Thanks again Timetraveller, will get back to you tomorrow after chasing another lead.
Much appreciated from this Vincent newcomer
Kevin
Much appreciated from this Vincent newcomer
Kevin
Comet gearbox
- Thread starter redbloke1956
- Start date
Hoping to avoid confusion the ball between the clevis fork and the pushrod is 5/16" not 1/4". A 1/4" ball or roller may be found in a divided pushrod (non original mod). See KTB page 135.
Yeah, dead right,sorry for the error!
Just to cheer you up here are some problems I have encountered over the years with the Burman clutch lifting mechanism. The 5/16” ball can wear a neat concave end on the clevis fork so losing effective pushrod length. It can also do this to a lesser extent on the push rod end that bears on the ball. There is some dispute as to the correct length of the clutch push rod. The early spares list states 11 ¼”, KTB 11 3/8” and I have had new ones at 11 3/16”. Take your pick. There are two types of push rod thrust cup in the alloy clutch pressure plate. One (rare) is adjustable, as on the twin. If you have this you are lucky. The more common one is non-adjustable and is also prone to wear and deepen the hole the push rod sits in, again losing effective pushrod length.
The clutch activating arm has a ‘knobble’ that engages with the clevis fork. This also wears, as does the pivot at the bottom. (Note the technical terms.)
Finally there is the gearbox mainshaft end float. I have no idea what this should be but on some boxes it seems considerable and, of course, the whole shebang including the clutch moves to the left when the clutch is lifted, again shortening available lift.
I can only pose the problems. I leave it to all you clever people to furnish the solutions.
The clutch activating arm has a ‘knobble’ that engages with the clevis fork. This also wears, as does the pivot at the bottom. (Note the technical terms.)
Finally there is the gearbox mainshaft end float. I have no idea what this should be but on some boxes it seems considerable and, of course, the whole shebang including the clutch moves to the left when the clutch is lifted, again shortening available lift.
I can only pose the problems. I leave it to all you clever people to furnish the solutions.
Just because you are flogging us at cricket doesn't give you the right to confuse us with all that clever technical jargoney stuff as well Hugo...think I need a lie down...seem to be getting a headache....gets worse when I turn on the sports channel...and it's gettin bloody cold down 'ere too ....25C at ten pm
Thanks for all the gearbox info as that's the next job that needs doing on my Meteor.
There's masses of play in the mainshaft, but nothing a new thrust bearing shouldn't solve.
I had some related problems on the recent Giro di Sicilia - 1000 miles of hard riding through the Sicilian mountains in 5 days. In fact we had to pull the push rod out and add a ball just to get some additional length, and thus have a clutch that disengaged, instead of masses of freeplay. All this on the hotel forecourt of course.
Other than that I can't fault it at the moment, and it's giving me great pleasure - as the queen habitually tells us all on her New Year speech each year.
There's masses of play in the mainshaft, but nothing a new thrust bearing shouldn't solve.
I had some related problems on the recent Giro di Sicilia - 1000 miles of hard riding through the Sicilian mountains in 5 days. In fact we had to pull the push rod out and add a ball just to get some additional length, and thus have a clutch that disengaged, instead of masses of freeplay. All this on the hotel forecourt of course.
Other than that I can't fault it at the moment, and it's giving me great pleasure - as the queen habitually tells us all on her New Year speech each year.
Reading the messages, one (possibly) stupid question has not been asked. Are you sure your gearboxes are the heavy weight BAP box? Early post-war AJS's were fitted with a Burman box, and I believe that the kick-start cover is visually the same. If my memory serves me correctly, it is the main bearing at the sprocket end that is larger on the BAP box. Possibly all the gears and shafts are bigger too - hence the clutch pushrod not fitting.
It seems to me that there has always been a need for a parts diagram for the Comet box so that we know what we are ordering from the spares co. What are the thoughts of other Comet owners?
It seems to me that there has always been a need for a parts diagram for the Comet box so that we know what we are ordering from the spares co. What are the thoughts of other Comet owners?
Hi Rick, firstly I don't/didn't know there was a H/W and L/W BAP box, I am "reasonably" sure that BAP boxes were not fitted to AJS'S (I have an AJ and a Matchy and the pivot on those is at the top of the box not the bottom like the Comet)?
Most other parts have so far looked pretty identical.....I will check hole in the mainshaft on my Matchy tomorrow...maybe they are identical to the Comet mainshaft in everything but the hole?....and maybe both of my boxes have those shafts?.....almost anything could happen in 60 years I suppose.
Thanks mate.
p.s. used to knock around Ascot Vale a bit in my wild and Woolly days
p.p.s. Both the box IN the Comet and the spare are marked as BAP.
Hi Rick, if you look at my two earlier posting on this subject you will see that I have available both an A1 sized drawing and a couple of early hand books which could be photocopied. I made two copies of the drawing, one for someone local and one for Redbloke but he has not taken up the offer. If you would like that copy then let me know and it can be sent to you.
A Comet box pivots at the top, adjusted at the bottom.