1934 Norton ES2 clutch drag

Hi Les

Have you checked that the clutch centre nut is tight? If it is slowly loosening off the whole clutch assy will move outwards, increasing the free play on the cable. Just ask George Phillips about this!

Cheers, Ian McD

Hi.

This could be down to wear on the mainshaft bronze thrust washer or the gearbox mainshaft hasn't been shimmed correctly.

First off, check the amount of end-float you have on your mainshaft. I'm assuming all you bearings are in good nick. Remove the clutch, make sure you gearbox sprocket nut is fully tight and push the mainshaft inwards, keep pressure on it and measure the distance with a vernier caliper from the end of the mainshaft to the tip of the sleeve gear. Then pull the mainshaft outwards and measure again. The difference should not be more than 1/32" or 31 thou (the minimum it should be is 8 thou). If it is slightly more than this i.e. 10 thou then it can be shimmed up with a packing washer behind the clutch worm nut pushing the bearing inwards. If it is more then the gearbox will have to come apart. Check the thickness of the bronze thrust washer - it should be 7/32" or 0.219". Maximum permissable wear is 1/16" or 0.0625". If it is OK then you'll have to add shims to the end of the mainshaft between the bearing and mainshaft first gear and/or the sleeve gear and its bearing. Also, these boxes often had shims behind the large main bearing but they often disintegrate. They also sometimes have a dished shim washer (hence the reason to hold press on the shaft when measuring end float) between the first mainshaft gear and the bearing but these too tend to break or go missing.

Cheers,

Ian.

Hi.

As everything warms up, including the gearbox, then any end float present will increase. If this is excessive your clutch will not fully disengage, start to drag, then the plates heat up and so forth exacerbating the situation further. The other thing you could try is strapping the clutch lever in and checking the gap under the pressure plate is even. The manual says you should do the pressure plate bolts up fully. On my Manx this results in the pressure plate not lifting evenly. I use feeler gauges under the plate and adjust the bolts. I put a dab of loctite on the bolt threads. Check there are no ridges on the spring cups too. Having said all this, I really would advise checking the gearbox end float first.

Cheers

Ian.

Hi again.

Try pushing a 12" socket extension bar through the inspection cap hole and gently levering from various angles. When I put my 1960 ES2's case together I always put a smear of RTV along the bottom half with a smear of 'Copaslip' around the top half to help with taking it apart.

Cheers

Ian.

Hi Les,

Try to avoid stopping in gear, i.e. just before you stop, snick the gearbox into neutral, then wait until you are about to take off before you select 1st gear.

This should prevent the clutch plates from generating too much heat.

My 1950s bike with Laydown gearbox and Norton clutch does not like sitting in gear. The clutch quickly heats up and starts to drag.

If you do cure the problem, I would be very interested in hearing about the solution that you found.

Cheers,

Ross.

Previously leslie_youngman wrote:

another point to add just for info is that when started in neutral the rear wheel spins unless I operate the brake so there is drag somewhere in the gearbox as well. It's not significant drag, wheel stops easily enough when brake applied with no impact on engine idle.

will let you know what I find

Les

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That's fairly normal as it's just the oil in the box dragging the output shaft round. As long as, as you say, it stops with the brake easily without stopping the engine it's nothing to worry about.

A tight chain or even tight spots in the chain will pull the clutch over and make the plates rub the inside of the drum causing drag. My modification with oversize rollers helps to resist this.

You always need to finish off adjusting the primary by pushing it forward (ie slightly overtighten then use the adjuster to push the gearbox forward to get the right tension). This is because the pull on the rear chain is more than that on the primary so that tends to pull the gearbox backwards. Finishing the adjustment with pushing the box forward ensures that all the small clearances are taken up.

Hi again Les.

This might be useful sorry about the quality but I had to copy it from a PDF file too large to load on the NOC comments.

Cheers,

Ian.

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That's a very handy little article Ian.

Glad you found the clutch retaining nut to be tight. Ian MacDougal is quite right to note it. My IoM trip this year was almost ruined by that nut being just a tad loose. Let us all know what you find to cure it, Les, as it's a common prob. I have to say that since the application of a size 10 boot on the spanner end on the Island I've had no further probs. George

A great article, Ian. I notice the date of the magazine was my fifteenth birthday! George

Apart from the chain tension and end float suggestions there is another possibility - the plain plates may be distorting as they warm up which will produce drag, although I don't think that alone would account for the increase in free play. I think you mentioned that you haven't replaced the plain ones as they are pretty flat. There may be a world of difference between flat and pretty flat! New plates are thicker than the originals and have a dimpled finish. I think they are less likely to distort.

