a10 gearbox sprocket-depth?

[1660bob]

Hi All, noticing a slight alignment problem with A10 my rear chain, i have been inspecting the two gearbox sprockets that i have. The first (worn out)is possibly an original BSA item, and its total width, from front face to the end of the boss that buts up against the gearbox bearing is 15/16". The second is a new item, supplier unknown, and the overall width is one sixteenth less at 7/8", thus altering the chain line slightly. Its not a lot, but i do have misalignment to sort out, and the new sprocket makes things worse.......

Anybody know which sprocket is the right width?  15/16" or 7/8"-come to that, are they both wrong?? Has anybody got a spare gearbox sprocket they can measure for me?
 Thanks in anticipation, Bob.

[chaterlea25]

Hi Bob,
I went and measured a new "pattern" 5/8 x 3/8 sprocket its 15/16in.
A new 5/8 x 1/4 sprocket (Goldie) measures near enough 7/8in.

I seem to have recycled all the old worn sprockets??

HTH
John

[duTch]

 I also measured two old worn out ones, one being an early one with an oil scroll, and they both measure near as damnit to 15/16" (~0.934-0.940)
 On the upside, not ideal but you'll be able to pack the thin one with a spacer shim