Touring on a VB

[dave.pitt]

Rob, sorry I've not replied sooner... I agree with Mike Nash about keeping the exhaust port cool. Mine was full of rusty crap for the first few years I had it. I use a 23 engine sprocket too. I find a VB good for commuting into a city (in my case Birmingham) which I did 5 days a week 1996 - 2006. Pottering around the lanes. But for touring I want a bit more oomph! The BA gearbox - I've got mine in bits now. Last time was 18 years ago, but the same problem. The driving gear, to which the gearbox sprocket is fixed, also known as the sleeve gear, or simply 4th, has 2x phosphor-bronze bushes inside through which the main shaft passes taking the drive from the clutch into the gearbox. The bushes are 1.125" long. The sleeve gear is 2.625" long. There is a .475" gap in the middle between the two bushes. The lubrication for BA/CP gearboxes was originally grease, and from 1948 grease/oil. Neither lubricant gets well up these bushes and they can both seize on the main shaft and spin in the sleeve gear. I have used Penrite semi=fluid grease for the last 28,000 miles to try and overcome this. Because the gearbox has no seals around the kick shaft and gear lever and clutch arm the lighter the lubricant the more it leaks out... onto your exhaust! The inner bush has a habit of working inwards along the mainshaft and making friends with the sliding gear, and actually prevents engagement of 4th, or only fine engagement which causes it to jump out of 4th. 18 years ago I glued mine in with Loc-Tite stud and bearing fit, but it's come out again. This time I've used more manly Loc-Tite 603. I'll report back in 18 years... The potentially more serious problem with this bush coming out is that the gear selector for 4th stays in permanent contact with the slip ring in the sliding gear, causing wear (the selector forks are brass in a BA/CP, steel in later GB's) of the fork and wear of the slip ring. The engagement of the sliding gear into 4th is barely a tenth of an inch anyway. Wear reduces it. Silly really, because the engagement could be over a quarter of an inch. Some folk shim the sleeve gear into the gearbox to increase the engagement, with the effect of putting the gearbox sprocket and rear wheel sprocket out of line. You take your chances... The BA has a lovely gear cluster, and chunky cam driven selector mech with chunky forks. The gear change mech is a spring box affair which is poorly made of alloy (monkey metal). There's a pin fixed in this which is supposed to stay put, but the alloy gives and the pin comes loose. The clutch actuating arm outside the gearbox has a little bronze bush on it's pivot. Negligence causes these to wear through, and then rapid wear of the alloy causing an elongated slot. But the real pisser is that if you break a clutch cable when you're out and about, the lever flops down and the little .25 ball bearing that sits between the cap and the push rod falls out and rolls away, never to be seen again, and you my friend are clutchless! The GB gearbox has lighter shafts, smaller bearings, thinner wall bushes, and inferior forks operating on rods, shifted by a revolving cam. But it is oil lubrication so oils those bushes, it has seals around shafts so doesn't leak its lubricant, and has the clutch operation within the box - it can't lose bits if the cable breaks. All this is for starters... I could go on!

[brett.hayhurst]

A wiggly jigger

That is between the nuts on the bike

[brett.hayhurst]

That is very good information Dave. I still have to o/haul my BA and a G31 box and I will print out and see what you are saying here.
Sounds like you have more knowledge to share maybe if you do not mind on what you have done to your gearbox's or have you already done something in our knowledge base ?
I definitely have more to learn instead of just rebuilding it without doing some of these improvements you have found out the hard way by the sounds.
From what I am reading the GB improved the leaks but sacrificed some of the strong points of the earlier boxes.
Is there a box that stood out at all amongst the Burman where you to have only one that you can stop the leaks and not lose all your bearings should a cable break ?
Or are we able to machine/mill in a modern seal and bearing cage ?
Have searched far and wide to find out improvements as I read that many racers instead fitted the Norton Box even though I have been told that Burman made those too ?
Would you be willing to tell us the mods you have done to improve our early boxes please ? Thankyou
Brett

[dave.pitt]

Brett, I haven't done any mods, but I am going to on the BA. I've repaired two BA boxes in the past, and am now doing my own for the second time (after 18 years/28000 miles). I have also overhauled my 1952 GB6 box for my KH and am now doing my spare GB to run in my VB until the mods are done on my BA. So my Burman gearbox experience is limited to these. I tried to imply in my last post that I would choose a GB box over a BA any day as a practical box. OK the shafts are smaller diameter so the ball bearings are smaller, the gear shift mech is similar to most gearboxes with selector rods, whereas the BA has an arguably superior cam design (but much heavier). But the springbox on the BA which together with a geared quadrant rotates the cam is a heap of crap. The point is that the GB is better lubricated and doesn't spill it's lubricant. I reckon a smaller shaft running in bearings bathed in SAE50 liquid is better than larger shafts running in grease/oil. When I took my BA box apart first time the gear cluster came out of the box and left a hard case of grease of a thousand ages packed around the edges of the box almost leaving a 'cast' of where the gears had been. Some of this grease was light brown, some red, some grey and some dark brown. I scraped it all out... The gear cluster was almost dry of lubrication. It is possible to put O rings on the shafts and make a BA oil tight. I'm planning to do this and other mods. But summer is here (?) in the UK. There are rallies to attend. Roads to be ridden. The BA can wait till the winter snows. The GB is going in for now. I'm hungry for some riding.

[dave.pitt]

For those taking an interest in these postings can I also point you to the separate post "BA Gearbox hints and tips"

[john.whiting]

My book lists the same ball bearings for both BA and B52 (GB),including the same odd size metric /imperial bearing for the sleeve gear.The mainshaft is a much bigger dia than Norton /AMC or unit Triumph .The later Ariel box has the advantage of an adaptor to mount the clutch centre,which means replacing the sprocket doesn't require pulling the gearbox apart.Regards John.