Gearbox numbers

Hortons Norton

Hortons Norton

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Hello guys, I purchased a gearbox over the weekend at a bike swap meet, Can anyone tell me what model this was from. The shell is stamped with; N 19480 Thanks, Chuck.
 
Hi.
It depends where are the two lugs to fit the gearbox on the frame and if the upper lug has or not an opening for the primary chain tensioner.
Sure is not a Commando one that has six number and then a letter and the first begin from 123... .
Piero
 
Those numbers should make it an AMC style box, for a Dominator.
(N is for Norton !, and its pre-Commando)

Quite where in the sequence that would be I don't know,
maybe someone has a good handle on the possible varieties.
A pic might help to say if its the Mk 1 or Mk 2 version.
Expect it to be fairly worn, but you might be lucky.
 
The shell looks to be the same as a Commando, I must have some luck on my side. The bearings were nice and tight in their bores and all the threads are perfect. The only thing I can see is wear from the chain being loose and rubbing on the case some, the guy I purchased it from said it was from a Vincent race bike that had its rear case end cut off??????? It had no kick start shaft coming out of the outer cover, looks like it was cut off or maybe made that way? But the shafts and gears look in good shape. I am hoping to use this in my Atlas project, it's not the P11 or other hybrid types of box that much I know. But is there other of types that were like the commando shell??
 
If you compare it side-by-side with a Commando shell, is it absolutely identical ?
All the lumps and bumps and divots and curves.

The Commando ones and even the dommie ones were subtly changed and strengthened
a number of times over the years. Even the 1st dommie one looks approx like a
Commando one, until you compare the exact details of those lumps and bumps...

Even the tooth form inside changed at some point, also the tooth counts, and the clutch mechanism.
And there are solid and sintered versions of the bronze bushes.....
hth
 
"N" Your box marking says it's a early AMC box. N typically is the early style: kicker, kicker spring, and matching inner and outer cover. These "N" parts do not readily interchange with"NA" or commando parts. People have machined them to update them... but a not real necessity.
How ever even my 63 atlas had a "N" and likely was not original for the bike. It could have been changed internally, so you won't know until you open it up.
 
I have two featherbed Nortons. The 1962 ES2 (originally Model 50) has gearbox number NA3298 and the 1964 650SS has gearbox number NA6062.
The are threads on the Norton Owners Club discussing gearbox numbers and it appears the "N" prefix predates the "NA" prefix.
It would seem, from reading the numbers discussion there, that your gearbox is most likely late 50s.
It could be from either a single or twin as both were using AMC gearboxes then
Cheers
Rob
 
I
Have two Featherbed gearboxes 1958 99 Dominator N7798, and 1963 650SS NA2562, both are original to the bikes, although not much left of the 99 :cry:

Burgs
 
From my experience, gearbox numbers were independent of engine/frame numbers until late 1968. My late (July) 1967 G15CS has gearbox NA19019G. The G15/N15 and P11 gearboxes were in the Matchless/AJS pattern of top mounting lug at 12 o'clock and bottom lug at 4 o'clock. Nortons were at 12 o'clock and 6 o'clock.

I would guess that your box is a late 1967/early 1968 Norton box, but I'm sure there's someone out there that can pinpoint your box more precisely.
 
I want to thank all of you for your information, Dave I can see the difference on the inner cover as there is no post for the return spring. It looks like it fits into a hole instead, also the steel bush for the shaft is also much wider. After cleaning and seeing how nice the shell looks, I think this will be the one I use for the Atlas. Thanks again guys you rock, Chuck.
 
I think the boxes changed over to the Commando type kick start return spring in 1963 or 1964. You are correct, in the early box there is a tang on the inner end of the spring that goes into the hole in the inner gearbox cover. The early spring is much smaller and weaker than the later Commando type spring that fits on the post mounted on the inner gearbox cover. I also suspect that some reproductions of the early version spring are made with a shorter tang that fits into the hole in the inner gearbox cover than was original. I believe this explains my personal experience with that end of the spring becoming detached, which can result in a dangerous situation since the kick starter then hangs straight down. Very exciting on right hand corners. DAMHIK. I am not certain, but I believe that you can replace the inner cover on the earlier gearboxes with the later inner cover that has the post for the much improved Commando type return spring. The hole for the inward facing tang on the outer end of the spring (the part that goes into a hole on the kick starter shaft) is much closer to the inner gearbox cover on gearboxes that use the earlier spring. If you do a conversion to the later set up you would need to either use the later kick start shaft or drill a hole in the correct place in the old case hardened kick starter shaft. BTW, temporarily mounting the kick starter upside down on the shaft and using a large screw driver as a lever is an easy way to fit the outer end of the spring that goes into the kick starter shaft. I hope this is helpful.
 
Bodger said:
I think the boxes changed over to the Commando type kick start return spring in 1963 or 1964. You are correct, in the early box there is a tang on the inner end of the spring that goes into the hole in the inner gearbox cover. The early spring is much smaller and weaker than the later Commando type spring that fits on the post mounted on the inner gearbox cover. I also suspect that some reproductions of the early version spring are made with a shorter tang that fits into the hole in the inner gearbox cover than was original. I believe this explains my personal experience with that end of the spring becoming detached, which can result in a dangerous situation since the kick starter then hangs straight down. Very exciting on right hand corners. DAMHIK. I am not certain, but I believe that you can replace the inner cover on the earlier gearboxes with the later inner cover that has the post for the much improved Commando type return spring. The hole for the inward facing tang on the outer end of the spring (the part that goes into a hole on the kick starter shaft) is much closer to the inner gearbox cover on gearboxes that use the earlier spring. If you do a conversion to the later set up you would need to either use the later kick start shaft or drill a hole in the correct place in the old case hardened kick starter shaft. BTW, temporarily mounting the kick starter upside down on the shaft and using a large screw driver as a lever is an easy way to fit the outer end of the spring that goes into the kick starter shaft. I hope this is helpful.
Click to expand...
 
just bought a nos kick starter return spring for my norton n17436 gearbox but still popping out of inner case. is there someone that makes longer spring ends to help hold in place to save gearbox modification that bodger has suggested
 
triton 62 said:
just bought a nos kick starter return spring for my norton n17436 gearbox but still popping out of inner case. is there someone that makes longer spring ends to help hold in place to save gearbox modification that bodger has suggested
Click to expand...
Since your spring is NOS (are you sure?) and therefore presumably the tang is the correct length, I wonder if the hole in the inner case is worn. I have often wondered if this could be repaired by making a "thimble" out of a pop rivet body or equivalent and using JB Weld or equivalent to hold it in place.
 
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