AJS & Matchless Owners Club

I've found an extra spacer behind the engine sprocket on my '53 G9. The required 9/32 spacer is there, this extra spacer is obviously not standard as it is too big for the shaft and is about 3.5mm thick. I can't see what difference it makes apart from moving the engine sprocket closer to the shock absorber ramps on start up. Is it some how making up for wear? Has anybody else come across this 'modification' and can tell me how it works, and if it does I'll get a washer that fits, otherwise I'll bin it.

If you remove it will the primary chain run true with the clutch sprocket? Did it run true when it was fitted?
Maybe it was a (misguided) attempt to increase the force of a weak or incorrect shock absorber spring or to align the chain with an incorrectly assembled clutch?
(But I know almost nothing about twins).

Thanks for the reply Spriddler. I checked the chain run with a rule and it seems to be in line. The primary case set up of the '53 G9 is the same as my '52 single (but no dynamo chain). I replaced the shocker spring on the single earlier this year but I can remember if the engine sprocket is tight against the ramps i.e. no movement in and out on the shaft. Do you know how it should normally sit?

If I understand your point correctly, then yes all parts should fit tightly together without any movement in or out once the end nut on the shaft has been tightened. In fact some force is usually needed to compress the spring a bit in order to start the nut on the shaft.

Maybe your extra spacer with the oversize i.d. which is 'too big for the shaft' was intended to increase spring pressure. In which case it would e better fitted between the spring and the dished washer pt. no. 018121 as in that position it wouldn't affect the chain run. (EDIT - Although on second thoughts the extra spacer in that position would prevent the dished washer 018121 from doing its job of keeping the spring centralised around the shaft).

The assembly in the spares list for a '53 G9 is on page 16 here:

http://archives.jampot.dk/book/Spares_l ... s_List.pdf

It probably doesn't help but here's rather poor shot of the assy on a '52 Model 20 (G9)

I think there is too much in and out movement movement of the sprocket on the shaft and I agree a spacer between the dished washer and the spring makes more sense and the thickness would only need to be about 2 or 3mm to tighten everything up and I don't think that will interfere with the job of the dished washer centralising the spring. I'll give that a try and look around for a new spring.

Trefor wrote: ↑Sat Aug 14, 2021 11:30 am I think there is too much in and out movement movement of the sprocket on the shaft

There shouldn't be any 'free' in and out movement of the sprocket on the shaft. When the outer nut on the s/a assembly is tightened it should compress and pre-load the spring.
It seems as you say you have the wrong spring or a weak or even a part broken spring. Unfortunately I don't have access to one at the moment to measure its free length.

Placing a 3mm washer under the dished washer has that exact effect of removing play and pre-loading the spring. As a previous owner has used a four plate from a 350cc single, its possible the spring maybe from the same source. I'll use the washer until I can get a new correct spring. Thanks for your advice.