Frame alignment. Gearbox sprocket and rear wheel sprocket

jimbo said:

the sleeve gear bearing could have been installed without it being completely home in the fit.

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Probably not. The guy has been working on bikes and Nortons 25 plus years and actually did the gearbox once before around 1997.

But I do plan to check all these suggestions when I return home in a week thankyou

MichaelB said:

Looks like around 33.5mm on my 72 Combat, 19t.
View attachment 13348 View attachment 13349


https://andover-norton.co.uk/en/shop-drawing/178/rear-wheel-drum-bearings
Part 21 is a washer that fits between the brake backing plate and axle.
In my original parts book it lists the quantity AR. Don't know how thick they are.
Somebody, somewhere knew there was an issue with alignment.

I recently added the thinnest hardware washer I had sitting around .090, to clear the chain guard.
Haven't really taken the time to check what it affected.

Really interested on how all this turns out.
Keeps us informed.

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Just measured mine and it is 33.56 mm

Exactly the same as yours.

So that’s not the issue. Thanks very much for that measurement.

I shall dig further.

Ok. So this has me totally bluffed.

To recap.

the gearbox sprocket is the correct one and is the correct distance from the engine gearbox cradle. (Unless both Micheal’s and my bike are both wrong by the same amount. Very unlikely)

the rear hub brake plate etc are all complete with original components

The cradle cannot be incorrectly positioned in the frame because the swinging arm is fitted to the cradle correctly and in turn the lower shock mounts on the swinging arm are exactly aligned with the upper shock mounts on the frame.

everything measured up fine except the rear sprocket is 4 mm too far to the left with respect the the gearbox sprocket.

Very strange.

Maybe your R. hub bearing retainer circlip is worn and has popped out of it's slot ? Causing drift of rear sprocket positioning. I've seen it before.

The stub axle can be shimmed. Go to the Andover site and pull up the rear drum
Notice part #21. Shim between the axle and backing plate. Shim as required.
Do you have any in place now?
This obviously pushes the wheel to the right.
Spokes can be adjusted accordingly.

MichaelB said:

The stub axle can be shimmed. Go to the Andover site and pull up the rear drum
Notice part #21. Shim between the axle and backing plate. Shim as required.
Do you have any in place now?
This obviously pushes the wheel to the right.
Spokes can be adjusted accordingly.

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This shim would push the wheel over yes. But the place that needs a spacer is between the brake plate and the swinging arm

Torontonian said:

Maybe your R. hub bearing retainer circlip is worn and has popped out of it's slot ? Causing drift of rear sprocket positioning. I've seen it before.

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The circlip checks out ok thank

johnm said:

This shim would push the wheel over yes. But the place that needs a spacer is between the brake plate and the swinging arm

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it moves the sprocket/brake drum over to align the chain. It’s a factory design part for doing this.
It does move the brake drum outward of the shoes,
Need to confirm the shoes are within the drum.

MichaelB said:

it moves the sprocket/brake drum over to align the chain. It’s a factory design part for doing this.
It does move the brake drum outward of the shoes,
Need to confirm the shoes are within the drum.

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With a 4 mm required spacer there is indeed a large gap between the brake plate and drum. The shoes are clearly visible through this gap.

I have put a 4 mm spacer between the brake plate and the swinging arm and everything is now aligned. I will report back on how the bike handles.

johnm said:

With a 4 mm required spacer there is indeed a large gap between the brake plate and drum. The shoes are clearly visible through this gap.

I have put a 4 mm spacer between the brake plate and the swinging arm and everything is now aligned. I will report back on how the bike handles.

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If you've moved the whole brake and hub assembly over by 4mm won't you now need to move the rim back over on the hub by the same 4mm to keep it in line with the front one? Or am I missing something (entirely possible).

bsaboss said:

If you've moved the whole brake and hub assembly over by 4mm won't you now need to move the rim back over on the hub by the same 4mm to keep it in line with the front one? Or am I missing something (entirely possible).

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Yes that is correct. I adjusted the spokes to bring the rim over 4 mm.