Sleeve gear bushings

Can the sleeve gear bushings be replaced with the gearbox remaining in the cradle? I have everything on the primary side prepped and ready to go, haven’t open the other side yet.

1973x75 said:

Can the sleeve gear bushings be replaced with the gearbox remaining in the cradle? I have everything on the primary side prepped and ready to go, haven’t open the other side yet.

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Yes.

On the bench.


Replace the sleeve gear bearing as well.

How will you remove the old bushes if the clutch shaft is still in the sleeve gear.

1973x75 said:

Can the sleeve gear bushings be replaced with the gearbox remaining in the cradle? I have everything on the primary side prepped and ready to go, haven’t open the other side yet.

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The gearbox shell can stay in the cradle. IMHO, the sleeve gear must come out so almost all the geabox internals must come out. Be VERY sure you need a new bushing before attempting it. There are multiple forms of bushings, none easy to get out, none easy to get in, and it's likely it will need to be reamed afterwards.

The main shaft is pretty sloppy in the bushings, so I guess I need new ones.

Time Warp said:

How will you remove the old bushes if the clutch shaft is still in the sleeve gear.

View attachment 112393

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Pretty sure he asked if it could be done, "with the gearbox remaining in the cradle". Then, went on to explain he hadn't opened the other side yet.
No mention of the main shaft.
I saw no ambiguity.

But, hey, whatever.

marshg246 said:

The gearbox shell can stay in the cradle. IMHO, the sleeve gear must come out so almost all the geabox internals must come out. Be VERY sure you need a new bushing before attempting it. There are multiple forms of bushings, none easy to get out, none easy to get in, and it's likely it will need to be reamed afterwards.

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True . The main shaft bushings do wear out , particularly if the chain or belt adjustments are too tight . Or gearbox oil falls low or contaminated . I've changed them in Situ . All gears must be removed . It can be done . Order in MK 111 ones .

Torontonian said:

True . The main shaft bushings do wear out , particularly if the chain or belt adjustments are too tight . Or gearbox oil falls low or contaminated . I've changed them in Situ . All gears must be removed . It can be done . Order in MK 111 ones .

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If a MK3-type with two circlips, I can't imagine how you would get the inner circlip out with the sleeve gear still in the shell or why would fight it - the sleeve gear is not hard to remove.

marshg246 said:

If a MK3-type with two circlips, I can't imagine how you would get the inner circlip out with the sleeve gear still in the shell or why would fight it - the sleeve gear is not hard to remove.

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I did it on my 72 combat years back . Can't recall details but yes it was done with the gearbox stripped down , yet still in the cradle .

Torontonian said:

I did it on my 72 combat years back . Can't recall details but yes it was done with the gearbox stripped down , yet still in the cradle .

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Sleeve gear still in the shell?

72 Combat would have zero circlips. I don't think the OP mentioned what bike. I would be really shocked to hear that someone with two circlips was able to change the bushing with the sleeve gear in the shell and even more shocked if the sleeve gear was in the shell in the cradle! I learned long ago to not say things are impossible, but...

Also, when you're down to a sleeve gear and sprocket, why do it in the shell?

It’s a 1973 750, and I’m aware that everything has to come out to do this work. I’ve been through the gearbox before, when it was out of the bike, but not for bushings.

1973x75 said:

It’s a 1973 750, and I’m aware that everything has to come out to do this work. I’ve been through the gearbox before, when it was out of the bike, but not for bushings.

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OK, to me, sleeve gear on the bench is quite different than the original question or people saying the bushing(s) can be replaced in situ.

If the actual question is can the sleeve gear be removed from the gearbox shell while the gearbox shell remains in the cradle, the answer is yes, no problem.

The old bushings drifted out just fine, and the new ones squeezed in easily on the vice with the appropriate sized socket to push against the bushings, just like Norman Whites book said they would. I installed three, as recommended somewhere in this forum, maybe one of Hobot’s ideas. Mainshaft spins free, so no need for reaming. I used the genuine article bushings from Andover Norton.

Perfect time for this topic. I too am rebuilding my 73 commando gearbox. All bearings now successfully replaced, I just need to press in the new sleeve gear bushes. I am a little concerned though as my genuine AN bushes measure 0.905" OD and my sleeve gear measures 0.900" ID. That seems like an awful lot of interference fit!
1973x75, I don't suppose you made any of these measurements to compare with? You didn't mention it, but I also presume you had to put a chamfer on the bushes before pressing them in.
So, am I unduly worrying about a 0.005" interference fit?

I didn’t take any measurements, just trusted that everything that got delivered to me was the right size. I didn’t chamfer them, either. What I did, was give them a gentle tap with a small hammer, against the socket of course, and that was enough to set them straight on, then proceeded to squeeze them in on the vice.

