Shim - Shim - i - nee ??

[Craig]

Question on shimming.

Putting a Volvo AQ-280 drive back together. Didn't get the shims with the drive and the upper gear housing and cap were already off.

Need to put the upper back on the intermediate AND the top cap back on the upper.

Measured difference of each and added 0.004" to each to determine shim thickness needed (as directed in SELOC manual).

For the "cap to upper" I get a needed shim thickness of 0.003"

For the "upper to intermediate" I get a needed shim thickness of 0.006"

Shims available are 0.004", 0.008", and 0.016"

QUESTION: What do I do? Put a 0.004" in the cap and a 0.008" between the upper and intermediate?

That would leave me over by 0.001" under the cap and under by 0.002" between the upper and intermediate.

Are the distances described acceptable distances? OR do I address this another way to get closer?

Appreciate any help.

[Craig]

So nobody knows about shimmming? I thought this was the place for all the answers...

Would greatly appreciate replies from any licensed Shimoligist.

[Craig]

Yes Craig -- Shims are very important. Throw a couple in there and tighten stuff up real good. You'll be fine...

[Craig]

Oh, ... are you sure I don't need to be a bit more precise with this?

[Craig]

Naw, you'll be fine. Just tighten it up real good. And remember "shims are important" .. very important, now that I think of it.

[Craig]

Well, okay then.

Thanks for the help!

[harbormaster]

Craig. On a weekday it may sometimes take a little longer to get an answer.

Scot V

[BillG]

I believe that you will find that you need a .000 to.004 gap between the upper cover and the upper gear housing and the same between the upper gear housing and the intermediate housing. This gap is to ensure that the gears are preloaded properly. So after assembly measure the gap and adjust accordingly. You should be able to attain these dimensions with the available shims.
Bill G

[HOTFOOT]

The reason for adding the 0.004 to the measurement obtained by subtracting the two depths is to create a 0.004 inch preload on the outer race of the bearing. This crush effect prevents the outer race from spinning in the housing. When I overhauled my 250 which should be similar there were some 0.002 shims in it so these may be available. Having said all this,as long as you have at least 0.002 preload and the bearing fits the housing snugly it should be OK. You might add a little Loctite to the outer race O.D for added insurance.

[AVickers]

"Setting up differentials and outdrives requires lots of patience..."

That aside, if you can't find .001 or .002 shims from a Volvo Dealer, there's a guy in South Houston, TX who has large numbers of used drive and lots of parts -- new and used.

You might contact them to get shims in the thicknesses you need.

Munson Marine

[Craig]

Thanks guys.

So AVickers, are you saying .001 and .002 shims are available? Munson Marine?

The only shims shown on parts lists I've seen for 280's are, as I said above, .004,.008, and .016.

Are you also saying that my options, detailed above (i.e. coming to within .001" and 0.002", respectively) are not close enough?

I know all about patience. Haven't had the boat in yet this summer! AAAAAAgggggghhhhhhhh!!!!!!!

Actually, this project has been kind of fun and very interesting, but I'm ready to go for a ride now. Just wishing the boat was.

Scot, sorry, I was just soliloquizing a bit!

Craig

[BillG]

Craig,
The preload does keep the race from turning, but the preload lets the bearing carry a larger load than if it just ran without one. It also reduces bearing deflection, a good thing. Without preload a bearing will distort and that is not a good thing.
Bill G

[Craig]

Thanks again for the added input. I also talked to a guy last night who was not only an old Volvo mechanic, but is, himself, also pretty old. Had to clarify that. Ha Ha. He told me, in regard to my original question (above)that .001 and .002 were small enough that he wouldn't worry about it. Said if I was off like .007 or .010 that would NOT be o.k.

Will wait and consider any disagreements with that as I ain't putting this thing all back together wrong after all this effort! Basically looking for some peace of mind.

Bill G. - Thanks for the preload lesson. I had an idea of how things worked and why from the shop manual, but I'm basically just trying to do exactly what it says to get it running without completely understanding the purposes involved in each step. Your info. was interesting.

Madpoodle - I did have check my spelling on "soliliquize". I said to myself: "better check the spellinng on that." Hey, this is a classy web site. Grammar is a little bit important. I think the apostrophe in touch'e is between the h and the e, not after the e.

Of course a worse mistake would be something like "yes .010 is close enough", when you meant .001 !!! Now that's bad grammar!

[Ralph Savarese]

Craig. Check out www.sterndrive.com/boneyard.cfm?cat=Volvo-Penta (http://www.sterndrive.com/boneyard.cfm?cat=Volvo-Penta) talk to them very knowlegeable and helped me greatly.You They have more of a variety than you think!
Ralph

[Moody Blu']

MadPoodle:
C,

Rule of thumb: tighten till just before it breaks, then add 1/4 turn. wink :)

The other scott

I cant figure out how to spell touche' and you are soliloquizing? ? the other scott, that saying goes tighten it till it almost strips out then back it off a 1/4 turn

i should know I build bikes and thats how they told me to toighten the bolts eek! wink

hey craig, whatever your smokin, pass it overhere! :D

[MOP]

The most important step when done with the shimming is to use the Volvo orange gear paste to check gear contact, all should show the same contact and pattern when rotated. Regular bluing should do the same job.

[Craig]

Orange gear paste!?!?!?!?

Oh man! Too late! It's back together. Rode it yesterday. Seems to be okay. My only prop needs repaired or replaced (dinged up a bit) and I think (hope) it may be causing a slight vibration. Not nearly as bad as before when this whole thing started.

If it's something else, I'll take it back a part this winter.

I ain't afraid of it anymore. I am the shim-in-ator!! (not hardly!)

The 280 feels a little different (in a good way) than the 250.

My plastic speedo pickup is broke; but it felt exceptionally fast. RPM's weren't real high (like only 4,000??), but it just seemed faster than before on the same pin setting (had it on the low one - because I had my 3 kids with me).

Thanks for all the help with getting it going again.

[MOP]

You need to get a better prop, what pitch are you runnin now? I doubt if you are getting any vibes from the gear case. Though its possible to have U joint caps out of alignment, bent yoke or a bent prop shaft. I'm in your corner its the prop you have had enough grief.

[Craig]

M.O.P., My prop is an aluminum 14x23 that I had re-conditioned a few years ago and, at the same time, had cup added. It was done by Skip's Propeller Service (I think they're in Pittsburgh - a local (to me) marina sends them to Skip's).

Anyway, it actually ran pretty good (I thought) just after it was done. It would turn 4800 RPM's on my tach. However, there was vibration even then and running through the speed equations, I determined that I must have a considerable amount of slippage because it only ran 52 mph (@4800RPM's w/ a cupped 23" pitch prop).

I sure hope it's the prop and I'd consider just getting a brand new aluminum one to compare. 21" or 23" with some pitch added, I think would be a good all around prop.

Hate to pull the drive again, but I did learn a lot through the project -- just too much time without running it!

It was great to actually go for a ride. Ironic that it was on exactly labor day, the traditional end of boat season around here!