Another gearbox question

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DogT

DogT

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Got the gearbox apart, most looked in pretty good shape. However, found that the outer bush (nearest the sprocket) on the sleeve gear was missing the outermost part. Any guesses why this happened? Also there are 2 part numbers listed for the bushes, 04-0062 for the old one and 06-6203 for the new model. What if any difference is there in these 2 bushes? Thinking about getting the parts from RGM or Hemmings, RGM only lists the newer bush, 6203, not sure about Hemmings.

Another gearbox question


Another gearbox question



Dave
69S
 
These bushes tend to move and get 'eaten up ' by rubbing against the clutch retaining circlip .
Now its 3 bushes or one long bush .
 
Boy if the bushes move around, that is interesting because I had to use a drift to get them out, they were rather tight. The inside one was still intact and flush with the inside of the main sleeve gear. The clutch locating clip was worn on the outside too, not the inside like if the bush had worn it. Are the new bushes just like the old ones, or is it a longer single bush? I am not understanding completely. I don't understand the 3 bushes either? The OldBritts site only shows the 2 bushes 04-0062 through 75, but they do list the 06-6203 as a replacement. What do I need to order?

Dave
69S
 
DogT said:
Boy if the bushes move around, that is interesting because I had to use a drift to get them out, they were rather tight.
Click to expand...

Apparently it was a problem, as the later 850 MkII/IIA sleeve gears (064991) had a circlip (064989) that fitted into a groove machined inside the clutch end of the sleeve gear.

The MkIII sleeve gear (065954) had a groove and 064989 circlips at both ends.
andover-norton.co.uk

Andover Norton - CIRCLIP - SLEEVE GEAR BUSH - 06.4989

CIRCLIP - SLEEVE GEAR BUSH
andover-norton.co.uk
 
The first picture shows that the bush has moved to the inside .
The bushings that RGM sells are longer : 1.1/4 inch , so they will almost fill the whole sleeve gear .
With the shorter bushings , I used to intall 3 bushings , an old one in the middle for a spacer .
I know there are longer bushings , about 2.5 inch long , with a spiral oil groove cut in .
 
I have to admit that upon inspection of the bushings out of the gear, the outside one certainly looks like it has been moving around. I am assuming that longer bushings will not necessarily stop the movement and "eating" of the bushings? What if I had a machine shop cut some internal slots in the sleeve gear to accept the newer circlips to hold the newer longer bushings in place? Or is this overkill? It looks like the Mark III had a single clip for the inside bushing? Mick Hemmings DVD showed a sleeve gear with a single clip for the outside bush as I remember, he acted like he had never seen a single one? He had to grind a slot to get it out. I'll watch it again today. Maybe I should just get the slot cut for the outside bushing, doesn't look like the inner one can go anywhere.

Dave
69S
 
DogT said:
It looks like the Mark III had a single clip for the inside bushing?
Click to expand...

As I mentioned previously, the MkIII sleeve gears have a circlip at both ends.

Quote from the MkIII parts book:
"06-5954...Gear, Sleeve, With Bushes....1.."

"06-4989....Circlip.....2..."


DogT said:
Mick Hemmings DVD showed a sleeve gear with a single clip for the outside bush as I remember, he acted like he had never seen a single one?
Click to expand...

Mick's comment surprised me too, the first time I watched his NOC gearbox rebuild DVD!

However the sleeve gear is listed in the 850 MkII/IIA parts supplement under a new part number 064991 (061057 previously) presumably because it had the machined circlip groove?

And the "064989...sleeve gear circlip...1.." was added to the bottom of the page list.

I also have a used one amongst my stock of spare parts, so I doubt that type of single circlip sleeve gear is particularly uncommon?
 
LAB,
Yes, I was looking at the OldBritts MKIII site and they only show one circlip. That is where I got that, but I don't have any other MKIII info. I think I will get a circlip and the new long bushes and see if I can get a local shop to machine a groove in it for me, at least on the sprocket side. Anyone have a dimension for the groove and the distance from the end? Thanks,

Dave
69S
 
DogT said:
I was looking at the OldBritts MKIII site and they only show one circlip. That is where I got that, but I don't have any other MKIII info.
Click to expand...

That's strange, as I can see two of them?: http://www.oldbritts.com/image/1975_g6.jpg Item [20] (x2)


And two are listed:
"[20]...06-4989...Circlip, 4th Gear Main...2..."




DogT said:
Anyone have a dimension for the groove and the distance from the end?
Click to expand...

I should be able to find my spare sleeve gear and give you those dimensions in about an hour or so from now (unless somebody already has those dimensions handy?).
 
Has the box been run with hypoid ? That brittle porous look to what started off as yellow bronze is what I've always put down to the deterioration linked to hypoid oils.

I should say that I have no scientific base for this and I've never seen confirmed examples but if the effect does have basis in fact then this sort of failure is what I'd probably expect.
 
