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Assistance sought with a Rapide Clutch problem please

BlackLightning998

Well Known and Active Website User
VOC Member
Evening All,

Well, at 5500 miles I am now to join the ranks of those who have "enjoyed" troubles with the standard Vincent Clutch - I have had faultless service todate however am now having problems.

I have posted this on Jtan too as some don't read both - would be most grateful for the benefit of experience from other members who have encountered this specific problem before.

Here's what I posted on Jtan:

Evening All,



So, here I go delving into the intricacies of the Vincent Clutch.



Mine is a standard set up which ran for 5500 miles pretty much faultlessly.



Then, after 230 miles or so on a very hot day, everything warm, the clutch slipped terribly, couldn't get mote that 30 miles an hour.



When cold, all perfect again - did 70 miles no problem.



Then on the next run did 45 miles at 70mph, then the clutch started to slip again.



With everything hot I checked the cable adjustment, all fine, the actuator arm, all fine with free play and just kissing the abutment on full lever pull.



So, I stripped the clutch and found a little (not a lot) of oil had found it's way into the clutch down the final drive shaft and also a dribble trail from the basket mounting screws. All cleaned up thoroughly and put back together again. The plate clutch outer and inner had "blued" in three locations as Richardson suggests happens but they look true enough on a piece of ground glass.



So - all back together and I was pleased with myself.



Out for a run, did 40 miles, no sign of slip. Then towards the end a different problem, on coming to a standstill at a junction, clutch pulled in, stalled the engine - the clutch was dragging slightly. However - it does not do this every time. At home I tried putting the bike on the stand and running the engine, clutch in, engage first and let out clutch - back wheel drives. Pull in clutch, back wheel stops. Do it several times and maybe once every 4 or 5 times the clutch fails to disengage fully and the wheel continues to turn, apply the back brake and the engine stalls.



So, I appear to have seen a problem (oil ingress) and cleaned and re-assembled the clutch only to cause myself another problem.



I'm confident that this will be something that Jtan'ners have come across before so I though best to post here and on the Forum to gain some assistance as to what to look for, what to do next?



I was meticulous with the strip and re-assemble and am pretty confident that all went back just as it should - however something is obviously array so would appreciate guidance.



Many thanks.



Stuart Metcalfe
 
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BlackLightning998

Well Known and Active Website User
VOC Member
I'm a pratt!

Hi Everyone,

So, I'll own up to what some of you may have suspected for some time - I'm a pratt.

Having thoroughly read Sib Biberman's "how to set up the clutch", FYO, ATY, Richardson. KTB and the Riders Manual plus spoken to my Vincent Engineering Mentor and a few other friends, I thought I had nailed down the possible problems with my clutch.

Interestingly, when you used the clutch to depress the kickstart, the first time it might slice through like a hot knife in butter. If you then used the valve lifter to turn over the engine and try the clutch lever again you'd find it locked solid. Ahh - I hear you say, the famous problem of springs not allowing the plates to lift square. The problem was a little deeper than that.

I stripped the primary out and found that the shoe carrier was binding, no end float. I had meticulously taken it apart, thoroughly cleaned it and re-assembled exactly as it had come apart, but I'd clearly got the clutch nut a little tighter than it had been and in so doing had removed any end float in the shoe carrier which was subsequently binding - and it got worse on a hot engine of course.

My bike had two thrust washers (PD19) - one thicker than the other. So I've removed the thinner one, cleaned everything again and put the nut on properly tightened and locked with the lock spring.

I then polished all the spacers for the 9 steel pins (might not do anything but I read about it in FYO and it made me feel better - so worth doing!) and made sure that the springs, cups and spacers were all mated nicely as sets with the springs measured. Then re-built the primary, adjusted the spring locations to try and achieve an even lift and tried it out, however many times I span it over on the kickstart and valve lifter, the clutch lever then always freed off the kickstart to slice down nicely - success?

So I put the cover back on and took it for 40 miles, not enough yet to claim full success I know, but enough to think I may well have got it sorted - a lovely sweet clutch and hugely enjoyable 40 mile test ride - hurrah!

Oh, and an interesting non-sales tip - in my Sunday night frustration having had a tough ride home from the White Horse Rally I emailed Russ Kemp at VinParts (other parts suppliers are available) and ordered a load of new Primary Clutch parts as I suspected my "blued" ones may be the problem. Russ spoke to me on Monday and encouraged me to persevere to try and get it sorted before buying new bits - good bloke.

