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daveh
Joined: 22 Jan 2008
Posts: 32
Location: Dublin, Ireland
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 Posted: Wed Jun 25, 2008 2:42 pm Post subject: Clutch operation |
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I would be grateful for some advice on a clutch issue. I can select neutral easily from cold but as the engine and gearbox reach normal operating temperature, neutral becomes more difficult to find. I have made the adjustment at the clutch itself as per the manual, then taken up the slack at the handlebar. I have to adjust it to the point where the clutch pushrod is just rubbing against the actuating mechanism to get the required 'lift' to free the plates when hot.
I am using all the leverage at the bar to free the clutch and it engages very close to the handlebar as I accelerate from a standstill. I stripped the clutch recently, and all the plates are flat and were degreased thoroughly. I did the Mark 3 gearbox breather conversion. The clutch centre and hub are OK. Even directly after the rebuild, it was still the same. Is this common on Commandos? Also, I don't feel the lever snap back as it is supposed to. The lever action is reasonable, but from what I have read, it could be better. My clutch has the bronze plates, and it's an 850 Mark 1. I have heard that as the clutch wears, it needs greater pressure to disengage. How do I set up the stack height on a bronze plate clutch? Sorry to ask this as it has been covered before, but it's hard to find some of the relevant posts. Advice would be appreciated. |
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ML
Joined: 29 Jul 2007
Posts: 43
Location: Melbourne, Australia
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| Posted: Wed Jun 25, 2008 7:42 pm Post subject: |
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We experienced something very similar on a Mk3. It all seemed fine on the set up, but then we noticed that the plate and basket splines had wear notches which we had simply overlooked. Filing the waveiness out of them cured the problem. Not a long term cure, but so far hasn't come back.
Mick |
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mwoo
Joined: 24 Oct 2007
Posts: 59
Location: Leamington Spa, Warwickshire, England
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| Posted: Wed Jun 25, 2008 9:58 pm Post subject: Clutch |
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I am interested in the "Mk3 Breather Modification" mentioned - what is this ?
Cheers. |
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L.A.B.
Moderator
Joined: 20 Nov 2004
Posts: 1842
Location: Norfolk, UK
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| Posted: Wed Jun 25, 2008 11:29 pm Post subject: Re: Clutch |
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| mwoo wrote: | | I am interested in the "Mk3 Breather Modification" mentioned - what is this ? |
This is the breather modification: http://www.oldbritts.com/12_065199.html |
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mwoo
Joined: 24 Oct 2007
Posts: 59
Location: Leamington Spa, Warwickshire, England
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| Posted: Wed Jun 25, 2008 11:39 pm Post subject: Gearbox Breather |
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| Thanks LAB |
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L.A.B.
Moderator
Joined: 20 Nov 2004
Posts: 1842
Location: Norfolk, UK
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| Posted: Wed Jun 25, 2008 11:49 pm Post subject: Re: Clutch operation |
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| daveh wrote: | | I have to adjust it to the point where the clutch pushrod is just rubbing against the actuating mechanism to get the required 'lift' to free the plates when hot. |
It could be worth checking that the lifter assembly parts are not worn, especially the roller, sleeve and pin? If there's any sign of wear, then I would replace them, along with a new operating lever. Check that the operating lever movement is exactly in line with the cable. It may be necessary to set the pushrod adjuster a little tighter than the manual recommendations, but there must be some freeplay.
| daveh wrote: | Also, I don't feel the lever snap back as it is supposed to.
My clutch has the bronze plates, and it's an 850 Mark 1. I have heard that as the clutch wears, it needs greater pressure to disengage. How do I set up the stack height on a bronze plate clutch? |
An option could be to change the bronze plates for fibre ones, and then adjust the stack height?: http://www.oldbritts.com/ob_clutch_info.html
Your handlebar lever shouldn't really lag behind when you release it? So the cable may need re-routing or lubricating -or replacing? |
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daveh
Joined: 22 Jan 2008
Posts: 32
Location: Dublin, Ireland
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| Posted: Thu Jun 26, 2008 1:37 pm Post subject: clutch operation |
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| Thanks for that L.A.B. I made sure to check the alignment of the clutch actuating lever with the cable, as per the manual, and the roller and lever seem in good nick. I probably wasn't explaining myself well but there is no lag when I release the clutch lever at the bar. When I pull the lever, there is no 'over centre' feel as the heavy fingers of the diaphragm are released, followed by the lighter fingers, if you see what I mean. Are the fibre plates known to be better than bronze? And is the reduced weight better for the gearbox? |
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L.A.B.
Moderator
Joined: 20 Nov 2004
Posts: 1842
Location: Norfolk, UK
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| Posted: Fri Jun 27, 2008 12:07 am Post subject: Re: clutch operation |
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| daveh wrote: | | there is no lag when I release the clutch lever at the bar. When I pull the lever, there is no 'over centre' feel as the heavy fingers of the diaphragm are released, followed by the lighter fingers, if you see what I mean. |
Right, I see what you mean, my clutch goes over-centre when the ball end of the lever is about half an inch away from the grip. I don't find the lever force excessive, so haven't bothered trying to 'tune' the stack height.
| daveh wrote: | | Are the fibre plates known to be better than bronze? And is the reduced weight better for the gearbox? |
Some owners have remarked that modern fibre plates are better, (less slip & drag) and there could be a slight weight reduction, but I'm not sure if it is a significant amount? I'm still using the bronze plates and they seem to work well enough if they are cleaned occasionally. |
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marinatlas
Joined: 04 Nov 2007
Posts: 35
Location: France-St malo
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| Posted: Fri Jun 27, 2008 2:18 am Post subject: |
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Take it easy boys.......I am sure BDM spirit is somewhere looking at us!
