1954 model 18 ajs clutch jumping/snatching

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
User avatar
AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

1954 model 18 ajs clutch jumping/snatching

Post by AJS 500 »

Can anyone help.
I've been having problems with my clutch grabbing, snatching, when I pull away, bike kind of kangaroos up the road. I have rebuilt the clutch replacing steel and friction plates, also new spring and adjusting bolts. New inner race bearings as well. There seems to be no excessive wear on the basket etc. I have set the clutch operating work up as per the book spec. All ball bearings are present and new and are the correct sizes. When I first take the bike out all operates as it should until a steep hill start or a quick/ hard pull away due to unexpected clowns. Then the shuck shuck noise comes from the clutch side and kangarooing appears as the clutch starts snatching again. I've stripped the clutch and found nothing took her out and all operated great until clown time or steep hill pull aways, loading the clutch. Then bike kangarooing as clutch snatching returns very frustrating. Anyone had similar and can advise please...probably something stupid I'm overlooking...


Sent from my iPad using Tapatalk
JimFitz
Posts: 663
Joined: Thu Feb 27, 2014 9:27 am
Location: Kent, England

Re: 1954 model 18 ajs clutch jumping/snatching

Post by JimFitz »

Could it be that the engine sprocket nut which tensions the shock absorber spring has come loose and is allowing the sprocket to slip round the cams. Happened to me once and certainly feels like a jerky / slipping clutch.
Too old to Rock and Roll but too young to die.

1952 G80 rigid, 1960 G12 DL / Watsonian Monza, 1954 G80S.
User avatar
AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

Re: 1954 model 18 ajs clutch jumping/snatching

Post by AJS 500 »

Yeh I thought that but alls tight and correct. as far as I can tell it's not jumping, I made a spacer to compress the spring a tad more just in case it had lost some tension.


Sent from my iPad using Tapatalk
User avatar
AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

Re: 1954 model 18 ajs clutch jumping/snatching

Post by AJS 500 »

AJS 500 wrote:Yeh I thought that but alls tight and correct. as far as I can tell it's not jumping, I made a spacer to compress the spring a tad more just in case it had lost some tension.


Sent from my iPad using Tapatalk
Also every time I strip and rebuild the clutch it works fine until loaded. I have another clutch from the same year on a Greenlander I built from bits laying about, might try swapping it all over and seeing if it makes any difference.
A lot of messing about though, hoping to find out the why and fix it....hmmmmm


Sent from my iPad using Tapatalk
SPRIDDLER
Member
Posts: 8542
Joined: Wed Sep 01, 2004 1:00 am
Location: WEST SUSSEX UK

Re: 1954 model 18 ajs clutch jumping/snatching

Post by SPRIDDLER »

I'm assuming you have the standard B52 'box and 5 spring clutch.
Evidently the problem only exists (or is only noticeable) under high load.
Was this problem occurring before you o/hauled the clutch with new parts?
Does the snatching occur whilst the clutch h/bar lever is being eased out or after it is fully released?
I'm a little surprised that you have needed to (or were able to) fit a spacer to increase the shock absorber pressure since from memory (poor) it's quite a job to get the nut started as it is, never mind with an additional spacer. Obviously you have fitted the dished cap between the nut and spring :? The 500 has a stronger s/absorber spring than the 350's. Could yours have a 350 spring?

Various random thoughts......
Primary chain snagging on the dynamo chain? (Recipe for a real disaster!).
Do the new friction plates have individual 'corks' or a continuous bonded lining? If bonded, maybe part of a lining is unstuck.
Are the 24 clutch rollers the correct ones? From memory they are fractionally shorter than 'standard' 1/4" rollers.
Clutch basket nut not really tight?
If the primary chain is badly stretched perhaps when under high load the links are not engaging cleanly with the engine or clutch sprocket teeth. (Long shot!)
Is the actuating mechanism at the r/h side of the 'box (3 balls, a fixed and moving plate) correctly assembled?
Does the clutch release pushrod move freely and is not rusted/gummed up/bent?
Are the 5 new clutch springs free to move in their cups and not binding under high load when the clutch is being engaged?