So, given my very amateur status on the Vincent Mechanic/Engineering front I am pretty chuffed that I seem to have sorted my clutch clip, caused a clutch drag and sorted a clutch drag all in the space of a few days - and in the process stripped the clutch and re-built it twice.

If ever there was an example to follow this must be it, if you've been thinking of whether or not you can have a go yourself and get the satisfaction of maintaining your own bike - have a go.

I hope I'm not premature, I know it's only 40 miles and I need a good 200 and a stonking hot engine to prove the repair - but I do hope that I've found it and frankly, I don't feel a pratt, I actually feel quite chuffed.

Thanks to all who helped out along the way.

Bucks Shiny Bike Night tomorrow night - and I'm going on the Vincent......

Regards
 
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CollingsBob

Well Known and Active Website User
VOC Member
My clutch is both dragging slightly..and slipping under hard acceleration...I have printed out your post and will use it as a reference for my trouble shooting...
 

BlackLightning998

Well Known and Active Website User
VOC Member
Also have a look for the thread on "Stop Quick"

My clutch is both dragging slightly..and slipping under hard acceleration...I have printed out your post and will use it as a reference for my trouble shooting...

Hi Bob,

Fingers crossed it can help you. Worth reading the books and manuals I reference, I think the only thing that these did not mention was the importance of end float on the shoe carrier that I learnt from Sid Biberman's post on Jtan - if you are not a Jtanner let me know and I'll send you the emails direct with Sid's clutch building tips.

Finally - have a search for my thread relating to "Stop Quick" a napther based product for cleaning clutch and brake parts - hugely recommended to put some into a metal tray and use it as a bath for thoroughly cleaning all your components as you strip them out - makes a lovely job and reassembly a pleasure, all these sparkly clean bits. It evaporates to nothing as well - so does not need any cloth drying.

Best of luck - keep the Forum posted on how you get on....

Regards
 

Tim Kirker

Active Website User
VOC Member
Vincent Twin Clutch

There's a longer version of this under the V3 Clutch Thread started by Tom Gaynor - round about Page 4.

The actions taken thus far are fine but there are a couple of comments I would add in case you haven't quite got to the bottom of it.

Getting the primary to lift square is not just down to the spring pressures. Check that the ends of the push rod and the adjuster in the outer plate are dead square. I was amazed what a powerful affect this has if one of them is slightly out.

Clutch slip and/or clutch drag can be caused by the spring plungers in the clutch shoes being set wrongly - one pulls the shoes off from driving, the other pulls them off from the over-run. If the spring pressure is too low the clutch tends to stick on and drag, if too too high the main clutch may not engage properly and the clutch slips.

Another factor possibly contributing to clutch drag, which I have addressed, is that the two plungers should "balance" the clutch at rest. In my case they were out of balance so that the over-run shoes were virtually rubbing the drum, and the drive shoes were 2 or 3 mm clear. I corrected this by adjusting spacers around the respective pins.

With reference to end float of the shoe carrier, don't over-do it. If there's any wear in the bushes of the carrier (which is almost certain) the carrier can rock side to side, which is limited if the end float is limited.

Finally a tip. When carrying out your test of depressing the kick start lever with the clutch disengaged, to see if it drags, it's easier to do, and easier to see what's going on, if you put it in 4th gear and turn the back wheel. (Unless you've got an assistant to operate the kick start.) This has the added advantage that you can simulate both directions. Turning the wheel forwards makes the clutch operate as in the over-run and turning it backwards makes the clutch operate in drive mode.

But, if it's working OK, and it ain't broke, for God's sake don't fix it!
 

BlackLightning998

Well Known and Active Website User
VOC Member
Thanks Tim, a few questions for guidance if I may?

There's a longer version of this under the V3 Clutch Thread started by Tom Gaynor - round about Page 4.

The actions taken thus far are fine but there are a couple of comments I would add in case you haven't quite got to the bottom of it.

Hi Tim,

Very helpful thanks - I have a bit more research and reading to do on the subject as I think I am now into the realms of seeking to "fine tune" my clutch - it works fine but I think I'd like it to be just that little bit better than I have it to assist smooth gearchanges.

Any chance of some guidance on the following:

1 - "Getting the primary to lift square is not just down to the spring pressures. Check that the ends of the push rod and the adjuster in the outer plate are dead square. "
Two questions:

1.1 How do I check it?
I haven't a lathe to put the outer plate (with adjuster) in it and spin it up - so how can I go about finding out if mine is square (have read the notes on V3 so know about the issue)?

