it with an old lower alpha one and bolted it up to my boat. I ran it on the lake for about an hour and a half and seemed to be doing well. When I winterized the boat this year I noticed the drive was making a whinning noise out of the water on muffs and some metal particals in the lube, fine but present, so yesterday I figured to tear it back down to see what I have done wrong. The bearings look good and my rolling torque is running 3.5-4inlb and my driven gear when checked the hieght was high I think by .002 so I took that amount out and added .002 to the top cup and rechecked rolling torque and gear position and was good.



Now I'm having a little trouble with the drive gear seems when I check its position and determine to add or subtract shims when I do so, and, put it back together it seems to still be out of wack.

just looking for some shimming tips to the trade. thanks

 

[achris]

Re: need some shimming tips

All shimming should be done with the Merc special tools. There is no other way of doing it accurately. I have seen a few people say they can do it with engineers blue, but I doubt it's accurate. Basically, without the tools, you're just guessing, and that can lead to noise, premature wear and eventual early failure.

 

[mercs4mark]

Re: need some shimming tips

I have the shimming tools chris

 

[Don S]

Re: need some shimming tips

Some Alpha's just whine more than others. Everything can be perfect and they will whine.

 

[achris]

Re: need some shimming tips

I have the shimming tools chris

Then just do it 'by the book', and it will be alright. With the tools and a 25 thou feeler gauge, Bob's your uncle....
Merc did change the gears in the lower box in the mid 90's due to 'noise'. What year is the drive you're working on? or serial number...

That lower box gear change also changed the overall ratio a little. The 1.50 became 1.47, the 1.65 became 1.62, the 1.84 became 1.81 and the 1.98 became 1.94....

What oil are you using?

Chris.......