Clutch adjusting issue

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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G3L1946
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Re: Clutch adjusting issue

Post by G3L1946 »

Hi, gives it at 43 1/2 ins so near enough.

Steve
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Pharisee
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Re: Clutch adjusting issue

Post by Pharisee »

I'll add my tuppence-worth here. In March, 2016, I bought a 1955 AJS M18S from a dealer in Cornwall. I was told it was in excellent condition, having been recently restored by the previous owner... that was a right load of old toot!! Anyway... A little while later, I had cause to remove the primary drive cover. The clutch didn't look right. The 5 bolts appeared to be too long and were sticking way too far through the nuts. Further investication revealed that the previous owner has 'restored' it with 350cc parts, an 18 tooth engine sprocket, a short clutch hub and one pair of plates missing. I rebuilt it all with the correct 21 tooth sprocket, a new longer clutch hub and an additional pair of plates. I put it all back together and discovered that I had the same problem as Steve. The adjusting screw in the pressure plate went in too far for the lock nut to be secure. I checked that the steel ball was in place by fishing it out with a small magnet glued into the end of a length of 1/4" copper tube. That was OK, I had the correct length pushrod for the 500 configuration, but I still couldn't fit the locknut. In the end, I made a slightly longer pushrod from a length of silver steel and hardened the ends. That worked, but I was still puzzled as to why I'd had to do that.
Move on three years and I decided to rebuild the bike completely. I found the answer... The dowel in the operating mechanism was worn very badly, even though the steel ball was correctly located. I can only assume that at some time in the past, the ball had been fitted at the wrong end of the pushrod and the resulting friction between the dowel and the pushrod had caused the wear. Subsequently, the ball had been re-installed correctly, but the dowel left as it was. The dowel was replaced and the correct length pushrod used on re-assembly. All is now well with my clutch and the locknut fits correctly. Happy days...
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G3L1946
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Re: Clutch adjusting issue

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Hi Pharisee,

Thank you for taking time to provide that in-depth description of your experience. So glad it worked! This may be something I need to investigate further on my machine. Can I just ask, was it a big job to replace the dowel? I didn’t realise the dowel was separate from the cable mechanism Any special tools required or ‘top tips’ you may have would be much appreciated.
Thank you,

Regards,

Steve
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Rob Harknett
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Re: Clutch adjusting issue

Post by Rob Harknett »

Hi Steve, I owned a 9 months old 55 G3/LS from 1956 to 1962. Another from 1986 to date. I do not remember ever replacing a dowel, only a thrust rod. I was 17 when I changed a thrust rod. I never even had a workshop manual, but managed to do it with zero experience.
Your clutch cable wire should be 43 1/2" long. The casing length of 39 1/2" will give you the correct inner wire 4" slackness.
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Pharisee
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Re: Clutch adjusting issue

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G3L1946 wrote: Sun Sep 05, 2021 10:35 am Hi Pharisee,

Thank you for taking time to provide that in-depth description of your experience. So glad it worked! This may be something I need to investigate further on my machine. Can I just ask, was it a big job to replace the dowel? I didn’t realise the dowel was separate from the cable mechanism Any special tools required or ‘top tips’ you may have would be much appreciated.
Thank you,

Regards,

Steve
No special tools needed... it's held in place with a split pin. Take that out and it all comes to pieces. I changed the spring and the three balls at the same time as they were a bit rough and rusty. Once you've got the gearbox outer cover off, the release mechanism will just lift out.
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G3L1946
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Re: Clutch adjusting issue

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Cheers, so no great splitting of the gearbox as I feared! If it had transpired to be a long job I was going to speak to the local classic motorcycle enthusiast. He has a machine shop so your plan B ( longer rod ) was my next step.

Thanks ,

Steve
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G3L1946
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Re: Clutch adjusting issue

Post by G3L1946 »

Hi Rob,

Yes, the rod is absolutely no problem. My concern was centred around the dowel replacement. I’ll take a look at it to see if it needs replacing and do so if necessary. The rod is badly cupped at both ends and I’m not sure what has taken place with the mechanism prior to my ownership. I’ve noticed quite a few ‘Heath Robinson’ repairs and replacements during my renovation so giving it a quick once over may be worth while.

Thanks,

Steve
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G3L1946
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Re: Clutch adjusting issue

Post by G3L1946 »

Hi all,

After a stressful job removing the cover (now need new set of bolts as they were well and truly stuck fast )to examine the dowel this is what I found ( see photo ). To me, this looks a problem. The surface is quite deeply cupped and, when combining this with cupped rod, may be the problem ( as described by Duncan and Pharisee). I’m under the impression that neither rod nor dowel should be cupped. So, new rod, dowel and NOW set of bolts!

Regards,

Steve
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Pharisee
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Re: Clutch adjusting issue

Post by Pharisee »

That dowel is worn well past its serviceable limits. For the relatively insignificant cost of replacing it, I would dismantle the release mechanism and replace it. If the push rod is cupped, I would change that as well. With the worn parts replaced, follow the recognised procedure for the clutch adjustment and all should be well.
Well done in taking on the removal of the gearbox cover, particularly if it was your first time. If you're unaware of them, Draganfly Motorcycles keep a good stock of Burman spare parts if you can't get them from recognised AMC sources.
John
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G3L1946
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Re: Clutch adjusting issue

Post by G3L1946 »

Hi John,
Yes, new rod, dowel and balls to be ordered. The cost is minimal and worth getting it right.
I reckon that the replacement of these parts will solve the original problem. I was quite surprised at the actual amount of wear on the dowel.
Thanks for your help,

Steve
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