1.2 What does a "good" pushrod end look like?
Can anyone post a photo of what a proper pushrod end (clutch side) should look like - mine "looks" OK to my untrained eye and looks like it has a bright spot right dead centre where it is touching the ball bearing in the end of the adjuster, but I know that the primary has got really hot (3 blued spots) so if there a chance that the pushrod end has lost its hardness and trouble awaits me? It would be really useful to know what a good one should look like so that I can compare it to mine and keep an eye on it.

Here's a picture of mine below.

2 -"Clutch slip and/or clutch drag can be caused by the spring plungers in the clutch shoes being set wrongly - one pulls the shoes off from driving, the other pulls them off from the over-run. If the spring pressure is too low the clutch tends to stick on and drag, if too too high the main clutch may not engage properly and the clutch slips."

I'm fairly convinced I now have it engaging properly - it pulls like a train uphill to three figure speeds with no sign of slip whatsoever.


3 - "With reference to end float of the shoe carrier, don't over-do it. If there's any wear in the bushes of the carrier (which is almost certain) the carrier can rock side to side, which is limited if the end float is limited."

I think I am sorted thanks - I will get around to measuring the thickness of the thrust washer I removed (there were 2 and I took out the thinnest) so that should give me a sense of the end float I have created. I understand that the carrier bearing is an important factor on getting the lilft square and reliable - I'll keep an eye on that thanks.


4 - "Finally a tip. When carrying out your test of depressing the kick start lever with the clutch disengaged, to see if it drags, it's easier to do, and easier to see what's going on, if you put it in 4th gear and turn the back wheel. (Unless you've got an assistant to operate the kick start.) This has the added advantage that you can simulate both directions. Turning the wheel forwards makes the clutch operate as in the over-run and turning it backwards makes the clutch operate in drive mode."

Easier said than done with a Grosset Electric Start (one direction only) - however that is easy to drop out with three allen screws. One of the benefits of being tall is long arms which help out on the job, but getting a friend in is a good call - I think that's next for a little bit of fettling!


5 - "But, if it's working OK, and it ain't broke, for God's sake don't fix it"

Having been through the emotional roller coaster of having caused it to stop slipping and then dragging all on my own, I feel a little more comfortable about going in again to try and fettle it to a step closer to perfection. My Vincent engineering mentor advises me that one of the most important steps to a smooth gearchange is having a clutch which disengages properly - I use "properly" rather than quickly as of course I have read that the Vincent clutch isn't always an instantaneous disengage.

However, replies on the above questions from you and/or other more experienced members than myself will help me prepare myself and think through what I might and might not attempt.

Is the mini-valve the answer - if so, I've missed it in FYO etc, where can I find out about how to do that mod?

Regards
 

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Tim Kirker

Active Website User
VOC Member
Stuart

A hasty response 'cos it's section night tonight.

I may have caused some confusion because there are two types of adjustor fitted in the outer primary plate. Some (I believe earlier type) are ball ended and some (I think later type) have a flat end like the push rod. Mine is flat ended and it sounds like yours is ball ended. I think the idea was that the flat end would tend to lift squarer, even if the pushrod was not dead central to the adjuster. (Looking at your photo, it looks as though the contact point may be slightly off centre on the pushrod.) Another advantage of the flat end is that the load is spread and the tendency for the ball to bore a hole in the pushrod end is removed. In either case it's important the pushrod end is square. A fairly simple test would be to remove the pushrod and see if you can easily stand it on its end, on a flat surface. It won't need to be far off square before it won't stand up. Or, put it in a drill and rotate slowly - can you see the end "wobbling"?

Assuming it's square, the picture doesn't show much wrong with your pushrod. The end is flat, no significant wear. (The two ends of the rod should have been hardened to limit wear. This is usually evidenced by a bluing discoloration over about half an inch at each end.)
 

timetraveller

Well Known and Active Website User
VOC Member
I agree with Tim about the push rod but what is that terrible scar on the back of the clutch drum? Is that recent or evidence of a previous life? With regards to the Mini exhaust valve; I went for this option several years ago having heard of it but not having seen it in writing. One of my neighbours has a daughter who at the time had several Minis and lots of bits including a scrap head complete with valves. My memory is that the valve stem was the correct diameter but I had to turn the back of the head down so the at the shape was more like a penny on a stick. It was necessary to remove the adjuster in the middle of the clutch outer plate so that the valve head now pushes against the outer periphery of the large nut in the middle of the clutch outer plate. I sprayed both that nut and the head of the valve with non fling chain grease and let it set for a couple of days before using the clutch. The clutch outer plate now has to lift more or less square. The only down side is that there is now no adjustment in the middle of the clutch and all adjustment has to take place on the cable and on the adjuster in the kick start cover.

