Burman, Type H gearbox. AJS 38/26

[trophy]

To investigate the reason for my gear lever occasionally failing to return after an up/down change I have got the gearbox on the bench. I have worked on a few different Burman gearboxes but this model H, with its clutch operating arm enclosed in the end cover is a totally different animal. Can anyone advise where I can get any literature/drawings of this type of gearbox, especially showing the gear clusters. All suggestions gratefully received.

[Rob Harknett]

I am wondering just what version of mod H gearbox you have in your 1938 model 26 Silver Star.
There was no model called Silver star. Have you a picture showing the RH side of the bike.
Is your engine no. prefixed 38/26 SS ?

[SPRIDDLER]

At least two technical articles on the Burman model H gearbox in the Archives under: 'Technical' .....'Transmission'..... 'Burman':

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

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

There may be more if you browse the index here:

http://archives.jampot.dk/technical/Tra ... on/Burman/

[Rob Harknett]

There was a new shape box introduced in 1938 for 250 & 350 & 1939 250 only. So need to see what box you have.
Is it oval shape like this ( sorry its a low res pic. ) If it looks like this, I am not aware of any literature for this 38 - 39 type box.
Please share if you have any literature for it. Rob prewar@jampot.com Note this box has kick starter ratchet and gear selectors all enclosed within the outer cover.

AJS 38-26.jpg

[trophy]

Hello Rob. My gearbox is as your photo and is as you describe. On dismantling I noticed the smaller of the 2 gear selector return springs was fitted with the legs crossed and not in parallel. Could be the reason for a floppy gear lever?? Cast markings on the shell:- 1-HP. M. 16-18. 21-22. Stamped markings on top of the inner cover:- 8HPB. 25175. Apologies for the Silver Star bit. It a bog standard 38/26.
Messy box to work on. Is the grease readily available, and how would you go about filling it on completion?

[Greybeard]

I use Penrite semi fluid grease in my grease boxes though there are others such as Spherol which is a bit thicker.
https://www.classic-oils.net/Penrite-Semi-Fluid-Grease
For filling, one of these helps and may be cheaper from other suppliers

As youve discovered, theres no 'clean' way of dealing with a grease filled box Just keep plenty of rags handy - and a large tub of Swarfega

Steve

[Rob Harknett]

I use Penrite semi fluid grease in my grease boxes though there are others such as Spherol which is a bit thicker.
https://www.classic-oils.net/Penrite-Semi-Fluid-Grease
For filling, one of these helps and may be cheaper from other suppliers

As youve discovered, theres no 'clean' way of dealing with a grease filled box Just keep plenty of rags handy - and a large tub of Swarfega

Steve

As Steve states, modern semi fluid grease should be OK. The old bikes are not very fussy. For the old grease filled boxes you will read in manuals, put an egg cup full of
oil in, in particular after standing for a while. This will help loosen up gear change action. The oil will of cause seep out.
http://archives.jampot.dk/technical/Tra ... b_1941.pdf You may get some tips from this article.
http://archives.jampot.dk/technical/Tra ... Models.pdf Compare parts in this parts list.
http://archives.jampot.dk/book/Workshop ... dition.pdf This is the best workshop manual edition to use. note the old artwork used.

1. My 1938 mod 26.jpg

My almost original 38/26. You may not see it has a single port 47 top end fitted.