(Must stop wittering now and decant the Claret for dinner............. ;) )

After dinner thought...........
You don't say what other work you have done but is the spacer 010629 in place?
Drive axle spacer '54.JPG
You do not have the required permissions to view the files attached to this post.
'There is a tide in the affairs of men
Which taken at the flood............'
Andy51
Member
Posts: 742
Joined: Thu Mar 31, 2005 1:00 am
Location: BERKS UK

Re: 1954 model 18 ajs clutch jumping/snatching

Post by Andy51 »

Hi, not had this problem, but when I bought my G80, I found the PO had assembled the clutch using standard length .25 in rollers, thus locking them up. However, the clutch still worked OK (after I had sorted out the release mechanism - I only discovered the incorrect rollers much later). So, from my experience, faulty release mech or incorrect rollers will not cause your problem. Have you checked if you have the proper 5 plate clutch components - using the shorter 4 plate 350 clutch inner could result in clutch plates lifting over the rim and jamming? Cheers, Andy
User avatar
AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

Re: 1954 model 18 ajs clutch jumping/snatching

Post by AJS 500 »

Ok, the clutch is the standard 54 clutch for the 500. All springs are free to move in the cups but I will check again. The front sprocket is correctly fitted, with front spacer. The spacer I made was to elevate my concerns as the spring seems to have lost tension, thinking this was the problem.
The bike was rebuilt by myself a couple of years ago with gearbox stripped and all worn parts replaced including the balls for the clutch release mechanism.
This is set to book spec. Burman GB 54 gearbox fitted.
The jumping once it starts is then present all the time. New primary chain fitted and is correctly tensioned.
I will check clearance with Dynamo chain,
I had a nightmare with a previous rebuild with Dynamo sprocket coming loose as standard nut fitted. I now use modern nylock nuts and just to be safe 242 thread lock.
I'm going to pull it all apart Thursday and scrutinise going over all suggestions so far..thanks all.



Sent from my iPad using Tapatalk
User avatar
AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

Re: 1954 model 18 ajs clutch jumping/snatching

Post by AJS 500 »

ImageImage

Primary drive Clutch photo taken during rebuild.
New clutch plates have separate corks.
New steel plates are correct thickness.
New pushrods all parts spotless on rebuild.


Sent from my iPad using Tapatalk
User avatar
AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

Re: 1954 model 18 ajs clutch jumping/snatching

Post by AJS 500 »

Andy51 wrote:Hi, not had this problem, but when I bought my G80, I found the PO had assembled the clutch using standard length .25 in rollers, thus locking them up. However, the clutch still worked OK (after I had sorted out the release mechanism - I only discovered the incorrect rollers much later). So, from my experience, faulty release mech or incorrect rollers will not cause your problem. Have you checked if you have the proper 5 plate clutch components - using the shorter 4 plate 350 clutch inner could result in clutch plates lifting over the rim and jamming? Cheers, Andy
Cheers Andy, it's the correct inner, found that problem on another 500 I purchased before, purchased the correct inner off eBay for £40!
C.


Sent from my iPad using Tapatalk
User avatar
AJS 500
Posts: 38
Joined: Wed Aug 05, 2015 5:27 pm
Location: KENT UK

Re: 1954 model 18 ajs clutch jumping/snatching

Post by AJS 500 »

SPRIDDLER wrote:I'm assuming you have the standard B52 'box and 5 spring clutch.
Evidently the problem only exists (or is only noticeable) under high load.
Was this problem occurring before you o/hauled the clutch with new parts?
Does the snatching occur whilst the clutch h/bar lever is being eased out or after it is fully released?
I'm a little surprised that you have needed to (or were able to) fit a spacer to increase the shock absorber pressure since from memory (poor) it's quite a job to get the nut started as it is, never mind with an additional spacer. Obviously you have fitted the dished cap between the nut and spring :? The 500 has a stronger s/absorber spring than the 350's. Could yours have a 350 spring?

Various random thoughts......
Primary chain snagging on the dynamo chain? (Recipe for a real disaster!).
Do the new friction plates have individual 'corks' or a continuous bonded lining? If bonded, maybe part of a lining is unstuck.
Are the 24 clutch rollers the correct ones? From memory they are fractionally shorter than 'standard' 1/4" rollers.
Clutch basket nut not really tight?
If the primary chain is badly stretched perhaps when under high load the links are not engaging cleanly with the engine or clutch sprocket teeth. (Long shot!)
Is the actuating mechanism at the r/h side of the 'box (3 balls, a fixed and moving plate) correctly assembled?
Does the clutch release pushrod move freely and is not rusted/gummed up/bent?
Are the 5 new clutch springs free to move in their cups and not binding under high load when the clutch is being engaged?

(Must stop wittering now and decant the Claret for dinner............. ;) )

After dinner thought...........
You don't say what other work you have done but is the spacer 010629 in place?
Drive axle spacer '54.JPG
Cheers for replying,
Not sure about the rollers, good point though, I will check. Centre nut is good, machined a stainless one as the original had dodgy threads, also made a new lock tab. Will check the movement of the springs in the cups,
Front sprocket is all good, I made a spacer as the spring although the correct one has lost some of its tension and this seems to be ok but I will recheck. It's most parts replaced on rebuild but I didn't check the new pushrod, worth a check, might be slightly oversize limiting heat expansion movement as well.
Thursday the day I strip it down, might swap it out for an alternative clutch if I find no solutions to see it it makes any difference.


Sent from my iPad using Tapatalk
Locked