Burman CP box and clutch

[clive]

My G3 has been getting difficult to engage and disengage first gear. Bit of an investigation today and I found that i had fitted the later B52 clutch with relatively new plates but i think only 4 plates in a 5 plate basket and centre. The drive edge of the internal strips in the basket are showing signs of wear. So far so good I have the extra plates and can file back the strips. BUT the whole basket moves in and out by about 1/4 inch. The clutch centre does not seem to be loose so what is likely to be going on in the gearbox? Or is it because the B52 clutch is actually not a swop for the CP clutch? Thanks for your thoughts.

[SPRIDDLER]

My G3 has been getting difficult to engage and disengage first gear. Bit of an investigation today and I found that i had fitted the later B52 clutch with relatively new plates but i think only 4 plates in a 5 plate basket and centre. The drive edge of the internal strips in the basket are showing signs of wear. So far so good I have the extra plates and can file back the strips. BUT the whole basket moves in and out by about 1/4 inch. The clutch centre does not seem to be loose so what is likely to be going on in the gearbox? Or is it because the B52 clutch is actually not a swop for the CP clutch? Thanks for your thoughts.

I can't really help Clive and you know your way around these old bikes well enough so will be familiar that the difficulty selecting 1st when stationary is usually due to the plates not separating sufficiently. Maybe the movement of the basket results in insufficient 'throw' of the thrust rod to free the plates when selecting 1st gear? As you rightly said, notches in the thrust side of the plate 'ears' won't help.
I assume you have the BP clutch and CP 'box and I'm sure I've seen a techy article or a post that refers to needing a spacer behind the basket. I did see a couple of references to spacers in posts by Johnny B and Spookefoote who have used alternative B52/CP clutches to those which were fitted to the bike's ex-factory standard gearboxes. However, I can't find them now but whilst looking I came across this which mentions that the B52 mainshaft is shorter than that of the CP but can't decide whether it's significant to your issue.

B52 upgrade from CP b.jpg

[clive]

Thanks Sprids. I am thinking the nut at the kickstart end may be loose. Cannot think of any other reason for the movement.

[SPRIDDLER]

I am thinking the nut at the kickstart end may be loose.

It's not uncommon at our age, Clive.

[clive]

It's not uncommon at our age, Clive.

Ever helpful Sprids. Wish i was as young and active as in that photo you used to bring out regularly.

[SPRIDDLER]

Ever helpful Sprids. Wish i was as young and active as in that photo you used to bring out regularly.

I think you must mean this one.

Clive at St Bernard pass.jpg

Or on second thoughts I expect you mean the one from The Great Wrinkly Bake Off.

Clive's b'day.jpg

[clive]

Yes the birthday cake is the one. About 10 years ago.

[56G80S]

Hi Clive,

Sprid is right, I use the reverse setup, B%" box and CP clutch. I did have a bit of a chew getting the clutch rod the right length and probably need to do some adjustment to the clutch itself as it seems a bit extra clunky at the moment. Last Monday was the first run out since Salisbury but only about 50 miles. I did have a problem with the basket and the centre not both being for the same number of plates and running with 4 plates which confused the clutch rod length matter! It's fine as I'm very light, even more since the cancer, so although it's a 500 there's no slippage even loaded for rallies.

But I didn't need any spacers etc. and had used this setup previously for 4-5K before a break using the AMC box and clutch and deciding that the AMC one needs some refurb.

Johnny B

[clive]

Thanks Johnny, i think it was all working ok some years ago when i first put it together. Will try to get to the garage today fir an hour or so and investigate the kickstart end. I am hoping its just the nut that is loose and it will be an opportunity to use my Lidl rattle gun! I did notice the need to adjust the clutch pushrod regularly and it should have been a clue something was happening.

[clive]

Well it does seem the nut at the kickstart end was a bit loose and ttightening it up did reduce the movement but not completely. That was achieved by using a washer but the gearbox did not then turn. So i will make do with a bit of movement which will mirror the movement of the engine! Incidentally with the rattle gun i have found a new way of stripping threads. Fortunately the nut gave up well before the thread on the shaft. Next task check the pushrod adjustment as the engine can be turned over by hand on the engine sprocket, if not it was running fine so leave well alone!