Shimming Upper Gear Unit on a 270, Professionals and pulling teeth

[Nickypoo]

Hello everyone, I'm in the middle of reconditioning my 270 outdrive off my AQ125a setup due to bad watertube seals. I pulled it apart, sandblasted it, painted it, and now finally reassembling it with new seals.

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The lower gears were fairly straightforward. I reused the old shims and then checked the gear mesh pattern with a permanent marker. The mesh pattern looks like that from the service manual.

Now I've come to the upper gear unit. This unit is way more complex, and I realized that I don't currently have the capability to do it correctly. I mixed up some of the shims so now I'm a little lost.

I thought I might just have a professional shim it, but as usual it seems like to get a pro to do something on this boat is like pulling teeth. I called the local Volvo Penta service specialists to get an estimate for them to do it. The person I was talking to asked what the condition the rest of the drive is in, if I've pressure tested it, etc. I said the water tube wasn't sucking up water, so I took it apart and decided to paint everything and replace all the seals while I was at it. They say, in a condescending tone I might add, "Well, the water tube doesn't suck up water". The water tube doesn't suck up water! I just said, well yes it does, if the seals are bad then the impeller can't pump water. They took my email and are going to get back to me .


So now I'm back to considering tackling it myself. My questions are below:

• I'm thinking about buying digital calipers and using a depth base instead of a depth micrometer. Would this be sufficient for the job? I'm thinking about future use. If I buy the calipers I will use them many more times. The base micrometer will be used once.
• How much should it cost to have a pro do the shimming? I was thinking if it was around $50-$70 then it may be worth it.

Thanks in advance.

 

[Don S]

Re: Shimming Upper Gear Unit on a 270, Professionals and pulling teeth

They are not easy to do, and to properly re-shim one takes the correct tools and training. I have been to the Volvo drive schools and rebuilt and re-shimmed many an upper and lower. Volvo pays dealers 4 hours for warranty rebuilds, and it usually takes at least all that to get it all right.
You have to get all the preloads, gear patterns and backlashes right all at the same time or you loose the upper gears really quick.
Without the special tools, I don't know how you could do it. And trust me, a new depth micrometer and calipers isn't even a good start in the tools needed.

 

[Nickypoo]

Re: Shimming Upper Gear Unit on a 270, Professionals and pulling teeth

Well it looks like I have no choice Don.

They emailed me back and said that they flat out wouldn't do it, due to "previous commitments" and "liability issues". This upper gear unit must not be a joke if the Volvo Penta Parts and Service specialists won't even touch it.

The shims are mostly in order. I kept track of the shims for the forward and reverse gears. The shims I'm concerned about are the ones from under the clamp ring. Somehow I've ended up with 6 shims, and the gap under the clamp ring is like 1mm. The workshop manual says there's a limit of like 0.1mm on that gap.

Are there any other bearing interfaces that use that same size shim? I don't remember how many shims there were when I pulled it off, but 6 seems excessive. They all have rust on them so they are in an exposed area.

 

[Don S]

Re: Shimming Upper Gear Unit on a 270, Professionals and pulling teeth

This upper gear unit must not be a joke if the Volvo Penta Parts and Service specialists won't even touch it.

Sounds more like your local dealer is a joke, not the gear box. That gear and shifting setup has been used since the mid 60's.

 

[Nickypoo]

Re: Shimming Upper Gear Unit on a 270, Professionals and pulling teeth

Sounds more like your local dealer is a joke, not the gear box. That gear and shifting setup has been used since the mid 60's.

I didn't mean to say the drive was a joke, I said the drive must *not* be joke since they won't touch it. I was implying that shimming it is a pretty serious undertaking. But yeah, I'm pretty disappointed with their response.

Do you have any idea about the clamp ring shims I mentioned in my previous post?

 

[Don S]

Re: Shimming Upper Gear Unit on a 270, Professionals and pulling teeth

Do you have any idea about the clamp ring shims I mentioned in my previous post?

In the upper, there are shims on either side of the double bearing box where it goes into the clamp ring. There isn't any other place on the upper that I remember right off. Haven't rebuilt one of the old style like that in a lot of years.

 

[Nickypoo]

Re: Shimming Upper Gear Unit on a 270, Professionals and pulling teeth

At this point I don't know what other options I have other than doing it myself, no matter how insufficient that is. So with that in mind:

Is the gear wear pattern the "bottom line" as far as alignment? (Besides backlash)

I'm a mechanical engineering student and while I don't have much experience at the moment, I think I can do an adequate job if I take my time.

 

[Don S]

Re: Shimming Upper Gear Unit on a 270, Professionals and pulling teeth

Is the gear wear pattern the "bottom line" as far as alignment? (Besides backlash)

They work together, and backlash on both the upper and lower gears have to be right with the pattern in the correct location.
Also make sure that large left hand threaded nut gap is correct. Not uncommon for the brass washer the cir clips set inside of being distorted.