what's with clutch / shifting problems???

I posted a question about 3 or 4 weeks ago when I suddenly started to have intermittent shifting issues (Mark 3 with 17K miles).

The bike would occasionally slip out of first gear as I revved away from a stop, and it would occasionally refuse to go from 3rd to 4th. (it may have been stubborn from 2nd to 3rd as well, but I particularly remember 3rd to 4th).

And the shifting just didn't seem to be smooth either.

Then the clutch cable broke.

I replaced the cable but realized the clutch feel was way off. It is a very hard pull, and it feels like the plates are fighting me. I parked beside another Mark 3 a few days ago to compare clutch pulls. The other one was smooth s butter and I could feel the clutch lifting. Mine is just not right.

I have been scratching my head to figure out what is wrong and can't seem to get to the bottom of this.

Words of wisdom would be greatly appreciated .....

So far:
- checked new cable - it's fine. I even swapped a couple of others in and out - same. It is routed nicely, no binding in the cable.

- the clutch actuator plate in the gearbox moves cleanly on its ball and is i perfect condition. It is lined up perfectly with the cable's line of entry into the gearbox cover.

- the clutch pushrod is straight and right on spec for length. It moves cleanly through its channel when the clutch adjusting screw is removed and the clutch lever is pulled. I can push the point of a philips screwdriver against the rod and work it back and forth via the lever. Nice and smooth.

- the clutch plates are all nice and kosher. No gouges or marks on inner or outer teeth.

- removed the primary chain, and engaged the clutch without the chain in place. it still feels like crap, no difference from when the chain is on - so that rules out possible sprocket alignment as an issue.

- I have poked around at this problem for days, and took it to a shop which regularly works on Commandos. They couldn't figure it out either.

Now, I guess I would be ok with a tough-guy clutch pull, which would give me a strong left wrist and I'd have to replace cables regularly, but he shifting issue is really a pain in the ass.

Any suggestions what else to look for? It's as if the clutch basket itself is warped or something, preventing the plates from lifting when the pressure plate is on. But I have pulled the plates out 3 times now - they all slide in and out of the basked nicely.

Help..............

Keith Kelly

PS - Barnett clutch plates on the bike, put on about a year and a half ago. But this problem just came up recently.

maybe time to peek inside the gearbox.

As your friction plates have worn, the stack height shrank.

You are now below the optimum minimum; try re-installing the old bronze plates and see if it "comes back".

If so, time to replace your friction plates.

While you're in there looking at the clutch, take a look at the clutch center. When the notching gets too bad it makes the plates hang up, causing clutch drag and difficult shifting.

Someone else posted recently about slipping out of first gear. In his case, as I recall, shimming the layshaft fixed it. You need to do that with the roller bearing. You could give the kickstart shaft a wiggle and see how much end play there is. OldBritts has a tech article about the shimming procedure.

Debby

Grandpaul / Debby - appreciate the suggestions and please keep 'em coming.

- the Barnett plates only have a couple of thousand miles on them, very little wear and I already checked the stack thickness vs the original places - A-OK.

- clutch center is free of notching. But as far as shimming the layshaft - hmmmm, maybe. I'll check.

It Is not unheard of to have a 25 year old clutch diaphragm spring fail. I had to replace mine. But if the stack height is right, Cable is right, No notches in the center, Your getting proper lift at the center via the rod, than a hard pull is normally a badly routed cable. Is the cable tied down too much? Is it lubed properly? Norton's have one of the best clutches out there.

PKeith, I have the same issue happening with my 1970 S 750, Read the post under "gearbox refurb" from a couple of weeks ago, I have ordered a new diaphram spring as i cant see what else it could be, hopefully it will arrive in a week or two so i will find out then.

I am also going to rebuild gearbox while i have it apart. My kickstart end play is a good quarter of an inch but i never slip out of gear

Rob -

Let me know if things are different with the new diaphram spring.

I also noted in notes on OldBritts.com that Fred suggests adding another drive plate to the top of the stack. he even offers to ship you an assortment of thicknesses (.060, .065, .070, etc.)so you can experiment to find the right thickness, then send the others back for a refund.

