E: Engine Fitting a Norton Gearbox

stumpy lord

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HI,
does any body have any photos , sketches, drawings of fittings, for fitting a Norton gear box to a comet. I have the instructions for fitting the gear box as published in M.P.H. and I was wondering if there any snags to over come .
many thanks,
stumpy lord
 

davidd

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David
 

Jez Nemeth

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Followed the excellent instructions myself, all sets up nicely -thank you David. A few things I've found though, and all are gearbox dependent (and am still fine tuning) - knowing which Norton box you have, Atlas/Commando/AMC? Really helps avoid some issues of Cable/gearbox sprocket alignment, there is a lot of mix and match with them, which is a positive.
 
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davidd

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Jez,

Thanks! I have most often fitted the Norton Commando box and that is the box pictured in my post.

David
 

Jez Nemeth

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I was sold what I believe to be an early Atlas box as a Commando box, so just needed a few mods changing when I rebuilt the box, all parts interchange directly, Commando mainshaft (longer), and cable boss moving and retapping. Clutch fits fine now too as a result, all came together really well following those instructions.
 

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Monkeypants

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Within the Commando models there were quite a number of mostly small changes to the gearbox. The biggest change was with the MK3 850 model. The trans cases were strengthened, shifting moved to left side and improvements were made internally.
One thing that was not an improvement was the made in Portugal layshaft ball bearing in the MK3 box. The layshaft bearing was often problematic on the earlier versions of the Commando box and even more so with the Mk3.
Most Commando owners change out the layshaft ball bearing for a roller bearing, just to avoid the dreaded gearbox lockup.
RGM has the uprated layshaft bearing as do all of the Norton parts suppliers.
If the kickstart drops down on hard acceleration in 1st gear, ride home slowly and take the trans apart!

Glen
 
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davidd

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Glen,

Excellent summary!

Also, I think the longer Commando Mainshaft is a must. Jez, a very nice job!

David
 

erik

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Don`t Forget the power Output of a commando in relation with a Comet.In the Comet the gearbox has an easier life and the shafts and bearings are a minor Problem.Erik
 

Black Flash

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If you are using a commando box with a standard clutch[not diaphragm] change the little clutch operating lever under the cover. The old clutches need lesser lift und using the clutch will be a lot lighter. Also as parts are likely to be mixed after so many years, look out for a box where the kickstart spring is held on with a hook on a post in the inner cover.
Stay away from cheap reproduction kickstarts they are not worth the money and ruin the splines of a good kickstart shaft. Also change the little ratched tang fitted to the kickstart shaft for a new one to give you peace of mind.
If you intend to use rear sets do not use the opposite direction camplate and just reverse the kickstart. If you want the kickstart in a comfortable position you always engage first gear when kicking the bike. This happens when you fit a commando kicker to clear the exhaust pipe and silencer, not sure about a 88,99 or Atlas kickstart.
Just my five pennies worth
Bernd
 

Jez Nemeth

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Good to know Bernd, was thinking about both methods -rear sets and reversing camplate, or rod/to rear gear change off rear footplate, reversed the thing when I did it just in case at the time.

One other decision with the Norton box of whatever flavour you have is the oil feed pipes -to try to follow the original routing, or under the gearbox coming up just in front of the RFM pivot under the battery tray and connecting to the UFM oil tank that way. I tried to keep it original, but found two issues -I needed to cut the feed pipe a little shorter (level with the inspection cover in photo), then tucked under the decompression cable (gets tight at that point and I'm thinking of making a tab to hold the oil pipe off the decompression cable), then threaded through the gap between F106 body and the bolt through the 'new G50', adjusters/top of the Norton gearbox flange, ain't pretty, but it's out of sight and a little protected -if seen in conjunction with David's instructions the second photo should make sense-

Alternatively, could just run it up between engine gearbox as normal, trim pipe, tuck behind G50 and up around F106 to the oil connector, much easier- I just wanted the pipes hidden away where possible...
 

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