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Burman Gearbox

Vic Youel

Well Known and Active Forum Website User
Non-VOC Member
There seems to be very little discussion on Burman gearboxes in MPH or this forum and very little in FYO/KTB/Richardson etc...... I'm too stingy to have purchased ATY yet and try and utilise my failing memory of MPH technical articles which are now getting very scarce and intermittant. I thought I would share (for posterity) some of my recent Burman gearbox practice.

My Comet assembly was coming along well until I hit more problems with the gearbox during the last few days.

After Charlie Cannon's problems in France in 2006 (rescued by a very talanted Comet rider from Germany) when his Burman outer cover worked loose I decided to do a thorough overhaul pending my European planned rides this year on my new machine. I replaced all the studs (per KTB) with threads for the nuts changed to BSF and had a bit of welding done to repair some stripped studes. I also fitted a sealed bearing from Peter Barker. With minimal trouble I reassembled it over the winter.

It joined my beautifully restored engine (carried out by Maughan's on time and on budget) with a cleaned out UFM (thanks Andy) and the front and back wheels.

Chains all nicely adjusted (clutch looks a little wonky though) and I tried changing gear..... it worked ok on the bench but not now. I had repalaced the cracked mezac spring box with a new one from VOCSC after a second hand one from a Matchless spares company proved faulty. I put in the stronger springs from this latter one..... I found they seemed to pop out when changing gear so had to put the old smaller gauge ones (rather knackered as well) back...... what a palava putting the spring mechanism back ......grovelling a round on the floor (must invest in a stand one day)..... grease all over the place and no Vintech Wellseal this time!

Then I found the nut, just behind the selector knurled axle, loose..... anyone know what this does (it is unclear from the drawings)??.....anyway I tightened it up and it all works...... I did not want to remove the cover for the umpteenth time!

Has anyone else experienced problems with the selector springs popping out......is there a mod? Cannot find anything in the literature. Thanks in anticipation for any advice.



PS On the plus side I now feel confident I could compete with my old colleague from Germany when assembling a Burman gearbox and kick start spring!!

PPS Oh I forgot to mention that I left out the push rod ball bearing and had to take the cover off again..... more lost grease and oil!! Then the push rod was too short and even the VOCSC push rod is shorter than that specified in KTB..... the VOCSC length appears to be the right one though.... about 1/8 inch shorter.



New Forum Website User
Non-VOC Member
just a try to remember

Hello Vic,

it`s me, Thomas from Col des alpes 2006.
I see you hate it is as well to fight with the burman gearbox` unmaintainability and grease and confusing paperwork.

I remember :confused: that in my gearbox the spring case is covered both sides with a thin metal sheet ( approx. 1mm thickness) with the same conture as the casting. So the springs are unable to come out of the spring case sideways. I never had seen such sheets on a burman drawing or parts list. But I think, it`s a good idea. Only have a look , if there is enough space for this sheets.

I did not understand, which loose nut you described. Is this the one, which helds the sector plate, the actuator of the cam spindle ?
Anyway, you got it fixed.

Good luck in finishing your Comet. See you and Charlie at the "Col des massif central 2008". Jean Marie will have once again very good routes for us and enough red wine and very good meals.

Last weekend I tried to find the reason for bad vibrations from the gear train of my Comet.
The reason was the big idler ( a steel one with cast iron centre) with a non parallel centrehole with the teeth direction. A lot of pitting at only the sides of the teeth because of the tumbling pinion when mashing incorrect with the other pinions after only 5000 miles. So I learned another lesson - never use Vincent spare parts without income inspection.

Best Regards

Don Morris

Active Forum Website User
VOC Member
It has been a long time since I had a Comet, but from memory it was similar to my pre-war box. This has one only thin sheet steel plate fitted outboard of the Mazak spring box. As suggested by Ichy 500. This makes it impossible for the springs to shift outwards.

In one Burman spares list I have it is numbered CO55, it fits onto the outside of the spring box with one large hole for the operating shaft and one elongated slot, on an arc, for the operating peg.

Inboard of the Mazak spring box the mechanism gubbins prevents the springs moving out.

Hope this helps, as said, Burman references are thin on the ground as regard Vincent books. That said it is a very simple and sturdy box with not many surprises.

Vic Youel

Well Known and Active Forum Website User
Non-VOC Member
Good morning Don and Thomas, and thanks for your responses.

Mine has one metal plate on the outside. The springs are partly retained inboard by the "gubbins" as Don said but my springs were still managing to squeeze out. I will order some more springs from the VOCS and have another go..... I just don't trust it right now.

A second plate on the inside seems a good idea but how can it be retained?

What a pleasure to hear from you Thomas..... Maughan's said the big idler on my Comet (E50/2) was of very poor quality and discarded it.

See you in France Thomas for "Les Cols" ....... unfortunately Charlie's Comet is in bits.



Well Known and Active Forum Website User
VOC Member
Comet gearbox.

Hi Vic. One of the things we have learnt is to lay the bike over to the left side, perhaps held by a friend, and put in the grease/oil mixture. We than block the bottom drain holes with heavy grease and hey presto the contents stay in place. Hope this helps for the next time.

Len Matthews

Well Known and Active Forum Website User
VOC Member
A Burman box that I was asked to repair had it's layshaft bushes replaced with phosphor bronze-big mistake with a grease filled box, The stub ends of the layshaft had worn right through these bushes into alloy case. The only solution was strip the box completely, temporarily replace the inner cover and line-ream the bush housings and turn up steel sleeves to return to standard.
The proper material for grease lubrication is Oilite; P.B. would be OK if using oil. There is some useful gen on Burman boxes in the current Scandinavian
Vincent Club journal

Vic Youel

Well Known and Active Forum Website User
Non-VOC Member
Scandanavian Vincent Club Journal

Good morning Len and Deejay,

More excellent tips.......any ideas on how the Scandanavian Burman information can be made available to fellow enthusiasts? Do they have a web site/email contact?


PS Read somewhere that the oil to use (SAE90) is available in Halfords and should be to GL4 standard and not GL5 because the latter can damage phosphor bronze.



Well Known and Active Forum Website User
VOC Member
Read somewhere that the oil to use (SAE90)
I went onto the Panther site.The oil they tend to use is 140 grade..I'm using Morris 140 grade straightcut gear oil,it's like treacle in the cold weather but lubricates the box well.Others suggest semi-liquid grease.John


Burman gearbox info

Hello Men, I have a 1951 Burman gearbox booklet which has exploded drawings and text describing most of their boxes, including the BA. As I am not a Comet owner, I'm not sure if this is similar to a BAP box. I have a good quality photocopy which can be used for copying or scanning if someone wants to do this. I am not sure if I am going to get to the Ace, so it will have to be posted or collected. Cheers, ET43

Don Morris

Active Forum Website User
VOC Member
With reference to Len's comment about layshaft bushes, I'm interested in what type of grease was used. Was it the old type of stiff grease Len? or was it the semi-fluid Castrol grease, as advertised in MPH?

I am going to try another make of semi-fluid grease, it's an O grade with EP additive and a 'tacky' additive, seems a little runnier that the Castrol. It's main purpose is for agricultural power harrows, and it is a lovely red!

I've seen a Burman box with just used dirty grease aroung the gears and the rest of the box full of clean unused grease, it was far too stiff.
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