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AQ280 gearbox split ring space rwear

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joe_merchant

Regular Contributor
Before putting the gearbox back on the outdrive, decided to check the clearance between the split ring spacer and the top nut on the gearbox. The manual calls for clearance of 0.004-0.020". Mine is at 0.013".

Wondering if I should go ahead and replace the washer now, even though it's still in spec. I don't want to fall into the "if it ain't broke - fix it until it is" camp but want to be proactive with regard to potential problems. This is a 4 cylinder with a left hand prop and only put on about 50 hours per year.

Is it something I should be concerned with now or just button things up, wait for spring, and go boating?

Page from manual is attached below:
View attachment split ring spacer install.pdf
 
A very great and smart question to be asking.
This part is often over-looked, and not replaced when it should have been..... even by so called Volvo techs.

Your dimension would appear to be within tolerance. However, here's the concern.

If you have the transmission apart, remove the brass split ring keeper.
With a dial indicator caliper, use the jaws to check how "parallel" each side is to the other.
Just place the piece in the jaws, and hold it up to a light source.
If these are very parallel, then this part is NOT expanding.
If you see that they are NOT parallel, then some expanding is occurring.
(this can also be done without removing it, if you have experience at knowing what an "expanded" part looks like)

LH single prop lowers, and all Duo Prop lowers, both drive from the lower "driven" gear.
This places a very heavy Up-Lift on the vertical shaft.
The split ring and keeper "checks" this up-lift.
If/when the keeper were to fail under load......, the vertical shaft rockets out the top cap.
It makes for an ugly sight, and an expensive repair.

Again..... if no expansion, and on the 4 cylinder engine, your risk is not quite as it could be.
Even so..... it is a relatively inexpensive part to replace.
I've seen these with years and years on them....... and no expanding.
I've also seen relatively low hour transmissions, where there is expansion.
Repeated hard hits into lower gear engagement, will also expand these.

Later transmissions went to a steel keeper..... it will not interchange.

Good luck!
 
Thanks so much for the advice. I took a close look at the ring and for the life of me, could not find a split anywhere. Since my gearbox is a very old model, perhaps they used a solid brass ring at that time. It does not appear to be expanded although it is just slightly off center. The reason I say that it's off center is that you can tell it's slightly under the nut on one side and an equal amount out from the shoulder of the nut on the other side. Lacking any indication of a split on either side, I'm leaning toward it being one solid piece.

At this point, I think I may want to leave well enough alone. I don't have a special holder for the shaft for removing the nut so am a little reluctant to start reefing on it - from the perspectives of both taking it off and being able to hold the shaft while torquing it back down. I just don't want to start getting into something that may cause more problems when it appears to be a non-issue to begin with.

If you disagree, please feel free to say so.
 
joe_merchant said:
............... and for the life of me, could not find a split anywhere.
Since my gearbox is a very old model, perhaps they used a solid brass ring at that time. It does not appear to be expanded although it is just slightly off center.
The reason I say that it's off center is that you can tell it's slightly under the nut on one side and an equal amount out from the shoulder of the nut on the other side. Lacking any indication of a split on either side, I'm leaning toward it being one solid piece.

If you disagree, please feel free to say so.
Click to expand...
Joe, I believe that you may be confusing the reverse threaded top shaft thrust nut, with the lower end shaft split ring and brass split ring keeper.

The split ring(s) fit into a groove that is machined into the lower section of the vertical shaft.
Prior to the top thrust nut being installed, the shaft is lowered some, the split rings are inserted into the groove, then both ring halves become captured by the brass split ring keeper (aka wear washer) as the shaft is drawn up-wards again!
This brass keeper is a 1 pc unit!
The top nut is also a 1 pc unit, minus a 1 pc bronze washer that is part of it!

This "lower" brass piece (that captures the rings) is the one that can and will expand over use...... especially under the fore mentioned conditions.

See an exploded view.
It will clearly show the split rings, the brass keeper, and the top nut.... of which does have a bronze thrust washer crimped to it.

This splilt ring, and the split ring keeper, has been in use clear back to the very early 200 drives, and I believe even further than that.
Your 280 does indeed have this part.
 
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Re: AQ280 gearbox split ring spacer wear

WOW - I was really off!!!! Thanks for setting me straight.

My brother and I will will go take another look.
Helper.jpg
 
The "split ring" is re-usable...... the brass split ring "keeper" is the wear item! (single piece.... quantity = 1)
 
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