Burman B52 Gearbox help please

[nomisimon]

After a few years of illness, I finally got my old Matchless G3LS back on the road. It's a 1953 G3LS which I bought as a farm bike, back in the mid 1970s...for £8.

Following the departure of my dynamo sprocket from its tapered shaft recently, I've now taken the damaged parts off. The dynamo shaft is bent, the dynamo sprocket has survived but there is an issue with the gearbox.

When the dynamo chain came off, the back wheel almost locked up as the primary chain had also been dislodged and things were jammed. The primary chain was riding on the body of the clutch and up on the teeth of the engine sprocket.

When I got the bike home, on a recovery truck, the primary chain and rear chain were both very tight indeed. I had to lever the primary chain off the sprocket teeth to proceed.

The obvious damage and problems are fixable, but there is an apparent fault with the gearbox for which I'd very much like some advice from someone who knows about these things; I've never dismantled one.
The clutch and housing have been completely removed, just leaving the chain driving the back wheel. In any gear, and neutral if I hold the input splines still, there is a clicking coming from the gearbox when I turn the back wheel either way. There is a similar noise when I press the kickstart by hand in neutral. When the clicking happens, the gear selected indicator moves in and out in sync with the clicking. If I push the gear selected indicator wheel in with my thumb, the clicking stops. It's possible to select all the gears it seems.

Something is awry and I'm hoping someone knows what it is.

Thanks in advance.

[alanengineer]

!st step then, is to take the outer cover off the gearbox and have a look see.
Their are good magazine article in pulling a Burman box apart

[nomisimon]

Yes...indeed. The problem appears to be internal. My hope was that someone here had encountered a similar problem and would suggest the likely cause. The gearbox is halfway out now.

[spookefoote1956]

You'll not know until you crack it open. There's plenty of articles on taking them apart and re-building.

[alanengineer]

almost all jobs can be done with the gearbox shell in place, dont make work for your
self

[nomisimon]

I've actually removed the clutch assembly and all the chains...and the dynamo for refurb. The inner chaincase is off...but I haven't actually removed the gearbox; it looks like unnecessary work, as you say. It looks like the box has been filled with a mix of grease and oil...something I believe was done in earlier gearboxes. It doesn't appear to 'flow' so this could get messy.

[nomisimon]

I can't see anything awry with the outer cover removed...so it must be internal.

I'd appreciate it if someone could let me have a link to a really good article on a strip and rebuild of this gearbox; I've not had one apart before but am happy to learn.

Thanks

[SPRIDDLER]

You are showing as a 'Guest' i.e. a non-subscriber so you can't access the club's own technical archive (and much more) which is funded by subscriptions (as is this excellent helpful Jampot website ) but have a look here where there are a couple of B52 gearbox articles:
http://archives.jampot.dk/technical/Tra ... on/Burman/

If it wasn't for the clicking stopping when you press on the gear indicator I'd have suspected that the shock of the lockup may have chipped or broken a tooth on a cog, causing a clicking sound.

[nomisimon]

Thanks Spriddler...I was a member for a number of years but let it lapse due to illness. I will be rejoining; it would be rude not too

I'm gutted that this has happened to the bike as it was running and riding beautifully. I had a sensation when riding that a brake was being applied for a few seconds, then let go. It happened a few times so I pulled over. Nothing obvious seemed wrong and no symptoms at lower revs. I turned round and headed home slowly...about 4 miles away. About 3 miles from home there was a horrid crunching noise and the back wheel almost locked up. Instinct is to pull in the clutch and pull over...I did but quickly stopped the engine. Since my last post I've been taking a good look...I think there may well be some gear damage but will need to strip out and check / rebuild the box. It will be messy as the gearbox is filled with a grease / oil mix rather than just oil; my reading suggests that was only done with earlier boxes than the B52?

When I was first ill, over 15 years ago, my cousin did some work rebuilding the bike. It turns out he didn't fit the Woodruff key on the dynamo sprocket taper, nor did he fit the special nut assembly to hold the sprocket on...choosing instead to rely on a split lock washer and standard nut. Total madness...these safety devices are there for a reason.

I suspect an intermittent short in the dynamo armature was causing a braking effect on the engine...eventually the dynamo sprocket broke free.

I've already had the magneto fully refurbished and will be sending the dynamo away also. The parts are available and I could probably do it myself...except for the pole shoe expander.

[clive]

I doubt a short in the Dynamo would produce the symptoms of braking when travelling at speed.