Ariel Owners Motorcycle Club

Paul, You are correct (in my opinion) The combined length of the hardened steel sleeve(bush) and the depth of the splined bit in the ratchet affects the end float. Perhaps there are variations ad the parts get somewhat mixed up. There's no advantage in having end float. The clutch action will push it to a playless condition temporarily, but that uses up lever movement. The clutch throwout mechanism isn't the way to control end float.. Nev

I think I've rebuilt 5-6 BA/CP gearboxes and I cannot remember any of them having the steel sleeve/bush tightened hard up between the inner race and the splined racket gear as Ian suggests. It is possible all my bits were worn out...but I didn't think that at the time, so this morning I've taken a closer look on the bench with some spare parts I have:

The first photo shows the protruding mainstaft in the outer space with the steel sleeve/bush and splined ratchet gear in place and the nut tightened down. For clarity, I've left off the spring and the rotating ratchet gear.



On the other side of the case / mainshaft, I've fitted the correct un-splined gear:



With this current set up, I can easily detect endfloat...I can push the mainshaft in-and-out of the case cover and I can measure it as 21 thou of an inch:



But should there be any? Absolutely! If I simulate removing all endfloat just with my fingers, that un-splinned gear on the other side of the case cover soon locks up and is no longer free to rotate on the mainshaft.

I don't think 21 thou is excessive but it is probably more than Burnam intended as my steel sleeve does show some signs of wear, as does the underside of the splined ratchet gear and the face of the inner race...plus the two faces of the unsplined gear on the other side of the mainshaft.

Hi Paul,
In the W/NG manual it states: "The mainshaft should have 1/64" - 1/32" end play when the K.S. ratchet assembly has been fitted and secured with the nut on the end of the shaft. If the end float is excessive, it can be taken up by countersinking the securing nut so that its inner face projects over the shoulder on the shaft and forces the ratchet further along the shaft. It is inadvisable to use shims for adjusting end float."
I think end floats for all Burman boxes should be similar so your 21 thou should be well within the acceptable range.
Regards, Chris

chris.shearwood wrote:Hi Paul,
In the W/NG manual it states: "The mainshaft should have 1/64" - 1/32" end play when the K.S. ratchet assembly has been fitted and secured with the nut on the end of the shaft. If the end float is excessive, it can be taken up by countersinking the securing nut so that its inner face projects over the shoulder on the shaft and forces the ratchet further along the shaft. It is inadvisable to use shims for adjusting end float."
I think end floats for all Burman boxes should be similar so your 21 thou should be well within the acceptable range.
Regards, Chris

Thanks Chris....that's really quite interesting and what a way to reduce the end float; would never have thought of that!

End float is indeed critical on Burman gearboxes - which is why gasket thickness is also critical. Too many modern gaskets are far thicker than their paper predecessors. One simple way to reduce end float when your parts are worn is to omit the gasket altogether and use a thin layer of silicone suitably bolted up instead.

I agree 21 thou is OK. If you have none, the gear on the end of the ,mainshaft will bind. It would only need about .005 as a minimum. End float in all items inside a Burman gearbox can lead to problems. That includes the selector fork entire mechanism. Combined excessive end float can cause gears to disengage, if not straight away after some time. Nev

The dome has been repaired and I have new nuts and a tab washer from drags. The nuts are wider than the originals (requires a bigger spanner) and they might be a smidge thicker.

I'm not sure that they are on properly as they don't cover the thread even though they have been tightened. Also, the primary case doesn't seem to sit properly so I may need to grind out some of the weld. Does anyone think that these nuts should be sitting slightly proud of the end of the shaft like this? Maybe I need to find some better nuts?

Dave,

The Drags exploded diagram seems to suggest the tab washer goes between the two nuts. If this is the case, I think everything would go further on with a little bit of crankshaft thread protruding. As it is at the moment, I think the flat on tab washer is the limiting factor.

Not familiar with this set-up, but It seems unlikely that the sum of the thicknesses would be any different. I believe that three whole threads give 95% strength - I'm sure somebody will correct me if not.

The other obvious question is whether everything else is sitting correctly.

Did you have work done on the crankshaft splines at any stage, and if so is the geometry the same? Might the shock-absorber assembly be binding where the grooves start to chamfer?

Sorry if these are silly questions.

Hi Dave,
I used blue loctite on the two crank nuts and tightened them securely against each other. There is a about 3/32" of the mainshaft proud of the outer nut. It has been secure so far but not traveled many miles.
Excellent work on the outer primary cover Dave.
Ray