Rigid Frame Measurements (Petrol Tank Mounting)

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g80csp11
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Joined: Mon Jan 01, 1990 12:00 am
Location: WEST SUSSEX UK

Re: Rigid Frame Measurements (Petrol Tank Mounting)

Post by g80csp11 »

The layshaft on the 46 G80L (CP grease filled box) is part No 30-C-9 and measures 6.3/16 " , where as the part number for 1948 CP oil filled box is 30-C-11

if the spare boxes that I have are actually correct for that year the lay shaft is 5.1/2" long and look very similar

Im sure there are more learned members who know part numbers and the difference much better than me
I know my 46 inside and out , having had it for 40 years

Perhaps Rob knows the difference ?
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Rob Harknett
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Location: ESSEX UK

Re: Rigid Frame Measurements (Petrol Tank Mounting)

Post by Rob Harknett »

I'll pass on gear boxes, never done much more than have an end cover off to rep/ace a kick starter spring. Only thing I may add, just in case its not been considered is. Burman parts kept the same part number. Unlike AMC pt. no's, with old parts still in use circa 1951, being given new part numbers. Also, the AMC model year was Sept 1st to Aug 31st. Burman model year Jan 1st to Dec 31st. So lets say in late 1953, AMC 1954 models will become available. The Burman gearbox fitted may date as 1953 model. Burman boxes had a number from which you can tell the model the box fitted, also year and month of manufacture. This dating info and parts lists found where you usually look.
g80csp11
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Posts: 1567
Joined: Mon Jan 01, 1990 12:00 am
Location: WEST SUSSEX UK

Re: Rigid Frame Measurements (Petrol Tank Mounting)

Post by g80csp11 »

Burman W/NG Army. 1941 to 1945 'cp' gearbox has the shorter layshaft . learn something every day
also has a bush fitted an no rollers on the end of the selector shaft
most of the other parts are the same .

So I guess some 46 bikes could have wng type other the later one
my spare boxes are the W/NG Army. 1941 to 1945 type , but still a good source for parts
Dixter
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Joined: Mon Oct 02, 2017 8:27 pm
Location: Seattle area, WA USA

Re: Rigid Frame Measurements (Petrol Tank Mounting)

Post by Dixter »

Thank you Peter.

I love this hobby!
Ciao, DC
Dick Casey
The RideNut
Peter Wright
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Joined: Mon Jan 01, 1990 12:00 am
Location: NEW ZEALAND

Re: Rigid Frame Measurements (Petrol Tank Mounting)

Post by Peter Wright »

The visual difference in the CP layshafts at the change from grease to oil is that the 1948 shaft was fitted with fixed bronze bushes for the two rotating gears, whereas the earlier type was plain steel.

As far as I know these were all the same length and fully interchangeable but since someone has mentioned different lengths I would need to confirm for sure from my stock. I certainly see no reason for them to be different and ALL the layshaft gears remained the same.

The part to be careful with is the mainshaft. The mainshaft 3rd gear (right side) was given a bronze bush, which has a flange. This required the spline on the shaft to be shortened and the sliding gear to be undercut to clear the flange. The sliding gear can be interchanged, but not the shaft and gear except as a pair (for obvious reasons).

Cheers,
Peter
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