There's some useful advice given in the NOC Service Notes:

"Sleeve gear bushes are always coming loose-sometimes the outer bush moves inwards to the centre of
the sleeve gear-then all you need do is to Loctite a new bush in the end. Leave the old one in and it will
prevent the new one moving inwards, i.e. fit three bushes in your 750 a la 850. Sometimes the bush
moves outwards and gradually mills itself away on the sharp edges of the circlip which locates the clutch.
That’s worse because eventually the bush disappears completely and all the pull of the back chain comes
on the sleeve gear bearing. No wonder the bearings come loose. Often the first sign of sleeve gear
bushes going -is striking "gold" in gearbox or primary drive oil, watch it! Here the answer is to buy two
new bushes and a clutch location shim (060894 or 060895). Push both bushes-Loctited on the outside--
into the sleeve gear--the middle one stops the outer from moving in-and then put the shim loose on the
shaft to avoid the bush wearing on the circlip even if it does move. It is an advantage to grind the outer
edge of the shim so it will pass through the hole in the primary case (or file or even clip it away with tinsnips
to about half the radial thickness)."
 
LAB,
You are right as usual. The second clip was off my screen and I didn't look at the parts list. DUH. Boy that NOC note was really helpful. I think I will go for the locktite, since I have to do my Main bearing also since it just fell out when I took the mainshaft out. It's not that loose though, it just doesn't fall back in and I am having trouble getting the layshaft bearing out. I could use the old bushing in the middle like ludwig says.

I think this has been solved to my satisfaction, on to buying parts.
Thanks,
Dave
69S
 
DogT said:
I think this has been solved to my satisfaction, on to buying parts.
Click to expand...


DogT said:
Anyone have a dimension for the groove and the distance from the end?
Click to expand...

OK, here's the circlip/groove info anyway.

Due to its position, the width and depth of the groove is rather diffcult to measure, and although the circlip is circular in cross-section, the groove appears to have a square-cut profile, only wide enough to accept the circlip and is cut to a depth of approximately half the circlip's .047" wire diameter.

With the circlip installed in its groove, the circlip's I/D is: .870". (the bush I/D measures up at .810")

The distance from the end of the sleeve gear to outer edge of the groove is .040"

064991 (850 MkII/IIA single circlip type sleeve gear)
Another gearbox question


Another gearbox question


Another gearbox question
 
Last edited:
Many thanks for the measurements LAB. Ludwig, can you tell me where you get bushings with oil grooves in them? This probably happened because it looks like it may be hard for oil to get into the outer edges of the sleeve gear? There was slight evidence of the main gear turning in its seat. That and the outer bush moving around probably loosened the bearing.

Thanks everyone.

Dave
69S
 
Thanks ludwig, I guess I could cut a groove in mine with a dremel tool, I might try that. I think we have beaten this one to the end. If you look at the oil grooves in some of the gears, they look like they were cut in by someone with a dentists drill.

Thanks for all the help everyone. I'm happy.

Dave
69S
 
L.A.B. said:
There's some useful advice given in the NOC Service Notes:

"Sleeve gear bushes are always coming loose-sometimes the outer bush moves inwards to the centre of
the sleeve gear-then all you need do is to Loctite a new bush in the end. Leave the old one in and it will
prevent the new one moving inwards, i.e. fit three bushes in your 750 a la 850. Sometimes the bush
moves outwards and gradually mills itself away on the sharp edges of the circlip which locates the clutch.
That’s worse because eventually the bush disappears completely and all the pull of the back chain comes
on the sleeve gear bearing. No wonder the bearings come loose. Often the first sign of sleeve gear
bushes going -is striking "gold" in gearbox or primary drive oil, watch it! Here the answer is to buy two
new bushes and a clutch location shim (060894 or 060895). Push both bushes-Loctited on the outside--
into the sleeve gear--the middle one stops the outer from moving in-and then put the shim loose on the
shaft to avoid the bush wearing on the circlip even if it does move. It is an advantage to grind the outer
edge of the shim so it will pass through the hole in the primary case (or file or even clip it away with tinsnips
to about half the radial thickness)."
Click to expand...

I think I put three in mine, no circlip. Should I take it back apart and locktite the bushes in? I can't remember how loose they were.
 
Dave,
If your original ones were damaged, I would consider re-doing it. If not, I would think about it every time I rode it. I think the washer idea is real good too.

Sorry I had to say that.

Dave
69S
 
DogT said:
Dave,
If your original ones were damaged, I would consider re-doing it. If not, I would think about it every time I rode it. I think the washer idea is real good too.

Sorry I had to say that.

Dave
69S
Click to expand...

They weren't damaged. And I had to use a drift to install them.
 
Dave,
I had to drift mine out, they were that tight. What did you use for a drift to get them in that didn't beat up the ends or did you make one up? I was thinking about pressing them in like Mick suggests with a vice or clamp somehow.

Dave
69S
 
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