classic motorcycle forum

I managed to get an hour in the shed on Sunday, and the rest of the clutch bits had turned up from Andover Norton.

New, (straight!) studs


Adjuster screw and locknut


The first thing in the clutch assembly (after the rubbers and the outer plate) is a tiny bit of "anti-centrifugal grease" on the clutch bearing.... I couldn't find any information on what constitutes "anti-centrifugal grease", so I dug out the high-temp lube I use for brake pads etc.  I'm going to use an extremely small amount, so I figure that all it needs to be is capable of withstanding high temps and not flinging.

The bearing "inner" is the outer diameter of this plate:


Told you I wasn't going to use much.... (actually I used twice that...)


Bearing half-assembled


Studs into the clutch body: they're keyed to semi-squared holes in the bearing race plate so they don't rotate.


Assemble the rest of the body, and don't drop it....




BUGGER!


Try again.
Lastly fit the stud nuts on the back


Clutch body onto gearbox layshaft with washer, lockwasher and big nut


Big nut is the same size as a spark-plug


Again, without having the proper clutch holding tool, I have to resort to using the rear brake to lock the layshaft (via the final drive and gearbox)


I bet myself I could get the stack on in one go.... YAY!


Then I freed off the clutch cable as far as it would possibly go to give myself plenty of slack to work with while getting the setup right.  Ideally, the lever in the gearbox needs to be "over-center" so that the cable pulling it has plenty of room to work.  That means the lever need to be as far away from the gearbox inner as you can get it.


Lots of slack...


Even more slack - from freeing off the handlebar-lever adjuster


The push rod is now a "long" way into the layshaft when "at rest"


And the lever is as far "out" as it will go (probably too far tbh!)


Then fit the pressure plate, spring cups, springs, spring nuts.  The advice is to screw the spring nuts down until they are "flush"


What is supposed to happen next is that you adjust the screw on the pressure plate and the clutch cable adjusters so that although you have a bit of slack (either 1 or 1/2 turns back on the pressure-plate adjuster: advice varies) to allow for thermal variation, and the clutch lever has a nice pressure on the clutch.  Bearing in mind that the push-rod lever needs to be "over-center" and not fouling the inspection cover.

However... to get any where near that state, I had to screw the adjuster screw in so far, that the lock-nut wasn't going to work: even this wasn't engaging the push-rod.


Obviously, with a pressure plate that's about 1/4" deeper than I had before... I need more length in the rod (ooer), or some other way of taking up that gap in the mechanism.

At least enough to give the locknut a fighting chance... It should look like this.


Obviously it took me a few minutes to puzzle that out though, I thought I'd gone mad.

The last thing I did was pull the push-rod out again... and it's covered in oil.


Which confuses the hell out of me - I'm sure I put it back in clean, and the oil is fresh clean stuff, (obviously, since I changed the oil) so - given that the layshaft tube is much higher than the oil-level in the gearbox and the mods I've done are supposed to stop this... the only conclusion is that my mods didn't work. BAH!

I may look at fitting a larger diameter breather , or possibly just drilling out the jet that's fitted (off the gearbox, obvs).  but the sheer amount of oil on the layshaft is really confusing to me.  The way the oil supposedly gets in there is a "oil-mist" when the box is hot and the internal pressure pushes the air/oil mist in there out of whatever exits it can find: the clutch cable is one exit, the push-rod-tube is another, and the blow-hole on the original inspection cover is a third. The idea of fitting the extra breather is to increase the number of exits and so reduce the propensity of the oil-mist to  get where it shouldn't (down the push-rod-tube!).

These clutches do normally, ie, by design, run in an oil bath (the original primary cases on Nortons contain an amount of oil (Not sure huow much, and it seems ATF is preferred, makes sense), mainly to lube the primary chain, so any gearbox oil lost down the push-rod-tube probably isn't really noticeable.  But I'm running this clutch dry (although I think it's got plates that "should" be ok runing wet), so the oil seepage is a lot more noticable, and I was thinking that it may have been what caused the slipping - although I'm beginning to wonder if the oil seepage was just incidental and not the main cause of the slippage.


So, steps in the right direction, and yet more choices to make.

Regarding the push-rod, I'm thinking that tbh, the easiest way to fix this is going to be a longer pressure-plate adjuster screw, so I'll be taking measurements and seeing what I need to find to achieve that.   
Oddly - ther appears to be 2 options for this, but I've only found this reference in one place (so far).

040360: Adjuster, in press. plate. All. Short (5/8”).
061179: Adjuster, in press. plate. Long (7/8”) Norvil, Dom, Comm

So - I'll look into that.

Some advice I've read is to put a 1/4" ball-bearing down the tube as a "spacer/extender", and I may look into that if I can find one in all the junk I've got.  There's already a ball-bearing as part of the push-rod-lever :


Again - an option.

So, plenty to keep me busy....

Still waiting for the new clutch hub to arrive, but some other bits turned up.

