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Heavy clutch operation

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Heavy clutch operation

Posted by ann_nicholls at April 08. 2018

With my 750 Commando up and running beautifully again, it has highligted that the clutch action is really heavy. When I was younger this never bothered me but now I'm an old fart and have arthritus in my hands so I need to to try to make it lighter 'cos it hurts, a lot!

I spoke to RGM as I heard thay do a thicker pressure plate that changes the stack height but unfortunately this is only available for their belt drive system.

The clutch action itself is superb with a nice defined lift point - it's just that I have to apply so much force. Any ideas on how to reduce the effort needed?

Re: Heavy clutch operation

Posted by christopher_winsby at April 08. 2018

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Re: Heavy clutch operation

Posted by john_holmes at April 08. 2018

The springs have varied in force needed over the years with the later ones being stronger, you can get thicker outer plates, no idea why RGMs only fits the belt drives as it just a thick plain plate with an outer profile, you could try adding a single extra plain steel plate but the clutch may slip. Other items to try are following the workshop resetting of the clutch rod clearance but with only a 1/4 turn back off instead of the book value, also get a PTFE lined clutch cable. I did all of this and can use 2 fingers and no slipping with bronze plates.

Re: Heavy clutch operation

Posted by tony_ripley at April 09. 2018

Previously Jem Nicholls wrote:

With my 750 Commando up and running beautifully again, it has highligted that the clutch action is really heavy. When I was younger this never bothered me but now I'm an old fart and have arthritus in my hands so I need to to try to make it lighter 'cos it hurts, a lot!

I spoke to RGM as I heard thay do a thicker pressure plate that changes the stack height but unfortunately this is only available for their belt drive system.

The clutch action itself is superb with a nice defined lift point - it's just that I have to apply so much force. Any ideas on how to reduce the effort needed?

I think there must be a misunderstanding as the thicker plate works with the normal clutch:-

COMMANDO CLUTCH PRESSURE STEEL ADJUSTER PLATE 3MM

PART NO
0607463

RGM Genuine

STEEL COMMANDO CLUTCH PLATE 3MM THICK, ALLOWS THE CLUTCH PLATE STACK HEIGHT TO BE ADJUSTED AND SO LIGHTENING THE LEVER ACTION.  (THE THINNER THE PLATE STACK, THE LIGHTER THE LEVER ACTION).  STANDARD PLATE 060746 IS 2MM THICK.  0607644 IS 4MM THICK.  ALSO SEE 050008, 060749, 061339, 063741, 122M11 & HS0746.

Regards

Tony

Re: Heavy clutch operation

Posted by katherine_scott at April 09. 2018

 

(THE THINNER THE PLATE STACK, THE LIGHTER THE LEVER ACTION).

 

Tony

I would question whether this is always the case ,  on my MK3 I increased the thickness of the plate stack by 1mm, this was achieved by replacing 1 std 2mm steel plate, with 1 of RGM's 3mm steel plates the amount of force required to operate the clutch was noticeably reduced without any slipping clutch issues.

Regards

Katherine Scott

Re: Heavy clutch operation

Posted by gino_rondelli at April 10. 2018

Jem,

Fitted the 3mm plate to Fi's 750 , done the job (also on my mk3) both chain primary's

Re: Heavy clutch operation

Posted by ann_nicholls at April 11. 2018

Hi all, thanks for the replies, especially from Tony that RGM DO sell a thicker plain plate which is now ordered. I've no idea why the chap at RGM told me that I had to buy a belt drive unit to get the benefit of an increased stack height. Also ordered is a new cable oiler so I can make sure that is working OK, although as soon as I start working on the bike I'll measure the current cable and probably just buy a new one anyway, it's been on there for 14 years / 20000 miles.

Re: Heavy clutch operation

Posted by colin_peterson at April 12. 2018

Mention of a cable oiler is ringing alarm bells for me – I'm under the impression that, if you use a PTFE-lined clutch cable, oiling it would extremely detrimental, and could cause heavy clutch operation. Venhill recommend only an internal rinsing with WD40, or at most lubricate with a very light oil, e.g. '3 in 1'. https://www.venhill.co.uk/faq/ – look under 'Do I need to lubricate Venhill's Featherlight control cables?' I've never oiled mine and it's fine. I don't think this aspect of PTFE-lined cables has been mentioned here yet, but maybe you don't have a PTFE-lined cable ...?

