Primary Chain Alignment 37/12

Information relating to Matchless and AJS Models built prior to 1939
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PaulS
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Primary Chain Alignment 37/12

Post by PaulS »

Having problems with chain alignment on the primary drive. Approx 1/8" out of alignment.

Not sure if my engine sprocket spacer is the correct width, it is approx. 5/16" . Does anyone know if this is too wide or can someone confirm the correct width the spacer should be? The spacer part number is STD 630

Any ideas where else to look if this is not the problem?
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Rob Harknett
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Re: Primary Chain Alignment 37/12

Post by Rob Harknett »

STD630 was not a part that continued past the prewar era. It seems to have been introduced in 1937 to 1940 for AJS only, on 250/350 cc machines.
Question mark over 1936 when no AJS parts list were issued. IF ANYONE HAS ANY AJS 1936 PARTS LISTS, PLEASE LET ME KNOW.
I have checked the spares box for my 35/38 AJS bikes and find the following on my spare engine shaft drive assembly.
I find Spacer collar 1 3/16" outside dia. 7/8" inside dia 3/16" thickness. This would make the spacer collar you have 1/8" too thick. If the 3/16" collar would correct your chain alignment, then problem solved. Like wise dynamo chain alignment which you may not had discovered yet.?? If the dimensions I have given look good, perhaps you could get a collar turned up or reduce the thickness of the one you have to 3/16".
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Rob Harknett
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Re: Primary Chain Alignment 37/12

Post by Rob Harknett »

Ashampoo_Snap_2015.09.06_14h48m53s_001_.png
Do not pay too much attention to old 1935 artwork I used here.
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Last edited by Rob Harknett on Sun Sep 06, 2015 4:42 pm, edited 1 time in total.
PaulS
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Location: OXON UK

Re: Primary Chain Alignment 37/12

Post by PaulS »

Thanks Rob, I will check the dynamo spacing and make up a new spacer .
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Rob Harknett
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Re: Primary Chain Alignment 37/12

Post by Rob Harknett »

If the dynamo chain is also out of alignment, by the same amount as the primary chain, then it is the spacer that's wrong.
I found a 2nd 3/16" thick spare spacer, I do not think I will ever need two spares.
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Rob Harknett
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Re: Primary Chain Alignment 37/12

Post by Rob Harknett »

Just to let those interested know the outcome. I found a spare correct sprocket spacer described above. When fitted, primary & dynamo chains lined up OK.
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