Hmmmm.....

Keith I tried adding an extra plate, ( two steel plates first in to the basket ) which put the stack right on the circlip groove, no different, New spring arrived today ,will fit it in the next day or so and let you know,

OK I admit it i am stupid, fitted new diamphram spring , still no quick release of hand lever, back to square one check everything only to find that ever helpful son had noticed lever was a bit loose so tightened the screw for me making the lever bind badly and not release, half a turn counterclockwise and wow, clutch springs back with smooth easy action, problem solved onto the next adventure

When I was much younger, I worked in a car restoration shop. The owner had a sign on the wall:

Labor Rates:

$35/ Hour
$45/ Hour if you watch
$85/ Hour if you help

Reggie wrote; "and the handlebar lever is not damaged on the pivot i. e. is totally free,"

Rockyrob wrote;
"Check ,check and double check , all as above"

I'm glad you've got it sorted at last Rockyrob.

I hope you're going to take the cost of the diaphragm spring outof his pocket money :?:

Thanks for reminding me Reggie Check ,Check, I think it would give me more pleasure to take it out of his hide, I look at it as charector building, since owning a Norton my workshop demenour has definatley improved,

Rob -

If only my solution was as simple as backing off the locknut on the clutch lever. I am still trying to figure out what's going on.

My theory is that the hard clutch pull with its "wrong" feel is related to the gear shifting problem, but in hopes they were two separate issues, I pulled off the gearbox cover to look for possible causes. The clearance between the gearshift pawl and its spring were right where they were supposed to be - so much for that theory.

I am tempted to experiment with the plate stack by adding another plain plate, though I am not sure i can even fit another one in there, under the diaphram circlip.

PS - I came home from work one day when my son was about 10 to find him doing me a big favor with my bike. He had washed it for me and when I arrived on the scene he had the hose shoved way up inside a muffler to wash out the inside. Very helpful!

Keith

Did it have a correct feel before the new cable?
Sounds like acuator arm has dropped when installing the new cable and now you don't have the proper leverage.

Michael -

the clutch was always a hard pull. But recently I started to have shifting problems too, and I think (maybe my imagination) that the clutch pull got harder about the same time.

The actuator arm is in the right position. It has the correct amount of free play. Everything seems to be set up the way it is supposed to be

Keith

Michael -

No it's not the actuator arm. I suspected the arm might have been twisted, bent, or worn so that it was not pivoting properly, so I ordered a new one.

When the new one arrived (by the way the new one - made by Andover Norton - looked like a really crappy casting) I took off the out gearbox cover.

Turns out the old actuator is perfect, as is it's ball, the push rod, and everything else.

The mystery remains unsolved.

And for those who suggested a cable routing, that's definitely not the case. Same problem with the cable running directly from the lever to the gearbox cover, without being routed under the tank - just sitting freely outside of everything, with nice big round curves in the routing.

hmmmmm......

Now it is down to stack height and/or diaphragm spring.

I had acquired a bike awhile back that had a bad feel to the clutch.
It had Barnett plates and an 'easy pull' spring, which it was not.
The spring fingers did not operate smoothly with the center piece.

I corrected the stack height and threw in a stock spring I had, problem solved.

Experiment # xxx, and still no luck with this ..... getting frustrating but I don't give up easily.

I fitted a borrowed clutch diaphram spring today, to see if it made any difference. It didn't. Exactly the same, and mine looks fine on the bench too.

Stuck a feeler gauge in the gap between the pressure plate and the circlip. Only about 20 thou of space there. Can't possibly add another plate to the stack.

Did notice something though. I can move the entire clutch assembly, with chain sprocket around with my hands. It had in and out play and i can even wiggle it a bit. That can't be right!

I have the required shims in behind the clutch center, so what is causing this wiggle room? And could it be related to my hard pull and the feeling that the plates are just not lifting far enough?

HELP

Keith (frustrated but determined) in Encinitas

Are you sure that the clutch release bearing is OK - I had one fail many years ago and it resulted in very peculiar clutch operation.