Clutch goings on and off!

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
55mat
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Clutch goings on and off!

Post by 55mat »

55 matchless g80s, my clutch fell off twice in a mater of days. Eventually traced to the inner basket being worn beyond belief so was slipping off and undoing the nut on the mainShaft. Right, all the nice bits back on, set all the clutch up pull the clutch in and it goes lose with a ping! (B52 gearbox) I just read a problem on the forum which seems to be the same but it doesn't say how to fix it. I think it is something to do with the gearbox end. Will I have to take off the gearbox cover? Can anyone help me out the in beautiful jampot land...
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clive
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Re: Clutch goings on and off!

Post by clive »

I think it is a click from the operating mechanism at th gearbox end. To prevent this adjust the cable so that there is a small amount of free movement at the handlebar. Then screw in the adjuster on the clutch pressure plate until the plate starts to move out. Turn it back about half a turn and lock it up. It should now work without clicking.

if the operating arm has pulled right round too far you should be able to lever it back wihout removing the cover (I think)
clive
if it ain't broke don't fix
SPRIDDLER
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Re: Clutch goings on and off!

Post by SPRIDDLER »

Not clear exactly what you mean by 'goes loose' but a common error is made by not completely slackening off (preferably disconnecting) the clutch cable at the gearbox end when the pushrod adjustment is made on the screw and locknut in the clutch pressure plate. If that is not done the ball between the moving plate and the fixed plate at the gearbox end starts off too far along its 'ramp' and when the clutch lever is pulled in it will overrun its 'ramp' with a 'click' and the h/bar lever may not return to its normal at rest position, remaining floppy. If you look (in Christians Archive) at an exploded drawing of the B52 clutch you will understand better the problem you have (and my contorted explanation).
It is important to understand that the adjuster at the end of the clutch cable is only there to adjust the amount of slack in the cable. It does not adjust the clutch!

Here you are; complete instructions and clear photos of the Burman clutch rebuild/reassembly. The fixed and moving plates to which I referred above and the ball between them are clearly shown on the third page, notated 'A' and 'B'.
Note that there is also a ball at the offside (i.e. not the clutch end) of the clutch pushrod.

http://archives.jampot.dk/technical/Tra ... ebuild.pdf
Last edited by SPRIDDLER on Tue Jun 21, 2016 11:51 pm, edited 4 times in total.
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Rob Harknett
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Re: Clutch goings on and off!

Post by Rob Harknett »

You said a nut slips off. Have you not got a tab washer fitted??
55mat
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Re: Clutch goings on and off!

Post by 55mat »

Thank you Rob, yes I have put a new tab washer on every time.
Also, thanks to Clive and spriddler, you are getting me nearer to the problem. Many thanks for the diagram spriddler, I Have read it and I am sure the problem is at the gearbox end as Ken refers to in his piece that says " if it produces a clonk the clutch operating mechanism needs attention" I think this is the area I need to be looking at.

Here's hoping you are right Clive that I can lever it back without taking the gearbox cover off, which I don't mind but I have No garage and working outdoors in this piss poor summer Is so much fun...

Another funny thing is it all seemed to work fine before but there were two ball bearings in front of the thrust rod? Have I got the wrong length thrust rod in? I can't find anywhere that tells me the lengths. Anyway I will now set about trying to lever it back.

Really appreciate all the info from you chaps, keep it coming and I will also let you know how I get on for the benefit of others.
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Rob Harknett
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Re: Clutch goings on and off!

Post by Rob Harknett »

I do not think I have ever had this click/ clonk?? However, after a lay up, I have found things feel stiff when operating the clutch lever ( 1955 gearbox ) I just remove the oil filler and give the moving parts of the clutch operation parts in particular, a real good spay of WD 40. My prewar grease filled boxes get the recommended egg cup full of oil thrown in.
SPRIDDLER
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Re: Clutch goings on and off!

Post by SPRIDDLER »

55mat wrote: Here's hoping you are right Clive that I can lever it back without taking the gearbox cover off, .
You almost certainly will be able to push it back without any dismantling. I had the same problem with my first Matchless 16yrs ago and it was the Venerable ITMA, late of this parish who put me straight.
Just remove the oil filler plug, disconnect the clutch cable by lifting the nipple out of the slot in the moving plate inside and then push the bit (it's like an ear)where the nipple was, to the left (the opposite way to that which the cable moves it). It should be quite easy and not need any forceful 'levering'.
Don't refit the cable until you've adjusted the clutch at the pressure plate screw. Then refit the cable with its adjuster screwed right in and then adjust the cable to give a bit of free play at the handlebar lever.

Re the pushrod/two balls, there should be only one ball as in the diagram to which I referred you. If the pushrod is too short (?) fit a second ball at the clutch end of the pushrod inside the pressure plate adjusting screw then you will be able to remove it easily when/if you get the correct pushrod.
(It may be that the PO had to fit two balls due to previous incorrect assembly of the clutch, or because the two plates with the ramps and ball have been over-adjusted and run out of 'throw' which is why you have to deal with that issue now).
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Andy51
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Re: Clutch goings on and off!

Post by Andy51 »

Hi, I had the same problem with my '54 G80 a few years ago. Yes, you can free the lever in the gearbox through the filler cap aperture, but it will go again - you might get one or two gear changes if you are lucky. I had to ride home doing clutchless gear changes! There should only be one ball, at the gearbox end. I solved the problem by adjusting the screwed adjuster in the clutch alloy pressure plate till there was just free play, not the recommended half turn. I then adjusted the cable to give 1/16 play, and all has been good since. Andy
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Re: Clutch goings on and off!

Post by ajsph »

The 1955 spares list says, that the rod should be 10 3/16" long for five plate clutch and one 5/16 ball
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Re: Clutch goings on and off!

Post by Group Leader »

I too appear to have developed the stiff "Clicky/Clunk" clutch operation! :cry:

Having read the various posts and that very useful article I thought I would have a go at the clutch rod adjustment as described but, before I do, I was just wondering if it is possible and, if so advisable, to remove the lock nut, thrust cup and rod with everything else intact for the purpose of inspecting it and lubricating it?

My intention would be to use a small magnet fixed in an ali tube to extract the rod out but, of course, I don't want to do this if the ramp and ball at the lever end would then be free to move/drop out!

Whilst I think I understand the general principle of operation using the ramp to create the longitudinal movement I can't say I can exactly visualise how the two levers and the ball arrangement work in practice without the ball shooting out!

Any advice, photos and/ or video clips would be much appreciated!

TIA

Alan
1953 AJS 16MS, 1939 BSA 250 and a 1/3 scale Sopwith Triplane but that's another story ..... :lol:
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