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Broken 7CP Burman Gearbox shell!

radders

Forum Website User
Non-VOC Member
Hi all,

We have managed to break a part of the casting that holds the clutch lever on an early CP gearbox. It is a loop that's part of the case, holding the external lever, which operates the rod that passes through the box to the clutch - It acts as the hinge for the clutch lever (I can e-mail photos, not a very good description!).

The box is fitted to my grandfathers 1927 HRD 90 in place of the top hung original. It is a 4 speed foot change unit that has been on the bike since at least 1946. I have tried every dealer etc. that I can think of (Draganfly, Ron Farthing, ACM etc) for a replacement.

Can anybody help? It is model/number 7 CPBX 19584, a couple of people have suggested that it is an early Ariel box.

Does anybody know what the numbers stand for/what age the box is/ what it's originally from please - this would really help my search! The ally is poor quality and the broken pieces are very small. I don't think it will weld, vacuum soldering has been suggested, has anybody tried this on these old cast ally parts?

Would really appreciate any advice!

Many thanks, Matt
 

Howard

Well Known and Active Forum Website User
VOC Member
Something in the depths of my memory says this might be an AJS/Matchless gearbox you could try their Owners Club/Spares.

Nothing defiite, just a long hunch.

H
 

vibrac

Well Known and Active Forum Website User
VOC Member
CP is a Burman Box (god help us all) and I think Howard is right AJS & Matchless rings a bell.come to the Spares open day all the AJS and Matchless sages will be there... and a few Vincent owners
 

clevtrev

Well Known and Active Forum Website User
VOC Member
Hi all,

We have managed to break a part of the casting that holds the clutch lever on an early CP gearbox. It is a loop that's part of the case, holding the external lever, which operates the rod that passes through the box to the clutch - It acts as the hinge for the clutch lever (I can e-mail photos, not a very good description!).

The box is fitted to my grandfathers 1927 HRD 90 in place of the top hung original. It is a 4 speed foot change unit that has been on the bike since at least 1946. I have tried every dealer etc. that I can think of (Draganfly, Ron Farthing, ACM etc) for a replacement.

Can anybody help? It is model/number 7 CPBX 19584, a couple of people have suggested that it is an early Ariel box.

Does anybody know what the numbers stand for/what age the box is/ what it's originally from please - this would really help my search! The ally is poor quality and the broken pieces are very small. I don't think it will weld, vacuum soldering has been suggested, has anybody tried this on these old cast ally parts?

Would really appreciate any advice!

Many thanks, Matt

Don`t bother even thinking about the bits, just weld up and remake.
 

Tom Gaynor

Well Known and Active Forum Website User
VOC Member
You might try Lumiweld low temperature welding. I never have, but it has had some good reviews.
My Burman book(let) says there are two heavyweight 4-speed boxes, the C and the BA. The implication (it doesn't actually SAY) is that the difference lies in whether the clutch operating arm is inside or outside the outer cover. There is no suggestion that the gearchange mechanism or gearset are different. The booklet does give some drawings showing three variants of clutch mechanism operating on the same box and clutch. Since the BA has it inside and yours is outside, then "C" would seem to be a BAP (i.e. post-war Comet) box, but with an outer cover with clutch operating arm outside.
It would be unusual if Burman made different shells and inner covers for the same gearset having done no more than tidy up the design by moving the clutch lever under cover, so a later cover from a BAP box might fit straight on.
 

Vincent Brake

Well Known and Active Forum Website User
VOC Member
Hi I might yust have the part you need,:) yust arrived 3 outer covers for an early box, plse Email a photo

regards

vincent
 

Comet Rider

Well Known and Active Forum Website User
VOC Member
Parts transport

Hi Matt,
I will be seeing Vincent in a month, at the Dutch (Belgian) rally and could bring it back for you as I live just south of Cambridge

HTH
Neil
 

radders

Forum Website User
Non-VOC Member
Broken Gearbox cover

HRD and B'St_BMW damage 029.jpgHRD and B'St_BMW damage 028.jpgGrandads HRD 012.jpgGrandads HRD 011.jpg

Hi,

The photos of the broken gearbox cover as requested. The first two show the broken lug, the last one shows where the clutch lever attached before it broke.

Many thanks, Matt
 
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