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Norton AMC clutch and gearbox guide (questions and answers needed)

As the years go on, information fades away. There's the internet, of course, and it's great resource, but also a great pollutor with fact, opinion and fiction woven into each other. I know history is supposed to be the lie everybody agrees upon, but one can always try to do better. So what I'm trying to do is gather information, put it together and make something resembling the definite guide on Norton AMC clutches and gearboxes. I'm doing the same for Roadholder forks on my website (https://surrogatemanx.wordpress.com/roadholders/). When I'm done, I reckon it would make a good feature in the Roadholder magazine and can also be put on this website for future reference.

I've gathered a lot of information from this forum (far from complete however), but one thing that has me searching for more information, was the mentioning by someone of the fact (fact?) that there were different clutch centres that would sit differently on the gearbox shafts to accommodate for primary chain alignment. If that's true, which models are different and how can one spot the difference?

It's just one of the questions that need answering. I've heard there are 4 or 6 different layshafts/mainshafts, different sets of gears and even gears with the same dimensons, but a different amount of teeth, due to a clever change in teeth shape.

Any other input is welcome too. Most preferably backed up with something of proof (photos, pictures, drawings, scans?). I would like to incorporate these in the final result with your permission.

So, in short, I need two things:
1. Questions to be answered
2. Answers to those questions
3. Measurements and photos. Lots of them!

Regarding the latter. To measure is to know and one photo could say more than a thousand words. I've added some examples below. Regarding measurements: be as complete as possible.

I'm not a UK resident, so most of what I can do is online or by phone. However, if we all work together, I'll do what I can to put it all together in a clear and sensible way that should resemble something of a definite guide. That's why I kindly ask to only post information of which you're 100% sure that it could be published for future reference. And by published, I mean published for free. I couldn't write a guide with the help from others and put it for sale. It's a team effort for the club.

Thanks in advance!

Tim

 

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"which models are different and how can one spot the difference?"

Clutch centres that are interchangeable will have the same part numbers. 

A look at the parts lists for the various Norton models will tell you which clutch centres go with which model. 

​​​​​​" Spotting" the difference can be very very difficult as anyone trying to spot bargains at an auto jumble will attest. 

Hoping your efforts will reveal all. 

Peter

 

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I found he's mainly doing autojumbles, which makes contactinformatie him a bit difficult as I'm based in the Netherlands.

Any contact details (through private message of course) would be greatly appreciated. I do really want to try and produce something useful for future reference.

Regarding the parts lists, they're a good idea Peter, but I don't know if I can trust them. If I recall correctly, sometimes the same parts ended up with different numbers. Maybe there was a difference in material or hardening, but not in dimensioning. Just numbers wouldn't tell me the difference either. Again, it's a very good idea, but not conclusive enough for me.

Cheers,

Tim

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The primary chain alignment is determined by which mainshaft is fitted to the gearbox on early pre-AMC boxes.
The front sprocket offset determines the alignment for AMC boxes.

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From what i have read the earlier whole  Norton clutches and later AMC clutches could be swapped no problem but the parts not , so  its likely dimensionally they are the same . The clutch centers may be the only part that would interchange .

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There is one important difference , the spider in the old Norton clutch has no internal register and relies on a substantial flat washer under the nut to retain the clutch center. The spider fitted to the AMC clutch has an internal register (STOP) and just uses a spring washer, . this difference would (on the same shaft) put the whole clutch further out board . Need to look at the box mainshafts perhaps they were different to accomodate this ?.

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   Once upon a time ,l had an abandoned '55 Dom that has never worked ,and a 1953ish G80 that mostly did, l mounted th pre-AMC Norton clutch onto th Burman g/box. One of th centres had a splined insert (inside&outside) that had to be transferred or deleted, to have th spline fit compatable. l can't remember NOTICING any problem.(Th single now is a 350 with Tri P/U g-box, as th G80's 'box&clutch parts went into someones restoration.) Don't quote me, this may be a dodge that turns up somewhere else. . 

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Helpful comments from you all. Thanks for that. I'll surely use them in my 'definite guide'. Although, I don't know how definite it'll be.

I've called Dave Coates and he was very friendly and helpful, but he said there are so many differences in gearboxes and clutches, that it would be hard to explain by phone. He advised me to take pictures and post them to him by mail. He would have a look at what I've got and then call me to advice.

So, I've made pictures, measured every part and written the measurements down. It has become quite a book.

There's no way to e-mail or do anything digital, which I must say has its own charm. But as I'm based in the Netherlands, it's not an option to just pop around and visit him to make pictures and take notes to put all his knowledge onto paper.

The only thing that I can do, is put everything I hear and read on this forum and in real life onto paper and send it to him to proof read if he wants and correct or add where needed. That, or a local NOC member must be willing to do the legwork. I'm not sure what would be best and have to think about it.

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Hi Tim, 

If you look on the lightweight forum you will see there is much confusion about clutches too. The clutch centres all look very similar and similar to those you have mentioned above. 

Could you please include the three clutch centres designed for Lightweights and their part numbers. The mainshaft spline grew in size
​​​as the lightweights were produced. Small, medium, and large. Up to 1960, up to 1963, up to 1966.

A complete lightweight clutch is easily identified by the duplex sprocket, but after that the important differences lie in the clutch centre. 

Thank you

Peter 

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Peter,

I was unaware of the different lightweight clutch sizes.

Are you able to confirm the different dimensions please.?

It would be invaluable for fleabay and autojumbles !

Thanks, Alan

Hi Alan,

Andy Sochanik answered this question back in April 2020, check the Lightweight forum article "navigator mainshaft and clutch spider". The various sizes are all in there, hope this helps,
Stan

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I've changed the title of this post and added some words to the intro. By doing that, I've made it into something that hopefully should fill with questions and answers during time, as it seems to do already.

I'll then distill that into something resembling a definite guide and try to get some people to do a proof reading.

Sounds like a plan, right? Let's see how far we'll come when we all put our effort in!

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Check out the Dominator Service Notes.
There is a wealth of useful information within the Gearbox section that was contributed by a band of knowledgeable NOC members.

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Good suggestion, there's a lot of info there. I just have to distil the AMC part out of it and I'll be well underway. Cheers.
 

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I've been doing a lot of reading after all your comments and suggestions. I also spoke to Dave Coates, and he explained there are many different variations. Some mix, others won't. I couldn't believe how many different clutch baskets, clutch spiders and so on there are. Same goes for the gearbox. Housings, covers, main shafts, kickstart shafts and gear sets.

There's just so much, and I can't really make a comprehensive guide with just piecing together bits of information from paper. It would be a recipe for errors and if I do this, it must be perfect as it would be something that can be used on this website as a reference.

What would be best is a visit to Dave. He has the knowledge, and he has the parts to show and measure. But I live abroad. So I'm at a bit of an impasse now.

Two options:

1. Somebody close to London joins this project.

2. I take the ferry to Harwich and visit Dave myself. I don't mind investing some of my days off for that, but regretfully I do mind the costs of travel.

 



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