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

Re: 1954 model 18 ajs clutch jumping/snatching

Post by AJS 500 »

AJS 500 wrote:
Andy51 wrote:The outer clutch basket is, I believe, common to both 350s and 500s; the inner clutch centre is shorter for the 350. Removing a friction and plain plate is certainly worth trying, it will at least eliminate one possible source of trouble. Andy
Inner size is different, NOT a 350 clutch fitted. I found the new bonded friction plates are thicker than the original corks so I removed one. Clutch works fine now I've changed to rollers to the correct size.

Image


Sent from my iPad using Tapatalk
Believe there is almost 1/2" difference in the basket septa, outside diameter and chain wheel are the same.


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:
AJS 500 wrote:
Andy51 wrote:The outer clutch basket is, I believe, common to both 350s and 500s; the inner clutch centre is shorter for the 350. Removing a friction and plain plate is certainly worth trying, it will at least eliminate one possible source of trouble. Andy
Inner size is different, NOT a 350 clutch fitted. I found the new bonded friction plates are thicker than the original corks so I removed one. Clutch works fine now I've changed to rollers to the correct size.

Image


Sent from my iPad using Tapatalk
Believe there is almost 1/2" difference in the basket septa, outside diameter and chain wheel are the same.


Sent from my iPad using Tapatalk
Depth even...


Sent from my iPad using Tapatalk
Dixter
Posts: 102
Joined: Mon Oct 02, 2017 8:27 pm
Location: Seattle area, WA USA

Re: 1954 model 18 ajs clutch jumping/snatching

Post by Dixter »

Now that you have identified the rollers as a problem, you might want to remove the spacer from the engine shock absorber. As originally designed, upon high loading the outer movement of the cam is limited by placing the entire load on the hardened steel nut, before the spring can become coil bound.

If the spring becomes coil bound, the load is now upon the outer edge of the cup, and the cup can fail. This mode of failure was common on a batch of cups, when an aftermarket vendor got the dimensions wrong.

Ciao,
Dick
Dick Casey
The RideNut
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 »

Good news, Clive.
BTW - those deep notches worn into the bars in the 350 basket won't (didn't) aid a smooth clutch, making the action more like that of a ratchet.
Basket notches.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............'
User avatar
Pharisee
Member
Posts: 1126
Joined: Tue Mar 15, 2016 8:51 pm
Location: Lincolnshire UK
Contact:

Re: 1954 model 18 ajs clutch jumping/snatching

Post by Pharisee »

I had cause to contact AMC Classic Spares recently regarding my clutch. I hope Mr Surbey won't mind me quoting part of his reply here as I think it is relevant...

"For the first half of the B52 clutch's life, they used a different basket for the 350cc....... If you measure inside the basket, a 500 will be 1 7/16” deep and a 350 will be 1 1/4”, similar dimensions to the different centres. Thankfully they saw a bit of sense and used the same basket for both in the latter part of the B52 clutch's life."

John
I'm from the Fens.... Gimme six.
User avatar
Pharisee
Member
Posts: 1126
Joined: Tue Mar 15, 2016 8:51 pm
Location: Lincolnshire UK
Contact:

Re: 1954 model 18 ajs clutch jumping/snatching

Post by Pharisee »

I'd been warned that some of the new clutch centres on the market are of dubious quality. The one I did buy looked ok, however, having assembled the clutch with the new longer centre hub, 5 friction plates and 6 plain plates I had a problem. The disc pack was marginally too thick and when correctly adjusted, the final friction plate had a tendency to become disengaged from the outer basket when the clutch was operated and jam up. Not ideal!
Having pulled it all apart again, I discovered the problem. The raised flange at the inner end of the new centre hub was much thicker than the flange on the old hub that I'd taken off, effectively moving the whole disc pack out by around 70 thou... approximately the thickness of a plain plate.
I put it up on the lathe and turned the flange back until it was the same thickness as the flange on the old hub. That done... the clutch went back together again perfectly.
20180612_132613-small.jpg
20180612_160142-small.jpg
You do not have the required permissions to view the files attached to this post.
I'm from the Fens.... Gimme six.
Locked