New pressure plate is 0.915" "high" so a good 0.2" higher than the old one, should be good.


new rubbers - they're "shorter" than the originals, by about 5mm~ish but I can't really see a problem there, they should still do the job, they're captured on both "ends" of the clutch body so it should be fine.


I also got some new stud nuts so spent an hour or so just spinning a die up and down the stud threads to clean them up.  If you can spin a die down a thread just using your fingers then you're not going to be damaging the thread (unless it's utterly kaput):


Also did the spring nuts, again, if you can spin it down with your fingers, then the thread is correct and you're not cutting it anew.


Then I went looking for a 1/2" bolt or stud for the new pressure plate.... because it's a got smaller hole for the adjuster grub-screw!!


Annoyingly I could find anything at all (well, there's a couple of old bits of knackered stud... but: ) and also not sure what the thread is: so - will likely just order something that is guaranteed to fit from the same supplier.

hey ho....

On your pic of 21st August it appears that it would be possible to screw the clutch nuts down a bit tighter. Have you tried that or do the springs become coil-bound?
Did your dad have the bike running satisfactorily or was the clutch always problematic?
I've had bikes in the past where the clutch springs have measured up OK but still been useless. I suppose that comes with people using what they have rather than buying something known to be suitable for the power expected to be transmitted.

While balancing the clutch springs once or twice they did get screwed in further, however I think the cups were bottoming out. It would certainly explain why I could see the pressure plate moving outward while pulling the clutch lever, and one of the cups was stationary until the pressure plate had moved a sixteenth or so.

From memory the clutch has always been ok, but I wasn't always privy to all the information from the riding the bike had. (Track days etc). It does follow the"philosophy" of the bike's entire build that the clutch would be built up from random found parts that didn't necessarily all match up correctly.

I've got proper pre-63 pressure plate on order, and a line on a replacement hub, so at the moment just waiting for things outside my direct control to happen.

A 12" coarse file, which has a name that the site thinks is not ok to publish.

Leon

Ah yes - the good old illegitimate offspring file.  Gotcha.

Last night I made my (poor) excuses and got out into the shed again.

I pulled the clutch apart and put the plates into some petrol:



While I tried to get my head around this flaming washer.  The local JAP man, who races JAPs in cars and bikes, and has a Manx engined F500 car, which uses a Norton gearbox and clutch, told me that there SHOULD be a washer between the clutch and the gearbox, and (after some detailed discussion) imparted the knowledge that is should be sittingon the OUTER shaft, not the INNER shaft - the gearbox output and input shafts respectively.

NB: the gearbox input shaft rotates INSIDE the output shaft (they rotate in the same direction, but at different speeds).

This mystical washer, according to local JAP man, should sit on the OUTPUT shaft and essentially serves (it appears) to ensure an offset between the clutch and the gearbox output sprocket.

The thing is... this makes no sense to me at all.  Because the clutch has a splined fitting on the end of the input shaft, and that fitting is both tapered, and has a solid stop.  If you do the clutch up tight (without the washer), there IS an enforced clearance between the back of the clutch, and the end of the output shaft.  I simply can't see the need for a washer, the clutch can't bind to the end of the output shaft.

... and besides - if the clutch was NOT supposed to go up tight on that taper, and wedge itself in place under the nut.... WHY would everyone be selling a specialist "Clutch Removal Tool" specifically for pulling the damned clutch OFF that taper??  :wtf:

I pulled the clutch back plate off and fitted the body of the clutch by itself onto the gearbox input shaft:


It's not that easy to see - but the washer is free to rotate with the clutch body tightly screwed on:
https://youtu.be/yYCOc3h9h3A

So - why do I need a washer there???


When the clutch back plate is fitted, and the stud nuts are in place - that washer fouls the stud nuts (it's worn them away in part - as you'll see later - which can't be right).

I cleaned up the studs and the nuts :


Took the race plate and the roller bearings out (yes they went everywhere, and yes I swore a lot, and yes I lost one .... found it again eventually...)



The rubbers still won't come out - but at least I was able to have a sort of evaluation of them - they seem pretty solid still, there's some debris in there  - but not a lot really.


Gave the studs a good brassing: (I gave everything a good brassing!)


Failed to count the roller pins propertly ....  twice...



Back plate, race plate and main body



In all honest - I think this is the real problem:


The dogs on the clutch body: which is where the friction plates act* are battered quite badly.



* : power from the engine comes into the clutch via the "plain" chainwheel plate / basket. 
The other "plain" plates are roated because they interlace with the walls of the basket
So - the "plain" plates are the "driving" plates, carrying the torque from the engine
The Friction plates are pushed against the Plain plates by the springs
The Friction plates are then rotated by that interaction, and
the Friction plates then bear on the clutch body in order to transfer the torque from the engine into the cush-drive rubbers.
The Rubbers then absorb some of that "impact" before passing the torque to the spider in the centre of the clutch,
The Spider has a splined/tapered core which slides onto the end of the gearbox input shaft.

Thus the engine torque is transferred to the gearbox (with some minor losses)

So - the battering that the clutch body gets: would tend to happen when the clutch is "engaged" and the throttle is opened hard and quickly.

