Clutch goings on and off!

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
Mick D
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Re: Clutch goings on and off!

Post by Mick D »

Group Leader wrote: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!
If you check the parts catalogue for your year you should see that there are three pairs of matching ramps arranged on two 'basically' circular discs, each pair of ramps houses a ball. Rotating one disc in relation to the other causes the balls in the ramps to separate them and give the longitudinal movement via the push rod / ball.

Regards Mick
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dave16mct
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Re: Clutch goings on and off!

Post by dave16mct »

You are ok to remove the adjuster and pull out the pushrod from the clutch end. The ball can't escape into the gearbox end. Remember to measure the rod length to check you've got the right one and also it should be 5/16" dia. Lightly grease before putting it back. Loosen the cable adjusters off before adjusting the thrust rod, then the cable.
Dave.
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Rob Harknett
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Re: Clutch goings on and off!

Post by Rob Harknett »

I've been riding a 55/G3LS since late 1956. Had no manual or forum back then in my teenage years, just the old boy across the road to question. If you do as the manual states or advised here you should be OK. There is one thing that has not been mentioned, that is the bike is now over 60 years old. You cannot relate back to how the bike ran when almost new. The bike then worked fine. Used every day, thrashed every day, main problem was punctures etc. Tubes then covered in patches. Vibration, rattles, clicks clonks etc. Were not a problem, that's how they were. They were only perhaps more so, as we never wore crash helmets then, had better hearing, so heard funny noises more so. We enjoyed riding our bikes then. We did not spend more time taking them to bits than riding, worried about a little clicking noise. As for the device with the little ball. Providing you have the clutch, cable etc all set up correct, before you ride your bike after a lay up or it's not being used much. Take off the oil filler nut, lubricate the device. A good spray of WD 40 works OK for me. The ball etc will then clean up a little surface rust and roll instead of drag and click. You should feel the action easier when operating the lever. You may also need to pay more attention to the thrust rod. That too will get surface rust and seize a bit. Never needed much attention years ago when bikes were used, but will require regular cleaning when not often used. When admiring you nice clean shiny bike, look more closely at the bits you missed. That being the bits that work. Which you may find dry, no grease with surface rust. It is quite easy to spot a bike that suffers from this. Just look at the front brake fittings at the bottom cable end. Is there any sign of grease around the clevis pin and other working parts.? Since I started typing this I see Dave has made comment of thrust rod lubrication, I have also mentioned.
56G80S
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Re: Clutch goings on and off!

Post by 56G80S »

I've had both B52 and AMC gearboxes in the Matchless.

The advice quoted above works. Start with the cable completely released and the gearbox end with the two plates and the the balls between them with the balls at the "bottom" of the depressions in other words "idle". Fully released clutch cable. Adjust the clutch thrust rod using the screw and locknut in pressure plate (from memory the spark plug spanner fits the locknut so if you have the appropriate spanner you can hold the screw in place while tightening the locknut). Don't overdo screwing the screw in or you'll pre-tension the opposite end of the clutch rod and will be back with the same problem you had.

Only then move on to adjusting the cables.

As an aside, for smoother clutch operation, particularly AMC, make sure everything at the gearbox end lines up nicely so the cable has a straight run through. This also avoids annoying fraying and breakages when you least want them (don't ask how I learnt this). If it's not it's worth doing.

Johnny B
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Group Leader
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Re: Clutch goings on and off!

Post by Group Leader »

Mick D wrote:
Group Leader wrote: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!
If you check the parts catalogue for your year you should see that there are three pairs of matching ramps arranged on two 'basically' circular discs, each pair of ramps houses a ball. Rotating one disc in relation to the other causes the balls in the ramps to separate them and give the longitudinal movement via the push rod / ball.
Thanks Mick I'll take a look although I can already appreciate its workings now from your clear and concise description.
dave16mct wrote:You are ok to remove the adjuster and pull out the pushrod from the clutch end. The ball can't escape into the gearbox end. Remember to measure the rod length to check you've got the right one and also it should be 5/16" dia. Lightly grease before putting it back. Loosen the cable adjusters off before adjusting the thrust rod, then the cable.
Thanks Dave,

I've done ~2500 glorious miles on it (already :D ) and it's generally been OK until this last week hence I presume the length should be correct with the exception of any wear. The motion is stiff/ sticky and jerky hence my desire to whip out the rod and lubricate it before having a go at adjusting it as described in that article. I'm very keen on not having to strip and rebuild the gearbox in order to retrieve lost bits and thus reluctant to just give it a go so your advice is much appreciated and I can now dive in!

Thanks once again chaps.

Alan
1953 AJS 16MS, 1939 BSA 250 and a 1/3 scale Sopwith Triplane but that's another story ..... :lol:
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Group Leader
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Re: Clutch goings on and off!

Post by Group Leader »

Well the rod was extracted and was found to be straight but slightly short of the specified length by ~1/32". The actuator end did not seem to be overly hard and had a ball shaped depression in the end which was maybe another 1/32" deep (not certain if they were supplied with that or not although I'd assumed not from advice about how easy it is to fabricate one). With the assistance of a friend we came to the conclusion that the already short rod and the dent (wear?) in the end of the rod was causing the problem.

As it was, the operating lever was close to being at 90 degrees to the cable in the at-rest position and when operated it moved well past the "over-centre" position during which motion the jolt as the balls went over the ends of the ramps, as described by Mick, occured. So, I've re-hardened the rod ends and inserted a smallish (~1/8") diameter ball at the clutch end (retained by some thick grease and the shrouded nature of the adjusting nut) to effectively recover the missing bit of rod as a temporary measure. I've also re-routed the clutch cable as advised to a far more smooth if not as well hidden path, lubricated the rod and adjusted the nut prior to connecting the cable.

The result is that the clutch operation appears to have been restored to a "smooth and easy" operation although it was too late for this "daylight biker" to go for a test ride by the time I'd finished to confirm that all was indeed well!

I shall either buy or make a replacement rod of the correct length and ditch the additional ball as soon as I can (I don't really like the idea of it in there even though it can't actually go anywhere!).

Many thanks for the advice and useful information chaps.

Alan
1953 AJS 16MS, 1939 BSA 250 and a 1/3 scale Sopwith Triplane but that's another story ..... :lol:
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Group Leader
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Re: Clutch goings on and off!

Post by Group Leader »

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