Assistance sought with a Rapide Clutch problem please

BlackLightning998

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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

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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

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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

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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

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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

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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

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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

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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.
 

roy the mechanic

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clutch

Goto your freindly local Norton specialist, ask for a clutch"mushroom" this is the best thing for a square lifting clutch, ignore this at your peril! Roy.
 

timetraveller

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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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