Clutch Drag

dynodave said:

What kind of gearbox shifter mechanism maintenance or work has been recently done... or NOT been performed that is being overlooked.... just thinking out loud?

Added: we seem to have moved from clutch drag to hard to find neutral as the residual symptom

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In theory you are correct and I do not argue about that only after an initial assembly of clutch components we expect things to work as before without having the cable adjuster on the stop and with no play (since my ownership it has always been like this).
I did overhaul the gearbox two years back due as you Americans say it having 'that old bus sound' (I could just imagine it being yellow and full of kids honking down the road)
and replaced several bearings, gears and bushes.
At that time I had not found this forum and had been instructed by a well known Norton dealer in England to give it some STP.
That did help but was no remedy so again STP this time STOP TAKE PICTURES and real help came.
The actuator arm looked fine as did the roller.

As I have never ridden anybody else's Commando let alone a Mk III there is no way for me to compare, without a doubt the gearbox is slicker than a T140 and almost matches that of a bevel Ducati but toggling neutral is not always as successful.

Sorry if I am going on a bit now but in my younger days I rode a T140 and a mate of mine I remember also moaning that he always had to select neutral as he rolled to the lights, now I didn't want to digress.

Thank you for your help
John

L.A.B. said:

There were three versions of alloy Commando clutch lever.

062249 ('71)
062702 ('72 - '74 and replaces 062249)
065878 (850 Mk3).

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Can I ask what are the differences are between 2702 & 5878?

olympus said:

Can I ask what are the differences are between 2702 & 5878?

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I'm not absolutely sure as I don't have an example of 2702 to compare with 5878.

The nipple hole of 5878 looks closer to the pivot casting joint and the lever shape is slightly different.

062702

065878

I might contact AN on Tuesdays to ask
If you cast your mind back a couple of Months i was having an issue (which i still have) with the handle bar adjuster being wound almost fully out... even with new cable, internal cam, roller etc
I also have a drag problem so after initial road test in a couple of week i will start with clutch pack height.
But i also have the clutch lever extender and 5878 lever.... and i agree the nipple hole is closer to the edge

dynodave said:

I am baffled as to why 12.5mm of cable pull is inadequate.

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Around 3 - 4mm of cable travel appears to be 'lost' between the handlebar lever and gearbox actuator as my Mk3's actuator movement I'd estimate to be about 0.6"/15mm for 19mm travel at the handlebar lever giving 0.126" pushrod/spring lift.

dynodave said:

That represents the WHOLE cam profile shown here of .500". That is 2-1/2 times the pull required to make the clutch disconnect.

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....For an Atlas or similar type clutch where the pushrod directly acts against the pressure plate therefore all pushrod movement is clutch 'lift', I would agree.

The Commando clutch pushrod, however, lifts the diaphragm spring at its centre but the spring bears against the pressure plate thrust ring at approximately the mid-point between the spring centre and the periphery where there is zero spring lift, so as I see it, and although I don't have any figures, the actual 'clutch' lift is only going to be approximately half the 'pushrod' lift.

dynodave said:

131" is full travel clutch movement of which only .050" should be required to give complete clutch disengagement.

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If 0.131" (3.32mm) only lifts the clutch by about half that amount then the "2.4 - 2.1mm" quoted by Woody850 is likely to be inadequate in my opinion.

dynodave said: I am baffled as to why 12.5mm of cable pull is inadequate.

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L.A.B. said:Around 3 - 4mm of cable travel appears to be 'lost' between the handlebar lever and gearbox actuator as my Mk3's actuator movement I'd estimate to be about 0.6"/15mm for 19mm travel at the handlebar lever giving 0.126" pushrod/spring lift.

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I do not use plastic lined cables! A generous cable routing of a plain steel bowden compression loss may not be as bad as the tight bend platic lined cables?

All commando clutch diaphragms have contact with the pressure plate half way to the edge. For me All measurements are from the clutch center adjuster nut. Adding the geometry is only doing a shell game to complicate.
However all bets are off based on these new style circliped diaphragms. My research and data are only for the original style diaphragms.