Cheers, Ian McD

Hi Leslie

Nice bike!

Both my Norton's can suffer with clutch drag if I use the clutch to much. Lot's of traffic is not kind to them!

The most important thing is to make sure you knock it into neutral as soon as possible when stopping and try to avoid slipping it when in traffic.

I've found ATF to be a good oil to put in primary chaincases, might be worth a try - failing that check the plates as people above have mentioned, and maybe bite the bullet and get some new ones. We had a problem a couple of years ago with a Velocette doing exactly what you describe, changing the plates transformed it and it turned out there was a dodgy batch of plates doing the rounds. The wrong material had been used and was swelling up way to much!

I've got the Surflex ones in my Norton clutches, more expensive but well worth it - it's a lovely clutch once it's set up properly.

Good Luck

Andy

Leslie:

Nice bike.

Cannot the speedo cable be made shorter or re-routed such to eliminate the large amount of freeplay?

Mike

Les

Regarding speedo cable run:There are some pictures in thethread started by Ian Taylor about9 below yours on the Singles questions.

I've just realised you say you have a "90 degree input connector" - mine is directly out of the bottom of the instrument. It has an original manufacturer's date marking so I've so reason to suspect it might not be original.

For what it's worth - and it may be obvious - I fix the cable to the speedo before lowering the panel down into place and then fix the bottom end. It's not really practical to lift the panel high enough to disconnect the top if the bottom is still in place. Maybe someone added a 90 degree adaptor just to make it easier to fit? Can't you just removed the adaptor?

Hi Les

Happy to hear you are making progress with the clutch. Just a couple of other suggestions: If a shorter operating arm has helped free the plates it might be worth checking the nipple-pivot dimension at the handlebar end, it should be 1" for these clutches. If later levers have been fitted it might only be 7/8". Going back to your photos it looks like the clutch cable might be a bit on the short side. Lying in front of the oil tank as it does forces a change in direction as it enters the adjuster at the 'box. It would be more usual for the cable to follow the rear guard then pass behind the oil filler before sweeping round to the top tube.

Cheers, Ian McD

Previously David Cooper wrote:

Les

Regarding speedo cable run:There are some pictures in thethread started by Ian Taylor about9 below yours on the Singles questions.

I've just realised you say you have a "90 degree input connector" - mine is directly out of the bottom of the instrument. It has an original manufacturer's date marking so I've so reason to suspect it might not be original.

For what it's worth - and it may be obvious - I fix the cable to the speedo before lowering the panel down into place and then fix the bottom end. It's not really practical to lift the panel high enough to disconnect the top if the bottom is still in place. Maybe someone added a 90 degree adaptor just to make it easier to fit? Can't you just removed the adaptor?

Hi David,

Could you please send me the dimensions of the screws which attach the panel to the tank. I have searched for a supplier with out luck and it seems I will need to make my own.

Thanks in advance, Ian

I think the problem is in your comment 'old type chainwheel with new cork inserts'

The Norton clutch should have Ferodo friction material inserts in the chainwheel, not cork. These inserts are manually fitted to each friction plate. The ones for the chainwheel are thicker than for the ordinary friction plates.

Using cork instead of Ferodo inserts will cause drag

Paul

Previously leslie_youngman wrote:

Hi all.

I have just completed the restoration of my 1934 ES2, see pics if I manage to load them.

I have clutch problems with 'swelling' plates I think. I have a set of new friction plates (painted blue in colour, some of you might have used them) the drive plates are used but good with very little wear and pretty flat. It has the old type chainwheel with new cork inserts.

cheers

Les

Why does cork cause drag and Ferodo doesn't?

George

I've had that "drags when hot" syndrome on mine. I concluded that as the plates and inserts warm up they expand; as they expand they take up more room (natch!) and push the clutch outer plate further away from the mushroom thus giving more free play at the lever and less productive movement on the cable/operating arm.

Great - but how to cure it!!!

George

The Ferodo inserts are much denser, more consistent and more temperature stable than corks and were what Norton fitted back to pre-war days. Even they, though can become loose and alter position.

Ken McIntosh (and maybe others) offers a conversion of the clutch basket to bonded friction discs which is the best way to obtain a clean clutch lift.

Another alternative is to use a later, AMC type clutch which has a plain basket with bonded friction material on the backing plate (and a friction plate in first).

With either of these systems and bonded rather than insert friction plates, the clutch becomes completely consistent in normal use.

A good rough guide to whether a clutch is dragging at all when cold, rather than just the oil in the sleeve gear, is to put the bike in gear with the engine running, hold the clutch in and paddle backwards. This should be quite easy to do with little real resistance. It's more representative of real conditions than simply checking on the stand as the components are under load.