Hmmmmmmm.


I carried on with reassembling the clutch body anyway.



These are the battered stud nuts on the back plate, they're a git to work on because they're so flat, knackered, and the back plate has dished areas so getting the spanner on them is very hard (I don't have a 6-sided socket in that size). You can see where the washer has worn away the flats - this is another reason why I don't think the washer should be there.


With the clutch body assembled, and the pressure plate installed:


In this assembly: the pressure plate is NOT hard up against the outer face of the clutch body.  The spring cups HAVE bottomed out, but the plate rattles about (the clearance is less than a millimeter I'd hazard, but it is there)

This is the washer in question sitting on the input shaft... it's NOT large enough to go over the output shaft


Here you can clearly see the output shaft and the input shaft inside it. The pimple sticking out of the input shaft is the clutch push rod which pushes against the underside of the pressure plate (there's a large grub screw in the centre of the pressure plate to allow adjustment: the push rod needs to have enough space to accommodate thermal expansion and have some free play, otherwise the pressure is taken off the plates and you get slippage).



I still don't "get" the washer at all, and I am very concerned that the main clutch body is beyond usage due to those battered dogs/splines.  A new one is around £330 (https://andover-norton.co.uk/en/shop-details-2/15111/clutch-centre-hardended-and-ground), and that would likely entail new plates (~£15 each: 9 of, ) etc etc ..... and you're building up to nigh on new clutch territory.... which is around £830-£950 or so....



Or spend the next 6 months wandering around autojumbles hoping to get lucky, and/or dealing with 2nd hand ebayers and who knows what will turn up in the post....



hmmmm

Current plan is to get a second opinion on the clutch body by taking the dissassembled clutch down to Selsey; and not get too far ahead of myself in the meantime.  The Selsey JAP guy did tell me on Saturday that he spent £400 on something and it was the best £400 he ever spent, but I didn't quite catch what it was that he'd bought, I just know it was something for the clutch!

What confuses me about the worn splines on the clutch body is: that can't have happened suddenly over the first 50 miles or so since I got the engine back in the bike ... it must be pre-existing wear (I'd imagine it would take thousands of miles to do that sort of damage), so why did the clutch only start slipping about 30 or so miles ago?  It's very very obvious when the clutch is slipping, because the kick-start torque goes through the clutch - if it's slipping, the engine will NOT turn over!

Slacked off work this afternoon to take the bike out for another quick spin.

and there was a lot of spinning.... the damned clutch is STILL slipping.  It's obvious in all gears, in first it won't "bite" above a certain engine rev-speed, and in the other gears it simply won't go above 50mph.

So I dragged it's sorry ass back to the shed and had another look.

I screwed the springs in a couple more turns, and made sure they seemed to be "balanced" : ie the pressure plate lifts equally all the way around (as best I could)


I confirmed that there was enough slack in the push-rod linkage, there's plenty.


And then buttoned it back up.  I'm taking it down to Selsey tomorrow whatever (well - unless it pisses it down...), and then we'll see after that.  I think I now know roughly what the clutch "is" (ie which type, and what plates I would need to buy), but there's still a few details I can't tie down, so more research to do. 
I'll look into new plates and new springs, they're the only things that should need replacing.

In the meantime.. the next little project is going to be stripping down the Pilgrim Pump to replace the gaskets: I'm pretty sure that the gasket under this cover plate has gone - there's a definite "snail-trail" coming from it.




"These things are sent to try us..."

I took it out for a spin this evening, and it's running fine, apart from the fact that the damned clutch is slipping at anything over 50mph.

I suspect it's just not setup correctly so will have a play this evening and fingers crossed it'll be good for the weekend.

In good news, it's nigh on oil tight now, apart from that one cover i haven't tried to seal, the timing chain cover.

Incidentally, if anyone is at a loose end and is near the South Coast on Saturday, there's a classic vehicles meet in Selsey, just a suggestion.

.... Later...

So, I think the clutch was indeed badly setup - there was zero play in the lever in the gearbox when I looked this evening.  So I've pulled it apart again, because I was kinda pondering if the plates were badly worn...

however... according to the details I've found: the friction plates should be 0.138" thick, the plain plates 0.080" and the single-sider on the outside (which the pressure plate pushes against) should be 0.110".

I measured them all:


The plates I have are :
Plain plates: 0.080", 0.082", 0.080", 0.082", so they're fine.
The single-sider is 0.111", so it's fine
and the Friction plates are : 0.171", 0.158", 0.172", 0.170"  So, err they're all too thick.


Which makes no sense. (to me at least).  By all rights the thing should be dragging like crazy, not slipping!  :wtf:

I also checked them for flatness on the flatest thing I've got


One or two had a "little" bit of rocking movement. I'll look into how much new plates are and think about it.

SO I did the only thing I can do for tonight....
I buttoned it all up again, and reset it again, trying to follow the manual's instructions as best I could


I think clutch setup is a bit of a black art to be honest....

Oh, and it looks like I was being a bit presumptious about the oil tightness....
[/url]


Hey ho, it's better than it was!