[MarkO]

Hello there - thanks for your reply. Yes, it does, but not too bad. I had deemed it to be acceptable at the time but I suspect that the mainshaft may be bent. If I spin the input shaft with a verdict clock on the bore for the clutch pushrod, I am getting  approx 0.2mm runout at that point, which is some 50mm or so way from where the shaft is supported by a bearing.  At the edge of the clutch assembly, it is magnified to over 1mm, which as I said before, is close to the total separation distance that I get when I operate the clutch lever.

The 'wobble' does not help if I want to set up the clutch stops either. (although I have heard mixed reports about their benefits!)

It would be useful to have some pictures of the internals to perhaps get a better idea of exactly what is going on.

[singleminded]

does your primary chain tighten and loosed when the engine is turned over?..I think that you are getting neared to a bent mainshaft that you appear to suspect from your first post..I had a mainshaft that bent on my Vincent Comet and managed to get the use of a 50 ton Fly press to straighten it, not dead straight but usable.

[MarkO]

and another

[MarkO]

Sorry - another attachment

[MarkO]

Update. In the end I made a complete new clutch 1/2 pushrod to carry the needle roller bearing (see pics). It does seem to be an improvement in that the clutch outer plate now lifts more cleanly and seems less affected by imbalanced spring adjustment. However, the clutch runout/eccentricity is still an issue. I measured it yet again and it is well over a millimetre when measured at the outside of the clutch.
I think I need to get the gearbox out for a full inspection. It is the only part of the bike that has not been touched. It did seem to work reasonably well on test once on the move but selecting first from neutral and going back again was a nightmare that sort of got me to where I am now...

I just hope that I can get some improvement on the eccentricity problem. Am i expecting too much??

C'est la vie!

[phutton]

I had considered aneedle thrust-bearing, but never got round to it. I would be very interested to see how you do it, and how well it works.

The material that the Club supplies for the clutch stops is a friction material, similar to Ferodo clutch inserts, formulated to operate in oil.

[MarkO]

Thanks Paul and Singleminded for your Feedback. I measured everything again and its good and bad news. Clutch assembly run-out is not quite as bad as I thought but I re-meadured the amount of lift that I am getting and it is almost exactly 1mm, measured at the bridge. There is a second hole on the operating arm that is inboard of the first hole which obviously gives more lift but the force required at the handlebar lever is very high so I am reluctant to go down that route. I may look at better levers though. I checked that the basket bearing is free to float on the inner drive plate boss and it is fine. I actually tried a hardened steel wavy washer 30x36x2.7 (0.3mm thick spring steel) between the basket bearing and the inner drive plate - thinking that it might reduce any drag between the rearmost plate and the clutch basket. It seemed to work quite well in separating the two components (the basket can only move axially about 0.3mm with new corks) but did not significantly affect the overall drag. So, I took it out. I am now going for a phosphor -bronze button in the end of the mainshaft, possibly with an Imperial sized (0.31x0.790x0.078) needle roller thust bearing to push on the outer plate in the hope that it will lift more cleanly. Has anyone tried this? I also found that my outer plate, which at some time has been reinforced with an additional 2mm thick plate that has been riveted on, varied in thickness by almost 0.25mm. It was also not concentric with the centre. I have remachined it and it is now flat and true. So hopefully, all these little tweaks should help. Does anyone know the spec for the clutch stop material? I have carefully re-machined the face on the outer plate so feel more confident that the system might now work.
Thanks once again for all advice given. You will get to see this bike one day. I am determined to get it back on the road as Sunbeam intended!

[singleminded]

When you pull the lever back to the bars can the bridge lever be rotated anymore?.
If you are not using inverted levers then you can get levers with different cable/pivot distances.
On my Vincent Comet clutch I need the most distance I can get, about 1 1/8" pivot for maximum travel, on the brake I use 1" for maximun leverage.
The difference between 1" pivot and 1 1/8" pivot is about 0.4" pull on the cable.

[phutton]

Hi Mark,

Have you checked that the clutch basket bearing can float on the boss on the inner drive plate? If it doesn't then this can cause drag. Having said that, mine is OK but I still get drag!

On mine, a previous owner has drilled a second hole closer to the pivot in the operating arm on the bridge side. This increases the handlebar lever load, but does increase the lift by about 30%.

Another mod I have tried is to have a two-part pushrod with a 5/16 ball bearing in the middle. The end that engages with the outer plate is formed with a large diameter (about 1") mushroom head, and machined to be a good sliding fit in the mainshaft. It has made some improvement, but doesn't cure the problem totally.

Finally, adjustment of the clutch stops will help in selecting first at rest, but not much help for finding neutral!

Best of luck with it!

Paul

[MarkO]

Hello all

After a lengthy rebuild interrupted by other activities such as home decorating, gardening etc, I am struggling to set up the 6 spring clutch on my model 95L. I have new plain plates and a re-corked basket and two friction plates. Everything has been checked for flatness and the Clutch Cork Carvery has done a great job on the recorking. The springs are also new. The problem I have is getting rid of clutch drag. Pulling the clutch lever up to the bar, I am getting approx. 1.35mm of lift measured at the pressure plate. I have spent a great deal of time adjusting the springs to get an even lift on the pressure plate but when I operate the clutch a few times I seem to get varying amounts of drag. I understand that clutch stops can be carefully set up to help stop the clutch centre when in neutral but I would like to eliminate as much drag as possible before I refit the cover with all those little fillister screws!


One thing I have noticed is that the gearbox shaft is not running absolutely true. I placed a clock on the face of the outermost surface of the clutch centre and measured 0.35mm of run-out or 'wobble'. This translates to 0.75mm at the edge of the cluch basket.

With only 1.35mm of lift, 0.75mm of run-out in the whole clutch assembly when it is rotating on the gearbox shaft does not help in my quest to minimise clutch drag!

The only part of my bike that has not been dismantled and rebuilt is the gearbox. I was assured by the previous owner that it had 'been done'. However, he also said that about the engine - which took months of hard work to get right.

So my questions are:
Should I dive into the gearbox and try to get rid of the shaft run-out?
Am I expecting too much from an 84 year old machine and should I just put it back together and use it?

I should point out that I have already ridden the bike on the road and apart from the difficulty in engaging first from neutral and going back again, the bike performed faultlessly and seemed more than happy in 60-65mph traffic. It also handles very well. I have ridden many British singles but none felt as good as this. I can't wait to get  it back on the road but I do want to get the clutch as good as possible. It must have been OK when the bike left the factory!

Rgds

Mark Odlum