Burman HP Gearbox

[GuyH]

I'm still looking for a 4 speed Burman HP gearbox for my 1939 250 Model OG restoration. These are the small egg shaped box which were fitted in the 1939 250s and also the 1936-39 AJS Model 12s and apparently late pre war 250 Red Panthers. They were often taken out and put in trials bikes so there could be some lurking in some old trials machines somewhere. If anyone has one for sale please PM me. Does anyone know if a later Burman B52 box would fit?

[nevhunter]

There might be a few CP boxes around, if they will fit The 39 250 frame is the same as all others isn't it?

[brenton.roy]

Hi Nev, I'm not sure that it is.. I think there's a post from John Mitchell about this..
Found it viewtopic.php?f=11&t=944&hilit=+1939+OH
Brenton

[GuyH]

Thanks for the replies. Unfortunately the H/HP box is completely different from the CP. It may be possible to make one fit though. An alternative may be the Burman B52 box but I'd rather find the original HP if I can. I saw John's post a few months ago and got in touch with him and have bought some bits from him for my restoration but unfortunately he lacks both the gearbox and inner and outer chain-cases - parts which I am looking for too. I do have a 250 OH as well with a Hartley engine which has the correct box and cases. I asked around to see how much it would cost to have a couple of sets of cases cast but the cost was akin to the GDP of a small European country! If anyone knows of somewhere which can make castings at a decent price I'll be interested to know.

[brenton.roy]

Hi Guy, can you post a photo of the box you are after? - One of us might be fossiking around a bike wreckers yard...
Re the cases, given these are so rare, someone might be willing to share the cost of creating a CAD drawing for a CNC mill - the club?
The billet wouldn't be cheap though. It wouldn't be hard to find an engineering firm to do the milling.
My local school has a 3D scanner, which produces 3D drawings. It moves a needle point over the shape.
I assume these are also available more or less everywhere. http://www.3dscanners.co.uk/reverse.html
There is a process called "lost wax" casting, for one off's - which might work if you are brave and have access to enough heat.
or... James May http://www.youtube.com/watch?v=1I3P6pmy3P0
Brenton

[nevhunter]

Followed that link Brenton thanks. I know the box is not the same (CP) but I thought that all the frames were "similar" for all capacity bikes after about 1935. Panther or AJS may run the smaller box. Nev

[brenton.roy]

Hi Nev, I was pretty sure my '34LH frame is different to the larger bikes, but now am not so sure.
I need to get two side by side and measure them.
It could be the larger wheels (both 20") that does it. Anyway, that's why I was paying attention to the earlier post.
I was at a wrecker the other day looking for stuff, and found that he didn't really know what a lot of the bits were from. This is the remains of the '70's wreckers collections in SA, so he would have bought it as a heap of boxes / pallets. I imagine this is the same in a lot of places.
Hence, my request for a photo. I don't know what to look for to spot a H/HP box.

BTW - we seem to have lost our nice blokey waxed cotton jackets and now have these silver gizmo's. Not too sure about that... What will our Mr. Nash come up with next?
The fur collar suits me though - particularly since my hair went south. Rain drops used to patter, now they thunk..

[nevhunter]

The earlier 30's bikes were all individual sizes and not much in common. It would have been natural to use as many common parts as possible. Around 1934 there were some real good 250 OHV's around made by many brands .Rudge BSA Ariel Triunph,New Imperial .All nice and light with good performance.
Dunno about the coats. I don't put as many on when I paint anything. Nev

[GuyH]

Thanks to everyone for the help. I like the James May option but can see me dissolving vital parts of myself so thought I'd better not try it! It's actually the same type of casting process as where I got the quotes from to replicate the chain-cases. The bike came with a CP box in a set of home made aluminium gearbox plates but nothing lined up and it was all a bit of a bodge. I guess this means someone in the past was having the same problem as me. The frame I think is a bit smaller that the W/NG but I could be wrong. I think I've uploaded a photo of the HP gearbox in my OH but being an old Luddite I don't get on that well with computers so it may not come out.....

[john.mitchell]

Nev, I think you were right. I had most of one of these once but as it was missing the gearbox and Primary cases I gave up and sold it on. As I remember the only difference on the frame was that the rear wheel mounting point was brought forward a couple of inches exactly as was done on the first VCHs It didn't occur to me then, but I can't see why a CP (or GB) would not fit.