Clutch action

PJL · May 4, 2010

Question - is there any way to alter the action of the standard clutch operating mechanism such that it is more progressive, like other bikes? Preferably without spending loads on a hydraulic conversion.

The clutch works fine, no slip or drag, but it bites suddenly over a very short travel, it is quite non-linear, compared with my other bike and all other bikes I've owned. This can make slow speed manoeurvring quite tricky at times.

Thanks, Phil.

swooshdave · May 4, 2010

How light is your clutch pull?

PJL · May 4, 2010

quite light. Only slightly heavier than my MZ TS250.

Phil.

swooshdave · May 4, 2010

Maybe clean the plates? Or at least give them a good inspection?

PJL · May 4, 2010

Done. Plates in good order, clean. No major oil contamination (still using chain, with ATF at right level). No difference ever since I bought it two years ago. Interestingly the travel is much shorter than the MZ and it bites just as you feel the diaphragm spring going over centre.

tpeever · May 4, 2010

PJL said:
Question - is there any way to alter the action of the standard clutch operating mechanism such that it is more progressive, like other bikes? Preferably without spending loads on a hydraulic conversion.

The clutch works fine, no slip or drag, but it bites suddenly over a very short travel, it is quite non-linear, compared with my other bike and all other bikes I've owned. This can make slow speed manoeurvring quite tricky at times.

Thanks, Phil.

What kind of clutch plates are you running? My bike has the bronze plates and they seem to work really well but I don't have anything to compare to. I have no slippage and both the pull and engagement are very smooth and progressive. My Commando clutch is the best of any of my vintage bikes by far and I daresay is almost as nice as the hydraulic clutch on my 96 Thunderbird. I think it's all in how you set it up (proper stack height) and maybe also the kind of plates you are using. I have never tried Barnett or Surflex plates, but I believe some folks here have written that the engagement with one or other of these brands can be very harsh.

PJL · May 4, 2010

Ah, perhaps good point. I'm running the Surflex plates.

What I was wondering was whether the shape of the clutch operating lever on the ball bearing is such that it is not actually a linear action. I read somewhere that the hydraulic clutch operation was more akin to that on other bikes, which got me wondering.

kraakevik · May 4, 2010

Some people years ago substituted Atlas clutch operating levers to lighten the clutch pull--might be worth checking the parts book to ensure that you have the Commando item--good luck

Tim Kraakevik
kraakevik@voyager.net
Three Commandos

daveh · May 4, 2010

PJL said:
What I was wondering was whether the shape of the clutch operating lever on the ball bearing is such that it is not actually a linear action. I read somewhere that the hydraulic clutch operation was more akin to that on other bikes, which got me wondering.

I fitted a new operating lever recently (from Andover Norton) and ever since then, the clutch action has been the same as yours — very abrupt. (I made sure to order the Commando rather than the Atlas lever.) I live with it, but it's not ideal. I may re-fit the old actuating lever. I would like to see how a new old stock lever would work. We already know that quality control and precision of some new Norton parts is poor, and that could be the problem in this case.

Some Commando clutches with the standard cable actuation have a beautiful, light operation and don't seem too abrupt. I will persevere with the stock system for the moment and try to improve it.

Dave

swooshdave · May 4, 2010

daveh said:
I fitted a new operating lever recently (from Andover Norton) and ever since then, the clutch action has been the same as yours — very abrupt. (I made sure to order the Commando rather than the Atlas lever.) I live with it, but it's not ideal. I may re-fit the old actuating lever. I would like to see how a new old stock lever would work. We already know that quality control and precision of some new Norton parts is poor, and that could be the problem in this case.
Dave

It would be very interesting to see the new next to the old.

ML · May 4, 2010

Have you checked the centre for notched splines? This is common cause of jerky clutch action.

Mick

tpeever · May 4, 2010

PJL said:
Ah, perhaps good point. I'm running the Surflex plates

I think those are the ones that are supposed to be pretty aggressive. The point about clutch rod actuating lever is interesting. Never thought about that but I suppose aftermarket parts could be a bit off and make a large difference. Fred Eaton at Old Britts mentions in his gearbox rebuild notes to make sure that the actuating lever lines up with the cable hole in the outer case but I think this has more to do with ease of clutch pull rather than how it engages. Suppose they could be related though. Have you checked the stack height of the clutch plates? This is also supposed to be critical to ease of operation and may be related to rate of engagement. Old Britts has a good technical article on it I think.

acadian · May 5, 2010

I replaced the standard 750 set up in my bike with the an 850 pressure plate and 5 Barnett friction plates this past winter. With the addition of the Comeau clutch rod seal I also switched to running ATF in the primary. I've noticed a significant improvement both in terms of clutch pull and complete absence of dragging. I think bringing the stack height up is what did the trick, all in all a relatively simple upgrade.

Pressure plate thickness difference:

5 Barnett plates installed:

Clutch rod seal installed:

L.A.B. · May 5, 2010

PJL said:
What I was wondering was whether the shape of the clutch operating lever on the ball bearing is such that it is not actually a linear action.

There's some info on the Atlantic Green website: http://atlanticgreen.com/ndnsclutch.htm = Atlas actuator.

PJL · May 5, 2010

Thanks for the ideas. As per normal this forum is excellent.

A couple of things to consider, either

Alternative plates - perhaps Surflex too grippy

and/or

Atlas arm - according to the graph on Atlantic Green this is linear versus cable pull, whereas the Commado is not; plus the extra mechanical advantage means more handlebar lever movement for same clutch pushrod movement therefore there will be more 'feel' (as with alternative master cylinders for the front brake).

Thanks, Phil.

Clutch action

PJL

swooshdave

PJL

swooshdave

PJL

tpeever

PJL

kraakevik

daveh

swooshdave

ML

tpeever

acadian

L.A.B.

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