Clutch impossibly heavy to operate - done everything - what's wrong ?

New springs?.  There are some duds out there, try the old ones. Only compress enough to kick it over without slippage.

... is the pivot to nipple centre distance on the lever? I'm not sure what yours should be (mine for a laydown box is 1 1/16") but if it's too big (as most aftermarket levers are) it will require a huge effort. Small distance = less effort required.

Having said that, you also report what sounds like dragging which suggests that there's not enough lift.

I assume the "AMC" type gearbox - have you checked that the operating lever in the box outer case is correctly located?

Pivot to nipple on an AMC box should be 7/8", same as a Velocette, Grove Classics sell suitable levers.

The difficult selection is due to dragging, reduce the pushrod end clearance,  but make sure that you have at least 1/8" because it decreases when hot and you can then get slipping.

The model 50 isn't a torque monster, so it could be worth trying it with a plate removed (just one, not one of each). Obviously needs enough 'grip' to start it and ensure no slip when in top gear, but less plates = more lift for the ones stiĺl there. This did work for another member with a M50.

Regards, 

George 

Have you got the correct operating arm in the gearbox? The ones for diaphragm clutches have different profiles, but look nearly identical.

Is the arm at 90 degrees to the cable?

Got to agree with Robert on this puzzle. Your replacement, longer springs are probably too heavy and/or becoming coilbound.  Unlike cylinder head valve springs which get seriously cooked with each long ride the clutch springs tend to have a much easier life and do not shorten as much with use.

Put the old springs back and see if this sorts the issue.

Attachment gives some clutch spring lengths.

Buckled plates ?      I had a similar problem. Someone suggested buckled clutch plates due to overheating from slipping clutch. When I skimmed  the clutch plates on a flat surface they were buckled (see image of uneven wear. The reverse would show contra wear ). It explained all the symptoms I experienced. To overcome the buckle, I had overtightened the clutch springs as an attempt to deal with the slip . This then made clutch action heavy and the lack of lift on the plates  (because of the buckle) caused the clutch to drag and find neutral . The solution was to skim the plates parallel and everything was good there after.

GRAHAM

While you are re-fitting the old springs  have a look at the outside faces of the spring cups which can get ridges worn on them from contact with the center face plate. 

The Model 50 already should have less plates as standard, 3 pairs + single sided as opposed to 4 pairs + single sided on the ES2 and twins. To keep everything else the same it also had a different, much deeper, pressure plate, this was pure penny pinching to save a couple of bob as it is no lighter to operate, just slips more easily, I have an ES2 clutch on mine.

If it has the standard pressure plate it needs to have 9 plates,if it has the M50 pressure it needs to have seven.

Is this a familiar bike that was running ok before, or is it a built-up bike out for the first time?

Because some bikes need them. The laydown and earlier boxes move the pushrod less for a given movement of the cable so need that extra travel (and the effort is commensurately less). My ES2 has 1.1/16 clutch and 7/8" front brake as the latter needs all the help it can get.......

As said, Grove sell 7/8" levers as does Steve Surbey at AMC spares.

Mike 

The standard pressure plate, where the taper section finishes at the clutch plate end has just a slight lip, say 1/16", the M50 one carries on at the larger diameter for about 5/16" IIRC. I'm at work just now so I can't  measure it but it is a big enough difference that you couldn't  mistake it once you know.

The different lever pivot centers will make a considerable improvement to the pull effort ,but of course the reduction in lift also  means that everything else needs to be correct. With clutch springs I found that length is not the only thing that needs to be correct. Spring wire  gauge and temper are important too. As just about everything we buy is made (we hope!) to pattern there is always the possibility that some changes have crept in unnoticed. I am never in a rush to discard orriginal parts but there is also a need to keep the supply chain working. Hey ho. 

HI Mike Have you changed the clutch centre ( spider) it could be the early centers had lips on the ends of the splines and they get crushed over time and let the back of the centre bind on the sleeve gear ( sprocket carrier ). The later centres have a full washer fix in it for the spring washer and nut to hold the clutch on to the main shaft. I have found this fairly common.  

Hi Mike. If you have not yet solved the problem, I have another suggestion. Take all the clutch plates out and check the order they should be put back with the diagram in the handbook. I have seen a clutch with a plain plate innermost. It then needs the springs screwed in too far to stop clutch slip......and an impossibly heavy feel at the handlebar lever. 

Best of luck......Doug

If your clutch chain wheel has inserts then it is older than the bike, the backplate should therefore be a plain one and IIRC you should have four plain and three friction plates with no half and half one, but the main thing is that with the pressure plate you have that there is enough compression left in the springs to allow the clutch to free off before they become coil bound.  If you don't  have  enough plates in that is a real possibility . How many plates and what sort?

The attachments show what your bike should have and one of the later SS clutch variations.

Clutch pressure plates. Hi again. Doug here (Richard is my son).

I don’t have a pressure plate to compare to the pics. But what I do know is that because the Model 50 had two fewer plates than the ES2, the pressure plate for the M50 curls in more to take up the space.

Hi Mike,

relax and don't overthink this, the set up you describe should work fine.

Take the centre adjuster out of the pressure plate, then assemble your clutch as you described it, tighten the springs up evenly until the kickstart doesn't slip against compression then put your adjuster back in and tighten it up whilst feeling the free play in the pushrod by wiggling the actuator through the round window in the gearbox cover until you have about 1/8" movement where the cable goes on and tighten the locknut. Set the cable with about 1/8" free play also.

This is a starting point, by test adjust the springs  up as necessary, but each time check the free play on the pushrod and cable.

Good luck

Getting the clutch to lift and spin evenly  is a bit of  an art.  Not helped  by the drum which has enough slop on its bearing  to wobble and confuse the issue. I set up a dial gauge  which takes out the guesswork and ignores the wobbly drum. I set it up on the pressure plate and take readings at the point the clutch is starting to  drag. New plates will settle down and grip better and may need a couple of adjustments.