If I was to design this to make a batch for others to use I would make a new large nut for the centre of the outer plate to take a thrust washer with rollers and a hole through the centre. I would not use an old valve but rather would make something with a similar shape but with a continuation of the 'valve stem' to stick out through the 'valve head' and to pass through a hole in the middle of the new nut. This would act as a locater for the outer plate. If there is enough interest in such a device then it would not be a lot of effort to design it and get some made. Over to you chaps.
 

BlackLightning998

Well Known and Active Website User
VOC Member
Thanks Tim - no rush for a reply to this one...

Stuart

A hasty response 'cos it's section night tonight.

I may have caused some confusion because there are two types of adjustor fitted in the outer primary plate. Some (I believe earlier type) are ball ended and some (I think later type) have a flat end like the push rod. Mine is flat ended and it sounds like yours is ball ended. I think the idea was that the flat end would tend to lift squarer, even if the pushrod was not dead central to the adjuster. (Looking at your photo, it looks as though the contact point may be slightly off centre on the pushrod.) Another advantage of the flat end is that the load is spread and the tendency for the ball to bore a hole in the pushrod end is removed. In either case it's important the pushrod end is square. A fairly simple test would be to remove the pushrod and see if you can easily stand it on its end, on a flat surface. It won't need to be far off square before it won't stand up. Or, put it in a drill and rotate slowly - can you see the end "wobbling"?



Hi Tim, thanks for that. I guess that as the bright spot on the pushrod is fairly central that would suggest that I don't have a potential problem with the central adjuster nut assembly as described in the V3 posting page 4 - it was this description of the adjuster nut being 4mm off square that I was wondering how to check without the means of mounting in a lathe. What I didn't think through properly was that the piece that worked against it, the pushrod, would show up any off square operation, with either a bright spot off centre or more than likely an over diameter bright spot given the rotation of the adjuster nut (on its clutch plate) and the pushrod relative to each other - each operation of the clutch would then force the pushrod onto a fresh section of its head to the ball bearing and hence a larger bright spot.

Is my logic right?

Cheers
 

BlackLightning998

Well Known and Active Website User
VOC Member
Twas not me......

I agree with Tim about the push rod but what is that terrible scar on the back of the clutch drum? .

Hi Norman,

The scarring was just one of a number of mechanical maladies that we discovered when the bike was stripped to repair the damage caused by the cams and followers, a broken valve lifter linkage, the followers not eased and showing bright spots, loose everything under the kickstart cover, loose gearbox camplate locator not lockwired, broken ESA springs (4000 miles) and the list goes on. All this following a pretty expensive re-build.

I was pleased to see that the scarring was dull and covered with dust when I stripped the clutch this time (last time bright and fresh) so I suspect that this specific problem has been resolved. Additionally the assembly did not have the spacer washers (I think you use the ones from the timing side) over the pins - it does now.

If I was to design this to make a batch for others to use I would make a new large nut for the centre of the outer plate to take a thrust washer with rollers and a hole through the centre. If there is enough interest in such a device then it would not be a lot of effort to design it and get some made. Over to you chaps.

What do I need to do next to spur on this potential modification process - I'd be happy to be the test bed as I can now easily see and understand the value of a parallel/square lift? Using my maths colleague at work to calculate the number of permutations for the 6 sets of springs and cups on the nine pins, then the additional possibility of putting small washers in the base of the cup to increase spring tension seems like a lot of work to get the same end result as the idea of the mini valve.

Isn't there also a possible modification of a larger centre to the clutch adjustor, incorporating a much larger ball bearing and a very much oversized head on the pushrod, so that the need for the non-fling chain lube is done away with by continuing to use the rotating nature of the ball bearing surface?

Additionally - what are your thoughts on my observations in reply to Tim about the calculation of "square" for my nut and adjustor mechanism mounted on the outer steel plate?