In my rather large pile of 3 styles of clutch plates, the number of thick or thin friction plate wear is very minimal. For this reason I find 1/4 (.0125") turn out on the adjuster to be quite adequate for many many miles of wear before the clearance is theoretically taken up, actually I have NEVER found a clutch with a closed up adjuster.
At the handle bar I have quite loose clutch cable adjusters . It keeps the friction release point close to the bar.... and easily adjusted if more over center effect is wanted.

dynodave said:

I do not use plastic lined cables! A generous cable routing of a plain steel bowden compression loss may not be as bad as the tight bend platic lined cables?

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That's up to you, but according to your figures, the 0.6" cable movement at the actuator that my Mk3 has is more than adequate.

dynodave said:

All commando clutch diaphragms have contact with the pressure plate half way to the edge.
For me All measurements are from the clutch center adjuster nut.

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Yes, but your comparison of Atlas to Commando pushrod lift figures suggests the two clutches are directly comparable when in fact they aren't.

dynodave said:

Adding the geometry is only doing a shell game to complicate.

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As the actual Commando clutch plate lift has to be considerably less (~50% less?) than the pushrod/spring lift then it can't simply be ignored.

Edit: I'm sure the lift could be measured at the spring mid-point position where it is in contact with the pressure plate ring. No need for geometry.

L.A.B. said:

That's up to you, but according to your figures, the 0.6" cable movement at the actuator that my Mk3 has is more than adequate.

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Agreed it is adequate and 2-1/2 times what is needed for complete clutch disengagement. you only .050" movement of clutch center

L.A.B. said:

Edit: I'm sure the lift could be measured at the spring mid-point position where it is in contact with the pressure plate ring. No need for geometry.

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Basic clutch center measurement only needs adjustment cap removal....KISS method to get the same results...
or on regular commando remove foot peg, remove primary cover, oil mess, + added work for MKIII + gasket +11 screws !

Alternately you could just use the adjust screw, (from firm) tighten 1 turn (20TPI) for .050"lift, 1-1/4 turn for .0625" if your clutch is not totally free then there is a problem...In neutral your kicker spins freely.

Is this so hard?

dynodave said:

Basic clutch center measurement only needs adjustment cap removal...

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Yes, I know, and as I've already demonstrated in this thread if you'd care to check but that's not what I'm talking about here but about measuring actual clutch plate lift.

dynodave said:

Basic clutch center measurement only needs adjustment cap removal....KISS method to get the same results...
or on regular commando remove foot peg, remove primary cover, oil mess, + added work for MKIII + gasket +11 screws !
Alternately you could just use the adjust screw, (from firm) tighten 1 turn (20TPI) for .050"lift, 1-1/4 turn for .0625" if your clutch is not totally free then there is a problem...In neutral your kicker spins freely.

Is this so hard?

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No, as I wasn't referring to clutch spring centre lift. Once again what you are referring is clutch spring centre lift which can't be the actual lift at the pressure plate and what I was referring to.

My Mk3's clutch with 0.126" lift (therefore not far off your quoted 0.131" so no apparent "problem" Edit: and with some free-play at the 'bar lever) but it doesn't begin to free off until around 0.095" - 0.100" spring lift, not 0.050".

Even the best spiral wound bowden cables with a few bends in its run will compress under load.
I make my own clutch and throttle cables with linear lined outer cables.

dynodave said:

(from firm)

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L.A.B. said:

My Mk3's clutch with 0.126" lift (therefore not far off your quoted 0.131" so no apparent "problem"

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Makes me wonder if your clutch center bearing is sloppier than normal ?
"from firm" takes out the clutch center bearing side play where it starts to restrain the basket, also possibly the main shaft ball bearing that also restrains both the main shaft and clutch.
I got nothing else?

dynodave said:

Makes me wonder if your clutch center bearing is sloppier than normal ?
"from firm" takes out the clutch center bearing side play where it starts to restrain the basket, also possibly the main shaft ball bearing that also restrains both the main shaft and clutch.

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No evidence of any of that. Personally, I'm sceptical that your 0.050" spring lift figure is realistic in practice Edit: I could quote 'Beltdriveman's views on the subject?

