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Norton Gearbox Fitted to Comet

davidd

Well Known and Active Forum Website User
VOC Member
For those that are interested in various ways to mount the Norton gearbox here is one way. It is on a racer, so the inner primary is a simple 1/4" plate. The F106 has its legs sawed off. Although this particular set-up has some modifications, I think it would work with a stock primary cover. When you make your own plates you can modify the relative positions of the gear box, the engine and the swing arm, which was done here.
Norton Box _PB_8.jpg
Norton Box _PB_1.jpg
Norton Box _PB_5.jpg


David
 

davidd

Well Known and Active Forum Website User
VOC Member
tidy job.
is 'simple 1/4" plate', dural plate?

The plate is 6061. I have a piece of 7075 that I planned to use for the next racer. I have had not problems with it and one might suspect that it does not have the stiffness of the stock inner primary, but I have not found any decrease in handling caused by lack of stiffness. It is narrow compared to stock and with 18" wheels the added cornering clearance is necessary at full bump. Here is the primary shot of the plate:
Norton Box _PB_15.jpg

The three primary cover holes are marked "cover" and the "No" is short for Norton. I was using a crank-fired ignition so the two mounting holes for the pick-up and the hole for wires is in the center of the. The reluctor was held on by the mainshaft nut and it extended out and across the pully where it just stood proud of the pully so the pick-up could swipe it. The front hole has clearance for the oil seal housing. I think I would make the hole for the counter shaft smaller as it never seems big enough for the sprockets I use to slip through. It is pretty much the same work to take the box out from the other side and the smaller hole might help with strength. The lower most hole is the one that would be slotted slightly for some belt adjustment. This one is fixed.

David

David
 

Kansas Bad Man

Well Known and Active Forum Website User
Non-VOC Member
I like what your doing, nice work that looks like will work. In Wichita there is a salvage yard with tons and tons of aluminum, the trick is to identify what it is, 7075 T6 or ??? . A lot of guess work has went on in the shop, you can usually tell the good stuff by the way it machines.

Go gettem David MAX
 

davidd

Well Known and Active Forum Website User
VOC Member
Below are photos of the more traditional way to mount a Norton Box:
005.JPG
005.JPG
006.JPG
011.JPG

As you can see, the stock inner primary is used, but the hole for the lower transmission bolt must go through the rearward core hole (you can see the original hole just peeking in front of the hole used. The large front core hole is not used.) Also, the F102 is not used and there are two spacers in its place (the front one is obscured slightly by the wood support block.)

Below, you can see the new hole in the inner primary cover behind the stock hole.
013.JPG


David
 

nkt267

Well Known and Active Forum Website User
VOC Member
I have a hard copy of the instructions for this conversion if any body wants it Emailed..John
 

davidd

Well Known and Active Forum Website User
VOC Member
I think this is correct. Norton boxes have a prefix of "N" or "NA." Matchless boxes have a prefix of "M" or "MA." I believe the single prefixes were used post 1957 and the "A" was added to both after AMC bought Norton around 1962. All this to say that the first example of the racer is an N or NA box and the second is an M or MA box. The owner of the second bike says it is an "M." So, the post covers boxes with two different mounts.

The Commando shaft is much longer and I needed the longer shaft to mount the Newby clutch. So, if you plan to go to belt drive it might be easier to stick to the Commando box.

David
 
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