Burman gearbox screw

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Spanielsam
Posts: 86
Joined: Fri Jul 03, 2015 4:16 pm
Location: LEICS UK

Burman gearbox screw

Post by Spanielsam »

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Hello
I need a bit of advice please
I am trying to stop some of the oil leaks from my 1956 G80S Burman gearbox and have seen other posts on the same topic on here and it looks like it can be a familiar problem ?

A couple of questions please
I have replaced the front cover gasket and used blue hylomar gasket cement and i am still getting a small weep from the botom of the box , i have seen that the correct thing to do would be to get the faces skimmed as there are no obvious marks on the joint faces , but as a lazy fix I just wondered if there was a cork type gasket available rather than the standard paper one ?

Also there is a screw on the back of the box that is leaking and although i have undone it a few turns it still seems tight as if it is attached to something inside the box and inas to avoid the dredded "boing or clunk" if i carry on taking it out, i thought about putting a fibre washer on it ? Any ideas what the screw does ? I have tried to show it in the attached photo, it s on the other side of the gearbox to where the filler cap is

Thanks in advance
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g80csp11
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Re: Burman gearbox screw

Post by g80csp11 »

Page 19 onwards will give you much better idea of what the various parts of the burman gearbox are
http://archives.jampot.dk/book/Spares_l ... ingles.pdf

and the owners handbook
http://archives.jampot.dk/book/Owners_m ... ingles.pdf

http://archives.jampot.dk/technical/Tra ... ebuild.pdf


if the faces are clean on the gearbox and you use the correct gasket wiped with a smear of grease before assembly , it will not leak
the gasket when softened in this way will take up imperfections on the faces
oldandsmelly
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Re: Burman gearbox screw

Post by oldandsmelly »

I have a Burman b52 fitted to my G80 and another 4 boxes in my 'come in handy' stores. None of them have an extra exterior bolt except for the drain plug and the very large observation cap fitted to later boxes, so I'm not sure what this is. A photo of the front of the box would help confirm what type of gearbox it is.

As for the oil leak, I'd confirm first (if you already haven't) that the leak isn't coming from the kickstart spindle or gearchange spindle. The kickstart spindle is a bit of a favourite for leaking oil probably due to the hard life the bush gets. If it is this, the improved bush and oil seal which is hopefully still available from Andrews engineering fixes this like magic.

If the leak is coming from the gasket, then in the first instance I would try Wellseal instead of Hylomar. I find Wellseal will seal just about anything. If the joint faces are too damaged even for Wellseal, then you could try refacing the outer cover. You can do it yourself by mixing some fine grinding paste with oil on a sheet of glass, slate or similar and rubbing with a gentle circular motion. A less messy way is to tape down some fine wet and dry and do the same. The only fiddly do is the peg for the kickstart spring which gets in the way and is a thing I've never managed to remove so you'd need to drill a hole in whatever is being used as a flatbed. However, it's very important not to overdo it. If too much material is taken way, the cam spindle on the B52 box can get locked tight against the bushes when the cover is replaced meaning the gear change is at best very stiff or won't move at all.
Spanielsam
Posts: 86
Joined: Fri Jul 03, 2015 4:16 pm
Location: LEICS UK

Re: Burman gearbox screw

Post by Spanielsam »

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image.jpeg
Hello and thanks for your replies

I cannot see the screw on any of the documents and so i wonder if its a previous owners add on ? It does look quite deliberate with a chromed spacer sleeve under tne head of tne screw

The gearbox looks standard but i am no expert , i have attached a couple of photo's

Also the manual says fit fibre washers under the heads of the front cover screws - is this necessary as the club shop doesnt seem to have them
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ajscomboman
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Re: Burman gearbox screw

Post by ajscomboman »

At a complete guess I'd say the box has been modified around the kickstart stop on the inner cover. It's not unusual to see damage in this area even cracked cases! None of my Burman boxes have this bolt on the inner but I do have a cracked inner to prove that damage at that point is not uncommon. Also those numbers on the box you can forget about, they've been so messed about with they mean nothing. Doesn't effect the operation or the function of the bike or box in any way, only nit-pickers.

The fibre washers under the screw heads are stocked by AMC Classic spares but aren't really necessary. Out of 4 boxes only 1 of mine have them on and they made no difference. Likewise despite flatting the faces and using grease and other compounds on the boxes I still get very minute weeps.
SPRIDDLER
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Location: WEST SUSSEX UK

Re: Burman gearbox screw

Post by SPRIDDLER »

The third link given by 'g80csp11' is for the Burman CP gearbox. (He's probably still suffering post-traumatic stress disorder after shelling out for a new jacket for his ride next week to the Spanish rally on his P11).

You have the Burman GB52 'box. Exploded view in the link below. it doesn't show any screw fitted at the rear of the kickstart housing, probably because there isn't one...

http://archives.jampot.dk/technical/Tra ... d_view.pdf
Last edited by SPRIDDLER on Sat Sep 22, 2018 3:03 pm, edited 1 time in total.
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Andy51
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Re: Burman gearbox screw

Post by Andy51 »

Hi, from your first photo the unexplained screw seems to have been fitted in the back of part G-2-2, Case Kickstarter. I have never seen one there, nor is one listed in any spares list. As AJSComboman says, it appears to be a PO modification - perhaps the kickstater stop got broken and this is a repair? I think you will have to look inside, you can take off the outer cover and k/s cover with the gearbox in situ - you would have to dismantle everything to true up mating faces anyway. Never use any gasket thicker than that originally used. Cork gaskets are quite thick and will change all the end floats, etc. Worse, they could compress unevenly and you could end up with slightly canted G-2-2, which would make operation of gear spindles and thus gear changes difficult, and the misaligned bearings would add friction and cause early wear. Cheers, Andy
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