Regards and thanks once again for your help.
 

timetraveller

Well Known and Active Website User
VOC Member
Hi Stuart. I do not think that you have a problem with the end of the push rod or the adjuster nut. True, the dimple in the end of the push rod does look to be slightly off centre but my guess is that this is not a problem. To check for squareness on the end of the push rod you could probably use a decent set square and a magnifying glass. The idea for a 'penny on a stick' actuator would need a new large nut. You might not be aware that there are things called thrust bearings which consist of a radial cage in which there are rollers. These are designed specifically to take a thrust perpendicular to the plane of the bearing, i.e. to act exactly as we need. I would have to look through a catalogue but one about 30 mm diameter would probably be about right. The new large nut would be designed to take this bearing and the new 'pusher' would have to be hardened. I would need to talk to a metal treatment expert but my first guess is that it would be better to make up the pusher as a thick washer and then weld it onto a 1/4" diameter piece of rod. This piece of rod would protrude through the washer so that it could locate the outer plate when assembling. Given sufficient length of shaft inside the main shaft the outer plate just has to lift square. Because we are talking roller bearings here there would not be a need for chain type grease.

If you are serious I will work out a price but a one off is going to be more expensive than doing a few.
 

ET43

Guest
Clutch seperator mod

When I used a standard clutch, I refined the mechanism by removing the large nut in the outer plate, turned it around and screwed it in backwards, dispensing with the adjuster. This then presents a circular recess for a turned down Mini car exhaust valve to fit in to. Between the valve and plate was a solid dry running thrust. The adjuster in the plate was dispensed with and a roller from a bearing put between the now shortened push rod and the valve. This was a 90% success. Finaly I evolved a stepped slotted collar to fit over the G94 inside the cover and fitted a tapered light spring between it and the G91 arm. One had to set up the clearance of the push rod first, so that when turning over the engine with the clutch in, there was no drag, and sufficient clearance at the handlebar, then insert the spring. I firmly believe that a lot of clutch problems, especially slipping, is caused by the non return of the cable to it's normal position by way of friction in the cable. After all, it is only returned by the action of the clutch springs, so my little spring returns it to where it should be. However, you will not have any free play at the lever when and if you do this.
Cheers,
Phil ET43 Primmer Ace Bodger.
 

Hugo Myatt

Well Known and Active Website User
VOC Member
Just to add to the fun when I fitted my NOS outer clutch plate it tilted on lift. Having checked it very carefully I have discovered that the thread in the plate for the thrust plug C26 was not tapped square. I have tried two different C26s with the same result so it is the plate not the plug that is at fault. (Thanks John for pointing me in the right direction).
 

donrapide

Website User
Non-VOC Member
Just to give some idea as to how to fit a radial needle roller bearing and the attachment on the end of the push rod.

It is of course a Burman clutch but the idea is there. I found this a vast improvement of the standard layout. It still means that you have to make some attempt to balance the springs, but does make the clutch less likely to drag.
 

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timetraveller

Well Known and Active Website User
VOC Member
Thanks Donrapide. I spent some time yesterday evening Googling around and finding what might be suitable needle roller thrust bearings and found that they come with two types of outer washer. I note that yours is held in place with a circlip. Does that mean that it came as a one piece assembly or did you put the three parts in there and then hold them in place with the circlip? I had got as far as designing something that looks rather like your 'penny on a stick' push rod, even to realising that a double diameter would be the way to go but I was assuming that the push rod would take one of the hardened washers as a push and Loctite fit. Is your push rod hardened or do you rely on the hard washer which is part of the thrust bearing? Once again, thanks for the input. :)
 

donrapide

Website User
Non-VOC Member
With ref to Timetraveller's query, the needle roller came in three parts.

The circlip, made from stainless steel wire, is just to prevent the bearing falling out when assembling or walking inwards when there is no pressure on it.

There is clearance between the circlip and the rotating outer bearing track so that when clutch is lifted the outer track is free to rotate.

The attachment on the pushrod is made that way so that the coned part ensures entry when assembling. The second bit is to centralise the push rod into the bearing and the flange bit is to bear onto the outer bearing track. The flange bit is not hardened, made from stainless, originally put together with Loctite Retainer, which did not last long. So now is silver soldered on. There is no sign of any wear on either the outer bearing track or the attachment.

The main reason for fitting this was to try and get even and level lift, thus hopefully giving no drag.

The next trial, maybe next winter, is to fit a clutch brake to give soundless 1st gear engagement and a sweeter gear change. There is always something to play with these machines!

Hope explanation is fairly clear, if not, get in touch.
 

timetraveller

Well Known and Active Website User
VOC Member
I'm not averse to a bit of peril. Is a Norton clutch mushroom of the type you refer to like a penny on a stick, about 1.5" long and with a head about 0.75 to 1" diameter? If so I have one of those in my sprinter engine from 40+ years ago but I am hoping for something a little more sophisticated if we are to use a needle roller thrust washer. I have a needle roller thrust bearing arriving today so once I have my hands on it I can consider the design of the rest of the bits. :)
 

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