Scrambler clutch basket?

[clanger9]

Is the clutch basket fitted to the 250 scrambler (or 350) model somehow deeper than the standard 250 one? The parts list shows "043198" for the 250 and "043173" for the CS & 350, so presumably there is a difference between the two.

The reason I ask is that my bike is fitted with the "extra" clutch plates of the scrambler, but the outermost plate is too close to the top of the basket. If I pull the clutch all the way in, this outer clutch plate sometimes spins around, jamming on the clutch basket and causing it to slip. To remedy, I can just quickly dip the clutch and it sorts itself out, but it is a bit annoying...



I suspect my bike needs a deeper clutch basket, but I don't fancy my chances of finding one...

[John Jarrett]

You are correct the 250 CS clutch basket is different to the road bike.

I have attached a picture of one if it helps.... the chainwheel on this clutch is simplex rather than duplex but a larger pitch than the standard lightweight simplex or duplex primary chain.

IMG_1293a.jpg

I believe that in 1962 the scrambler had a duplex clutch but I have never seen one.

I don't know the clutch configuration of a 350 lightweight but as you say from the parts list it used the same basket as the CS and as I understand it a duplex chainwheel. If you can get a basket from either, you may need to check whether the it can be matched to a duplex chainwheel without changing the clutch centre and/or the gearbox mainshaft which were also different on the CS and 350 lightweight.

Kind regards,
John

[Rangy65]

Hi Clanger there are differences between the clutches - 350 & Scrambler duplex with 9 plates and early 250's simplex with 7 plates. Later 250 CSR's also had the duplex clutch.

The other change is in the alloy pressure plate, 350 & Scrambler has less of a shoulder so not so tall.

If you have a workshop manual its on page 54 or 58 if you have the overhall manual from F Neill

Interestingly new clutch plates are thinner than the originals so i had to put an additional single sided plate in my clutch - please search on the G5 threads and you will find picures a plenty.

Your bike seems to have been heavily modified.

Cheers

Steve

[clanger9]

Excellent info, thank you both!

One thing I noticed is that my bike has a very thick plate at the base of the stack. It may be possible for me to replace it with something thinner. Also, if the new clutch plates are slightly thinner, then I could replace the whole stack as I only need it to be a millimetre or so thinner overall.

As far as I can tell my bike spent much of its life as some sort of track bike, so I have the added joy of trying to puzzle out how (and why) it's been modified.

I'll drop the plates out and have a bit of a think...

[Rob Harknett]

Have the plates been re corked with thicker corks? If so a little facing up of the corks on sand paper will soon gain 1 m.m. I assume they have not bent making them need more space.

[clanger9]

Another good idea, thank you Rob!

From memory, the plates were all in good condition with plenty of friction material, apart from one that had been 'cooked', so I replaced it. The plates are all flat, but I could probably 'lose' a bit of material - it's not as if I'm going to be racking up many miles on it. That'll probably bring the clutch plates into the basket enough to stop the outer one spinning...

[Rob Harknett]

Lets hope that simple job will cure the problem, its only .01 mm to remove from each cork plate surface. Also give them a clean up as well. Also check and remove any burs on the outer plate, it may had got due to spinning

[clive]

If you have old plates you may find a combination of new and old plates will give your clutch sufficient bite but reduce the depth of the whole plot. once it has worn a bit you can replace the old plates with the remain ing new ones. I have had to do this with heavyweight clutches especially with the replacement bonded on clutch plates. I would not continue to use it as it is at present because that spinning plate is eventually going to jam itself, or cause damage to the basket.

[Janet]

The reason I ask is that my bike is fitted with the "extra" clutch plates of the scrambler, but the outermost plate is too close to the top of the basket. If I pull the clutch all the way in, this outer clutch plate sometimes spins around, jamming on the clutch basket and causing it to slip.

I apologise for being blind/dim but are you saying that the final single-sided friction plate gets pushed out beyond the face of the centre and then spins independently or are you talking about it being pushed out of the case that all the plates sit in? Is the adjacent steel plate also going out too far with it? If the latter, that's what happened to my CSR and made a bit of a mess of the sticky-outy-bits on the steel plates which then spread the case.

The number of plates on my CSR when I got it appear to match the scrambler, which confused me because I thought it should be like the 350. Until recently I'd not had a problem with it, other than occasional adjustments so when I rebuild it again ( 'cos I broke it again ) I'll be putting back the clutch that worked for 7-8 years like that until it started playing up, but with new plates and then a complete refurbishment of the spare is the plan.

[clanger9]

Hi Janet,

Basically, the outer clutch plate moves above the basket when the clutch is pulled in. Hopefully this picture makes it clear:


The more I look at it, I think the basket is deep enough for 9 plates, but the problem seems to be with the extra-thick first plate. It's a bit hard to tell from the pictures in the manual, but this doesn't seem quite right.


I'm tempted to just turn the whole pack around and put the thick plate outermost instead of innermost. This looks like it should work. Maybe this is the right way?


I need to study the design of the clutch a bit more. Does anyone know for certain what the clutch pack is supposed to look like?