M33 6 spring clutch adjustment puzzle

[Rog1]

After stripping and cleaning my clutch of oil because it was slipping, then reassembling it, I found I had to slacken the clutch cable adjustment to get the little bit of free movement on the actuating arm. This was a bit of a mystery because I'd already slackened the cable when the clutch had started slipping, so I could kickstart the bike to get home.

The next day after reassembly I took the bike out. I did about one mile then the clutch started slipping again, really badly. I managed to get home where I found I had to slacken off the clutch cable again, by quite a bit. But the clutch still slips. What on earth is going on?

[Pete C]

are you adjusting the cable only? I would make sure that the adjustment inside the geabox cover, at the actuating arm, is correct first and the nut done up tightly. Then adjust the cable and see if the problem persists. BSA Service sheet 609 or 307 give details
A sightly bent or sticking pushrod can also produce strange behaviour.

[Rog1]

I'll have a look after the weekend, thanks.

[Rog1]

I finally got out to the shed and removed the pushrod. It slid out easily. There was a bit chipped off at the gearbox end so I filed the pushrod back. The pushrod was 1/8th" too long anyway, and is now a tiny bit under the standard length of 12 1/8th". I think I've managed to file it back far enough that the end is very nearly round.

It's all rehardened (I heated it up and left it to cool before I got the files out) and back in the bike. The ball in the adjuster is a bit marked, so I will order another adjuster, maybe a new pushrod too. The adjuster nut was not at all loose. We are supposed to be getting slightly warmer weather tomorrow so with a bit of luck I can test it on non icy roads. With a bit of luck, that was all that was wrong with it.

[Jim S]

Sounds to me like the clutch plates are not seating properly after you disengage then engage the clutch.  Is the outer plate lifting squarely when you disengage the clutch? Maybe there are burs on the plates or basket preventing the plates from seating squarely. Also check the primary chain in different orientations. A very tight chain may cause problems.

[Rog1]

Sounds to me like the clutch plates are not seating properly after you disengage then engage the clutch.  Is the outer plate lifting squarely when you disengage the clutch? Maybe there are burs on the plates or basket preventing the plates from seating squarely. Also check the primary chain in different orientations. A very tight chain may cause problems.

The clutch plates not seating properly is I think the problem; my road test saw the clutch still slipping. Time to strip the clutch again!

[Pete C]

"It's all rehardened (I heated it up and left it to cool before I got the files out)"
If you did that you have softened the rod not hardened it    If the soft end of the rod bells out you may have problems removing it from the gearbox tunnel.

this is the info from Ian Wright on the WD20 website

The pushrod you are buying should be made from 'silver steel' and have the ends hardened. Silver Steel is a flame hardening high carbon steel and it is easy to make alterations to a pushrod made of this material if required.

First you will need to soften one end.

Heat the end to red and allow it to cool naturally in the air. This will soften or 'normalise' it.

Once cold shorten the rod to the desired length..but take care. Small reductions in length make a lot of difference. When you are happy the rod is correct and the clutch adjustment is correct with the rod fitted, remove it and heat the end you have altered to red, quenching it immediately in cold water.

This will re harden the end.

Then clean the end off with some emery cloth until you have a bright finish.

You will now have to 'temper' the end. (this softens it slightly and makes it less brittle.)

Place the end into a fairly gentle flame and allow it to slowly heat up. You will see the steel gradually change colour as it heats, first to a very pale yellow, then a darker yellow...then brown. This is an indicator of the changing temperature of the steel.
Allow it to go pale yellow and just as it starts to darken quench it very quickly in cold water. The rod is then ready to use.

If you go too far and the rod goes brown simply heat it to red, quench it again, clean it off and have another go. Lubricate the rod well with some light oil before refitting...Your stainless rod was not a suitable choice...the material is far too soft

[Pete C]

If all the components are OK I use a dial test indicator on a magnetic stative to get the outer plate to lift squarely. It may be a bit OTT but at least I then know that is not the cause of any problems.

[Rog1]

Pete C,

Thanks for the advice, but what I meant was, I softened the rod, then re hardened it afterwards; I got it up to red heat then quenched it in oil.

To get the plate lifting squarely I use the depth gauge on my vernier calipers, measuring off the edge of the clutch basket; also maybe a bit OTT, but it's always worked well.

Roger

[Rog1]

Sounds to me like the clutch plates are not seating properly after you disengage then engage the clutch.  Is the outer plate lifting squarely when you disengage the clutch? Maybe there are burs on the plates or basket preventing the plates from seating squarely. Also check the primary chain in different orientations. A very tight chain may cause problems.

The lugs on the plain plates are rather worn, so I think that's the main problem; causing them not to seat properly.

But I may be wrong; as this is not the first time I've had issues with the clutch, yesterday I ordered a 4-spring clutch kit from Kidderminster Motorcycles. It arrives tomorrow.

[idie]

What often happens is that the friction inserts in the clutch drum wear at the back where you can't see unless the drum is removed. This gives a metal to metal contact which causes a problem. I have fitted a Triumph style clutch from Kidderminster to my M33. As it is a Triumph style you can get the same problem with sticking clutch plates which need freeing before trying to engage a gear. May be I am unlucky as I have a four spring on my Shooting Star with no problems.

[Pete C]

The Triumph clutch, as supplied by Kiddiminster MC, is a good alternative and I have these on an M21 and B31. BUT, as mentioned, you do need to free the clutch before starting the engine and if you leave it for any length of time it can get really stuck (the B31 clutch needed dismantelling after a few months of neglect. The whole stack of plates came out as one lump and needed prising apart).
In such circumstances tying back the clutch lever can help, but then some people may consider this detrimental to the springs.

[Grumps]

Just wondering. If when all freed up, is there a particular oil, grade of oil or mineral/semi etc that reduces the problem?

[idie]

I have tried engine oil, fork oil and ATF it happens with all. The only alternative would be running without oil and using grease on the chain,but then the clutch rollers would be a problem. I have read that using Surflex plates stops the problem. Have you seen the price!

[Grumps]

One spares guy I have spoken to said that Surflex sometimes we're the problem, sometimes warped.