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Norton Box Layshaft Gear

brian gains

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VOC Member
Reading the thread in the technical section with regard replacing the Comet Burman box with Norton box. I have one question which I didn't want to hi jack the thread with.
There are numerous mentions of the Norton layshaft gear roller bearing self destructing and therefore prudent to replace with a bush. Is this a well known/standard mod'when fitting to a big twin. I like to think my chopped motor hasn't got this far without the mod being carried out but am slightly twitched none the less.
 

erik

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VOC Member
I ride my commando since 34 years and my experience is that the original gearbox case is weak where the two bearings of main- and layshaft come close together. i replaced the case by a quaife case which is much stronger in this area.Any movement of the bearing in the case will destroy it sooner or later.Regards Erik
 

brian gains

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VOC Member
so it is a well known weakness and it would be reasonable to expect this to be addressed by knowledgeable Vincenteers when adapting the box to a big twin.
 

Chris Launders

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VOC Member
I would expect so, I have been fitting them for 30 years to any I've built/rebuilt for myself and others, that must be around twenty.
 

davidd

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VOC Member
I think it is a problem that is well-known in Norton circles, but not in Vincent circles. I certainly would use high-quality bearings. It was the brass cage that seemed to break in the originals.

I have only used the Commando box on a racer and then for only a few races as it is illegal. Having installed the TTI box, which is far superior and legal, I never looked back. The original Commando box in the racer was built by John Renwick, whom I would believe, knew how to properly build the box. He is the only person I know that has run a Commando box on a twin. That bike won at least two national championships.

MickyCarter Buller Renwick01.jpg

Chris uses the roller and others, like Mick Hemmings, are partial to the steel and phenolic caged special ball bearing. Both seem to produce good results.

David
 

Chris Launders

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VOC Member
I've had a Norton box/Commando clutch in the Norvin for 20 years, no problems, that's a twin running 34mm Mikuni's and MK2 cams.
 

Glenliman

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VOC Member
so it is a well known weakness and it would be reasonable to expect this to be addressed by knowledgeable Vincenteers when adapting the box to a big twin.
I wouldn't count on Vincenteers or Nortoneers knowing about this problem.
Every now and then, on the Norton forum, an owner will post up about a lockup or ask why the kickstart is banging into their leg.
Some have been riding for years but aren't aware of the issue.


Glen
 

brian gains

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VOC Member
David: if John Renwick puts them together that way i'm in the clear, or at the very least have a high degree of confidence.
ps that machine looks the dogs wots nots, any more photos, spec', utube clips available on line?
 
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davidd

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VOC Member
575 MPH has a photo of the twin and the single when Vic Buller owned it. I think the photo above is when Mickey Carter had it.

Unfortunately, Vic discovered a crack in the twin case that started at the oil filter, traveled by the main bearing and continued toward the clutch. I hope the bikes are still around as they are are the real deal.

Graham Buller on the single:

Graham Buller Mallory 1993.jpg

David
 

Attachments

vibrac

Well Known and Active Website User
VOC Member
As I recall the Buller racer gearbox was legal for BHR because they could prove it was fitted 'back in the day' on that machine.
We were all mates back then and we all ran close to the rules I know the tank was just a shell as the steering damper came through a slot in the fibre glass at the front!
I still say the 5 foot rule ( if it looks period it's ok). is the best way to run vintage racing.
 

BigEd

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VOC Member
VOC Forum Moderator
A year or so ago I saw and spoke to Graham Buller at a Mallory Park practice day. He told me that dad Vic had passed. Graham was still racing and I think he had a Manx Norton in the back of his van. I can't remember if he said they still had a Vincent racer but if he does I don't think it comes out anymore. I used to enjoy my little "chats" with Vic when I was involved with vintage racing. He was usually asking me to OK something or other when he was getting flak about his bikes. I was keen to encourage him as his was one of the few Vincent machines still being raced at these meetings.
 

greg brillus

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VOC Member
That picture above of the twin racer is one of my favorites, those pipes hand made from very thin walled tube by John Renwick himself I believe, same as the ones he made for Reg Bolton for his 1250 twin racer. I have held them in my hands and they are very light weight..........I'll see if I can put some pics on here of my latest Vin racer.........Norton framed, TTI box and so on.
 

Bill Thomas

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VOC Member
Graham once asked me if the Big Twins always Vibrated, I said yes, And He seemed happy with that !.
 

greg brillus

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VOC Member
So that seemed to work........Ok TTI box, 6 speed, the shift is wrong for me, that is why all the stupid linkages. However, I will be changing the box for a magnesium 5 speed soon, with the shift pattern the right way.........One up 4 down.......as it should be.........Sorry to alter the thread, I'm just excited to be able to post a picture.......
 

greg brillus

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VOC Member
Dammit........I knew one of you would notice that.......... Actually that pic is a few weeks old now......I'll have to update with some newer ones..........I wanted to start a thread on its build on account of the mods I've done which are not drastic by any means, but still quite a few interesting ones non the same. My main aim was to keep the overall weight down, and I think i have done reasonably well....... I will start a new thread so Eddie doesn't "Fire me"............... o_O
 

davidd

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VOC Member
those pipes hand made from very thin walled tube by John Renwick himself I believe, same as the ones he made for Reg Bolton for his 1250 twin racer.
John had a gent who bent the thin wall pipes by torch. I think something happened, like a divorce, and the pipe bending stopped. Many years later at a sprint, the bender stopped at John's pit and chatted with him. The bending started again!

Greg, Very nice work...and clever!

IMG20200625072128.jpg

David
 

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