AMC Clutch - M31. What the ........????

[Greybeard]

Now that I've finished sorting out Mrs GB's Morini 3 1/2 I thought I'd check over the clutch on the M31DL. Apart from adjusting the pushrod I'd no cause to delve further since getting the bike. It was sweet enough and gear selection was always silent but it did sometimes drag a bit when hot. Not a continuous drag, more a pulsating drag but irregular, if you get what I mean.
When I took the primary case off, everything looked OK and clean. It was when I took the pressure plate off that my jaw dropped Inside the plate was a ring of thick black paste.

clutch.jpg

Taking off the cover for the cush-drive centre I found the source. There were no rubbers at all left in the centre

cush.jpg

I've never come across this before and it struck me that a previous 'restorer', rather than replacing the drive blocks, had filled the gaps with silicone. Whilst the paste smelled of rubber when I slung it on the workshop stove, there was no sign of any particles that looked like rubber, just a thick paste that had adhesive qualities far outperforming that of anything that would stick to an Army blanket!
Has anyone else experienced this sort of thing with original rubbers?

Needless to say, new rubbers will be ordered along with new springs and a set of rollers whilst I'm at it. The clutch plates, apart from being greasy, have plenty of meat on them and should clean up OK. Unless they decide to show signs of slipping/dragging when I get them back in, I'll hold off on a new set for the time being. It's only an easy afternoon's job to replace them if needed.

Another thing I noticed was that the clutch basket itself appears to have been copper plated - the identical one on my G80 of the same year is just plain metal. Surely it can't have been restored by some Lambretta owner can it? Or perhaps it's an AJS De Luxe thing

Steve

[ajscomboman]

Copperised back plate is not unusual, seen a few. As for the black gunge, that too is something that is common. It must be a combination of factors, type of rubber used and whether the oil used in the primary has detergent etc in it. I always have black rubber residue when I have had cause to delve in my chaincases. I don't think that it would have been filled with black silicone as that doesn't tend to go sticky at all, quite the reverse in fact. I'd say that the clutch has been together quite some time for the rubber gunge to get that bad, so it's not surprising that there isn't much left inside the centre. A good cleanup and new rubbers and I'm sure it'll be good again.

[Greybeard]

Thanks for that. I must have been damn lucky over the past 45 odd years it's definitely a first for me and I've stripped a few bikes over that time. I tend to use ATF in the primary case, only because I have nearly a gallon of the stuff to use up from years ago - otherwise it'll be a splash of straight 30.

Cheers. Steve

[ajscomboman]

Probably just something to do with the rubber compound. Your's is the worst I've seen but it certainly isn't that unusual. When I've opened up the centres I've found gloop and sloppy rubber balls but yet to find absolutely nothing. I also used ATF (had a gallon but now gone) so more recently just started with SAE 30.

[Mick D]

Hi

My money's on the rubber being incompatible with ATF - ATF causing the rubber to soften and swell, the clutch spider then munching it up to a paste.

Maybe someone should soak a rubber, (as currently supplied), in a jar of ATF and report the results.

Regards Mick

[Greybeard]

I think it's unlikely to be the ATF, Mick - I've only been running the bike for a year or so and I doubt if it would have had time to do that much damage. Who knows what it's had in there before
My money is on dodgy rubber blocks rather than the oil per se. I understand that the bike was restored at least 20-25 years ago though I've no idea whether they were replaced then. The restoration was done very thoroughly from what I can tell, and to an excellent standard, so they could have been iffy pattern parts I suppose. Certainly there were two sets of punch marks on the cush-drive cover screws, so they must have at least been uncovered once in the last 60 years.
The friction plates have cleaned up fine, along with everything else, though my manicure is ruined. At least it looks like being a cheap fix after all that - which we like

Steve (wot needs a big tub of O'Keefe's Working Hands now)

[Duncan]

Regarding the clutch rubber breaking down, as Rob and Tom Jones both say, its not unusual.

[ajscomboman]

Regarding the clutch rubber breaking down, as Rob and Tom Jones both say, its not unusual.

So what's new pussycat? I'm not usually wrong. If only that was true!

[Greybeard]

Regarding the clutch rubber breaking down, as Rob and Tom Jones both say, its not unusual.

So what's new pussycat? I'm not usually wrong. If only that was true!

I thought I was wrong once, but it turned out I wasn't - so I think I was wrong that time, wasn't I?

I've just ordered all the bits I need form AMOC Spares - in fact I've taken the precaution of ordering 2 sets of bits and I'll replace the ones in the G80 which is the same age and I restored that one nearly 30 years ago now - it definitely still has the original rubbers in that one. Well, they should still be in that one. I'll find out when I take it apart

Steve

[bigwol]

Rubber will eventually return to its "natural" state or a thick sticky gunge. I had them same with a belt drive turn table I got working after many years of non use. An hour of cleaning with surgical spirit and a new drive belt later and all was well, as i'm sure your clutch will be.