clutch weight should awake him.....that's a joke , just because I am missing him and his knowledge. Pierre |
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hewhoistoolazytologin
Joined: 18 Mar 2005
Posts: 671
Location: deep in the woods of Schnitzelland
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| Posted: Fri Jun 27, 2008 2:40 am Post subject: |
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| Butting in here...I know...but a clutch that gets grabby when hot...sure the old push rod seal conversion isn't called for? Another point is the leverage in the tranny where the cable hooks up to that little lever. If the bolt is worn out it will make for lousy leverage. Grooves in the Clutch center, as mentioned, causes the plates to not want to separate. My guess is the Dyno Dave trick though. |
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daveh
Joined: 22 Jan 2008
Posts: 32
Location: Dublin, Ireland
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| Posted: Fri Jun 27, 2008 5:01 am Post subject: clutch operation |
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| I take from LAB that I can stick with the bronze plates, provided they are cleaned periodically. I suppose it's no harm to install the clutch pushrod seal, in addition to the Mark 3 gearbox breather modification. And also, I should check that bolt on which the roller pivots in the clutch actuating mechanism. |
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jimbo
Joined: 24 Sep 2004
Posts: 32
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| Posted: Fri Jun 27, 2008 6:21 am Post subject: |
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| I just finished my primary and trany rebuild. I degreased the clutch plates and roughed them up on the cement because I had some high rpm slippage. Slippage cured . I noticed my stack was not quite up to the clip groove and now I'm wondering as you if I needed to mix up some parts to get a thicker stack. I have a heavier clutch pull than I have seen and like. I can find neutral hot and cold. Perhaps you have something in your gearbox binding?(main or lay shaft gets hot and grows ,binding up not allowing the gears to be thrown) or a pawl spring that needs a little attention. Or ,I just thought of this, your primary chain is probably too tight, running OK when cold but when the primary housing expands faster than the steel chain it pulls on the clutch basket and binds up the trany inputs and outputs. |
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scim77
Joined: 21 Mar 2006
Posts: 84
Location: West Sussex, England
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| Posted: Fri Jun 27, 2008 11:53 am Post subject: |
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If your clutch lever feels heavy and never reaches the easier 'over-centre' inversion point which a diaphragm should do, then I suspect you need more stack height on the plates.
Check that all previous suggestions are ok and that the little roller toggle arrangement where the cable hooks into the gearbox is correctly built up and is in line with the outer cable entry position on the cover.
Hot drag and difficult neutral selection is also aggravated by a primary chain which is too tight, or excess end float in the kickstart shaft. Aim for 5 to 10 thou end float max. You can shim this shaft using rear isolastic shims. |
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daveh
Joined: 22 Jan 2008
Posts: 32
Location: Dublin, Ireland
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| Posted: Sat Jun 28, 2008 4:36 pm Post subject: clutch operation |
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| Thanks Jimbo and Scim77. The easier clutch pull needs a check on stack height, which I will correct if necessary. I took great care to tension the primary chain correctly, so I know it's not too tight, but I wasn't aware it affected neutral selection. I had the bike out today, so after a good run, when neutral was hard to select, I disengaged the clutch with the engine off, in first gear. With the adjustment at the lever to the point where there is almost no clearance in the clutch actuating mechanism, the bike would freewheel only when the lever was almost at the bar (less than 1 cm away). I have an average sized hand, and the lever is almost at my fingertips when at rest, so it seems like I'm not getting the required lift to free the plates. I cleaned the plates thoroughly about 600 miles ago. Does that point to the actuating mechanism, as LAB and others have remarked? |
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Rockyrob
Joined: 05 Dec 2007
Posts: 86
Location: Queensland Australia
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| Posted: Tue Jul 15, 2008 3:14 pm Post subject: |
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Thanks for the replies , . I had to this point assumed it was the original bearing but having just pulled the clutch apart and found 5 friction and 4 plain plates i now wonder what other mods internally have been done as the 750 only had 4 friction and 3 steel according to my reading. If its been upgraded to a 850 clutch maybe the bearing has been done also. If i have to pull it apart to check its the same as replacing job wise i guess so thanks in advance for the assistance i will rewuire:),, Theres about six weeks of winter left here so i better make a decision ASAP
Cheers |
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The Unapproachable Norton Commando
At the end of 1967 the Norton Commando was announced.
The Norton Commando was greeted with a certain amount of scepticism because on first sight the commando appeared to comprise of the old Norton Dominator twin cylinder engine mounted at an inclined angle in a set of new cylinder parts.
It was not realized that the new Norton Commando Isolastic method of engine suspension damped out all engine vibration and produced a machine which had uncanny smoothness for a vertical twin. In due course the critics were silenced and the Norton Commando had the distinction of being regarded as the first of todays so called superbikes. There can be little doubt that the original design concept of the Norton Commando has proved correct, since comparatively few modifications of any real consequence have been made since production commenced during 1968.
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It is more deserving to give credit to the Commando itself, for after all these years it continues to be respected. The original Commando designers like John Favill are those who deserve the credit for developing this incredible motorcycle.
The Norton Commando Roadster and Interstate of the late seventies, never died. Although the Norton Villiers factory dispersed the tradition lived on. Today Kenny Dreer in the USA is developing the new 952 CC Norton. What a great looking bike this is, and its engineering is still based on the original layout. It will be interesting to see how the new 952CC Norton does in todays tough motorcycle market. One thing is for sure, I would own one if I could afford it.