Re: Heavy clutch operation

Posted by ann_nicholls at April 13. 2018

Hi Colin, you took me right back to my polymer engineering days (many years ago I was a plastics engineer) and PTFE is a highly crystalline polymer which, in our practical terms, means that nothing much can touch it and why it offers such low friction. So I think when Venhill say you don't NEED to oil it they mean just that. A thick oil would only cause drag on the metal cable inside the outer. It can't affect the PTFE, not much can apart from mechanical wear. But dirt and grit can sometimes work their way into a bowden cable so flushing it out with something light like WD40 or 3in1 would help in those circumstances. However, most of us keep the nipple at the handlbar end greased up so that should trap and stop most of the dirt getting in. Personally, I can tell that my clutch cable is in pretty good shape but the PTFE lining will wear away over time.

The thicker RGM clutch plate arrived yesterday (the day after I ordered it: flippin' good service!) so once I've finished re-organising the garage (yet again, why do I keep all this crap?!!) I will fit the new plate and see how the clutch feels. If it is still heavy I'll replace the cable.

In the meantime, if anyone wants loads of old, used Commando spares and obscure special tools from unknown motorcycles just give me a shout! I recognised one as a clutch centre (or shock absorber) holding tool from a BSA Rocket III, a bike I haven't owned for more than 40 years, but all the other special pullers? No idea!

Re: Heavy clutch operation

Posted by colin_peterson at April 13. 2018
Previously Jem Nicholls wrote:

Hi Colin, you took me right back to my polymer engineering days (many years ago I was a plastics engineer) and PTFE is a highly crystalline polymer which, in our practical terms, means that nothing much can touch it and why it offers such low friction. So I think when Venhill say you don't NEED to oil it they mean just that. A thick oil would only cause drag on the metal cable inside the outer. It can't affect the PTFE, not much can apart from mechanical wear. But dirt and grit can sometimes work their way into a bowden cable so flushing it out with something light like WD40 or 3in1 would help in those circumstances. However, most of us keep the nipple at the handlbar end greased up so that should trap and stop most of the dirt getting in. Personally, I can tell that my clutch cable is in pretty good shape but the PTFE lining will wear away over time.

The thicker RGM clutch plate arrived yesterday (the day after I ordered it: flippin' good service!) so once I've finished re-organising the garage (yet again, why do I keep all this crap?!!) I will fit the new plate and see how the clutch feels. If it is still heavy I'll replace the cable.

In the meantime, if anyone wants loads of old, used Commando spares and obscure special tools from unknown motorcycles just give me a shout! I recognised one as a clutch centre (or shock absorber) holding tool from a BSA Rocket III, a bike I haven't owned for more than 40 years, but all the other special pullers? No idea!

Thanks Jem, good to know! I'm sure I'd heard tell of swollen lining being a problem in oiled, PTFE-lined cables, but from what you say presumably that was just mythology.

About old Commando spares, the only thing I'd like to get my hands on is a drive-side side cover for my MK2A, which seems to be quite a rare thing. Just on the off-chance. Cheers!

Re: Heavy clutch operation

Posted by ian_soady at April 13. 2018

I use GT85 in cables (lined and unlined). It is said to contain PTFE although probably only a tiny amount......

Re: Heavy clutch operation

Posted by john_holmes at April 13. 2018

There is an issue with nylon lined cables and oil, it also happens to roller garage doors with nylon sleeves, to lubricate both of these I use silicone spray and not had any issues. The one PTFE lined cable is on the Commando clutch and I use WD40 on this as per the Venhill instructions. Glacier PTFE bushes last twice as long with oil or grease compared to dry operation but these are bonded to steel which must limit the expansion.

Re: Heavy clutch operation

Posted by ann_nicholls at April 16. 2018

All sorted!

Certainly one of the cheapest yet best improvements I've made on the Commando. The 3mm plate was £12 total and the difference is impressive. I measured the force at the lever before (~26lbs) and after (~20lbs) and if you have aching hands that 25% reduction makes riding the bike a pleasure instead of a pain. I didn't do anything with the cable, that can wait, and a quick road test confirmed no clutch slip. Result! I'll now have a word with Ash at Andover Norton and see if they can be persuaded to carry the plate as an improvement (for those who need it).

Thanks for all your comments and help.

The next thing I'm going to try is a Dave Taylor head steady.

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