BruceB said:

Perfect time for this topic. I too am rebuilding my 73 commando gearbox. All bearings now successfully replaced, I just need to press in the new sleeve gear bushes. I am a little concerned though as my genuine AN bushes measure 0.905" OD and my sleeve gear measures 0.900" ID. That seems like an awful lot of interference fit!
1973x75, I don't suppose you made any of these measurements to compare with? You didn't mention it, but I also presume you had to put a chamfer on the bushes before pressing them in.
So, am I unduly worrying about a 0.005" interference fit?

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Assuming your measurements are correct, the bushings will be forced to shrink .005". Sometimes bushings are made with the shrink in mind - don't know if these are. Try a bushing on the shaft before installing. If it seems loose, you're probably OK, if it feels "right" be ready to ream.

If measuring with cheap calipers, they may be getting the inside and outside measurements wrong. A .001" interference fit takes substantial pressure to install so .005" is a lot! Also, some of the non-AN sleeve gears or old AN sleeve gears may well be a different bore than the ones AN sells today.

Well, I'm using a quality Mitutoyo digital caliper, and all other shaft/bearing measurements have been where I would expect. And the bushings I pulled out had an OD of 0.901", so I think my sleeve gear ID measurement of 0.900" is pretty accurate.

The new bushes fit over the main shaft perfectly, both in feel, and measurement wise with a 0.002" clearance. But presenting the bushes up to the sleeve gear feels a mile off. Absolutely no chance of easing them in to a starting position for pressing.

So I'm wondering if you are right Greg in that I have an undersized sleeve gear. I'm 99% certain it's original. Any chance that anyone out there has a sleeve gear that they could measure the ID? Or perhaps a spec from AN? Thanks.

BruceB said:

Well, I'm using a quality Mitutoyo digital caliper, and all other shaft/bearing measurements have been where I would expect. And the bushings I pulled out had an OD of 0.901", so I think my sleeve gear ID measurement of 0.900" is pretty accurate.

The new bushes fit over the main shaft perfectly, both in feel, and measurement wise with a 0.002" clearance. But presenting the bushes up to the sleeve gear feels a mile off. Absolutely no chance of easing them in to a starting position for pressing.

So I'm wondering if you are right Greg in that I have an undersized sleeve gear. I'm 99% certain it's original. Any chance that anyone out there has a sleeve gear that they could measure the ID? Or perhaps a spec from AN? Thanks.

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I suppose it's possible that the OD of the new bushing is wrong. Since you pulled out a .901" and you have a .905". Try measuring the wall thickness of the old and new. Generally, AN parts are correct but they sometimes get a bad batch of a part and don't always catch it - especially if it's a trusted supplier.

At least it's easier to reduce the OD of the bushing than increase the ID of the sleeve gear. Also, a chamfer on the leading edge of the bushing would hurt nothing and help get it started. I have sleeve gears but all have good bushings so I can't measure for you.

Write technical@andover-norton.co.uk and explain the problem. They may have an answer and if the bushings are out of spec they will want to know.

So I figured this out with a little experimentation, and ultimately a very good outcome.
Before I started my gearbox rebuild I bought a full AN gearbox rebuild kit, which comes with two short (0.88") sleeve gear bushings. I also bought a pair of the later 1.2" bushings, which meant that I had the two short bushings to experiment with. Note that all the bushings did have the same ID's and OD's. The OD's being 0.905". Remember my sleeve gear ID is 0.900"
So with the help of a friend and his lathe, we cut a chamfer on a short bushing and then with the sleeve gear in the chuck and using the tail stock as a press we very squarely drove the bushing into the sleeve gear. Amazingly it went into the sleeve gear without too much force - most of you will know that a tail stock isn't really designed as a press!
With it pressed in about 3/16" we stopped there and pressed it back out to see what it looked like.
As you can see in the photo, the rough sintered surface has been "smooshed" flat. That OD is now 0.902"
With this success, we used the same process to fully press in the longer 1.2" bushings into each end of the sleeve gear.
The wonderful thing is that even though we started with a 0.005" interference, the ID only decreased by 0.0005" and thus no reaming was necessary.

What I took away from this is that these sintered sleeve gear bushings are quite different is structure to the other solid bushings used in the gearbox, and that sintered bushings need a larger interference fit due to the relative "softness" of the material.

Hope this helps anyone facing the same dilemma.

I submerge the sintered bronze bushes in oil the night before to saturate them. It is easier to press in. I use the longer Mk III bushes as these tend to not rotate with in the 4th gear sleeve.
If you use A.N. products you don't need to ream them, at least that is what I have found.
Cheers,
Tom