Rear engine plates

[Trefor]

I have a 1953 G9 with a CP gearbox fitted. I'm going to fit a GB which is correct for that year. I notice that the rear engine plates for 1950 (CP) and 1953 (GB) are different in the spares lists. My question is how can I tell which engine plates are on my bike- the original 1953 ( the frame number is correct for that year) or the those to suit the older gearbox. I'm wondering if the CP box would fit in the 1953 plates and if there is a way to identify the different plates?

[clive]

According to the parts list the change was in 1951 and unfortunately they never changed the illustration in the parts list but it does suggest the change was not because of the introduction of the GB gearbox (in 1952). On singles I think either fits. Unlikely your engine plates were changed much more likely someone fitted a CP box because it was there and cheaper than trying to repair a GB box. Just to add to the issue the GB box has to have part no G-35-2, mainshaft sleeve, fitted to the drive shaft before the clutch is fitted (page 23 in your parts list). This is not necessary, (nor I think will it fit) with the CP box so it may well be missing. The rest of the clutch should fit whether originally for a CP or GB box. I would be inclined to track down one of these sleeves before beginning your exchange, the club spares list them with no stock at present.

[Trefor]

Thanks Clive. Well spotted with part number change in 1951. I'm collecting GB boxes and bits at the moment and will check for the sleeve you mention.