L.A.B. said:

There were three versions of alloy Commando clutch lever.

062249 ('71)
062702 ('72 - '74 and replaces 062249)
065878 (850 Mk3).

Click to expand...

The correct parts came today and I have installed them.
It is unbelievable to say that is where the whole cause came
from, not enough pull at the lever.

I say a very great thank you to all for your help and a special thank you to LAB for pointing me in the correct direction.

John

For such a simple machine , the clutch on the Norton is the most intricate & annoying to set up....
And i think now i understand why my clutch may be dragging ....well lets say just awful
I pulled it apart yesterday for investigation after reading several posts & specifically the Atlantic Green article on clutch stack height
Now i would appreciate your input
Mine is a 72 build and fitted to the clutch are
4 friction plates at around 0.124 3.15mm.
4 steel plates at 0.079 2.00mm
Pressure plate at 0.236 6.00mm
Stack height all components lightly clamped in vice 1.050 26.69mm
which is nothing like what Atlantic green state. at 1.167
With circlip installed only an levered outward i get 26.60mm 1.047. so the aperture for the stack concurs.???
Then studying AN diagrams for the 72 states 4 friction & 3 steels, this is clearly not right?
Then when i looked at the 71 it shows an additional removable pressure plate in the base of the clutch basket held in with rivets so i's thinking that Atlantic green take this in the calculation.
Also AN are stating 4 friction discs & only 3 steels for the 71
So you can imagine i haven't got a clue what I've got and what I'm suppose to have
Your assistance would be appreciated

olympus said:

Mine is a 72 build and fitted to the clutch are
4 friction plates at around 0.124 3.15mm.
4 steel plates at 0.079 2.00mm
Pressure plate at 0.236 6.00mm

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What you have are 4 'thin' friction plates from a 5-plate clutch instead of four 'thick' plates and 4 steel plates when there should only be 3 steel in a 4-plate clutch.

olympus said:

Then studying AN diagrams for the 72 states 4 friction & 3 steels, this is clearly not right?

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That is correct for the 4-friction plate clutch = 4 friction, 3 steel and 'thick' pressure plate.

olympus said:

Then when i looked at the 71 it shows an additional removable pressure plate in the base of the clutch basket held in with rivets so i's thinking that Atlantic green take this in the calculation.

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The removable clutch backplate was fixed in later clutch drums and is included in dynodave's calculations.

olympus said:

Also AN are stating 4 friction discs & only 3 steels for the 71

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That is correct as the backplate isn't a normal 'steel' plate.

Edit: Although the backplate is available separately, the current drum/chainwheel comes "C/W (complete with) backplate".

Thanks very much Les
So i should have..
4x 3.6mm friction plates... 14.40mm
3x steel plates @ 2mm 6mm
Pressure plate @1/4" 6mm
26.40mm in total...

olympus said:

Thanks very much Les
So i should have..
4x 3.6mm friction plates... 14.40mm
3x steel plates @ 2mm 6mm
Pressure plate @1/4" 6mm
26.40mm in total...
View attachment 16517

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Approximately, yes so it looks as if the plates have been mixed and matched to increase the stack height.

Note that dynodave's stack height measurement includes the full height of the pressure plate to the pressure ring, not to the plate edge (as Old Britts measure it).

"750cc:
Friction plate is: 0.145”
Plain plate is: approximately 0.080"
Pressure plate is: 0.225”
Total clutch plate thickness (4 friction, 3 plain and 1 pressure) is: 1.045”
"

I'll also order a 3mm steel to take up the minor "differences" if needed I'll have the pressure plate lightly skimmed to get the correct stack height

olympus said:

For such a simple machine , the clutch on the Norton is the most intricate & annoying to set up....

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I dunno about that, have you ever setup a Velocette single clutch ?

olympus said:

I'll also order a 3mm steel to take up the minor "differences" if needed I'll have the pressure plate lightly skimmed to get the correct stack height

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Yes, if you replace one of the steel plates with the 3mm plate then, hopefully, it will lighten the clutch action but not enough that the clutch begins to slip.