Clutch - what's going on here?

Jafa

So I tried to ride the bike up the driveway today for the first time, and the clutch felt terrible. Didn't feel a nice positive 'clunk as I put it into first gear either, couldn't feel anything.

Clutch plates measure

Pressure plate
Friction plate 1.97mm *
Steel plate 2.01mm
Friction plate 2.97mm
Steel plate 1.50mm
Friction plate 2.92mm
Steel plate 2.00mm
Friction plate 2.84mm
Steel plate 2.01mm
Friction plate 2.84mm
Steel plate 2.01mm
Friction plate 2.85mm
Steel plate 2.00mm
Friction plate 2.90mm
Steel plate 1.99mm
Friction plate 2.90mm
Steel plate 2.01mm **
Steel plate 2.03mm ***

* This is the plate on the outside, one side of it mates against the pressure plate

**According to the DesmoTimes book, this plate should be cupped like a Belleville washer, but isn't. It is dead flat and identical to all the other steel plates.

*** This plate has the same outer diameter as the others, but has a bigger inner diameter. The face is only about half as wide as the other steel plates.

All of those plates add up to a stack height of 39.75mm. Not quite right from what I've read? Shouldn't it be 38mm?

The very first friction plate ( against the pressure plate ) is down to 1.97mm. It is double sided like all the others should it be single sided ie no friction material on the face that sits against the pressure plate? Picture attached of this plate ( the totally worn one on the left ) with the second friction plate.

On the inside of the pressure plate, and the end of the clutch hub, are pitting marks from where it looks like the pressure plate has been hitting on the end of the hub, about 2/3 of the way around the bottom and up the left hand side. Pics attached. I take it these 2 shouldn't be touching? What would cause this too low a stack height?

There was also a copper washer under each clutch spring, but not all 6 were the same. 4 were 1.35mm thick, 1 at 1.53mm, and 1 at 1.86mm thick. All the springs are the same height though. Probably going to put it back without these washers unless someone can give me a good reason not to leave them out..

I need to get this back together enough to get the road safety inspection done, but that is all, about 150km of riding to get there and back. After that it'll go in the bin.

stafford

Looks like you need to drop the stack height back to the number you suggest, also in there should be a dished/convex plate that acts as a disc spring to stop the clutch judder on pulling away. This is normally the first single steel from the inside (or forth plate). You could get some 1.5mm steels but for a quick trip you should be able to drop the last friction as a temp fix and road test that. I can only guess that someone was trying to boost spring pressure with the washers, can't recall the service limit for springs though.
I'm sure others will have their own way, but it works for me.

patrick

Are you sure the 1,5 mm one is not a conical one? ( with a hole marked on one tooth)
at least one is necessary, two opposite works too, , with the second turned back from the pressure plate or the before last.
I agree 39,75 mm is too much , the clutch nut is 42 mm...
Avoid a friction plate near the pressure plate.
I 'd cancel thisone to reduce the total thickness to 37,75 mm, do a trial, perhaps it will slick.... the reason why there are copper washers rear the spring... and the added friction plate ... etc
At this stage it's time to buy a new set,, the best way to build a new stack of 38,5mm
if you cannot, you hav to play with parts you have (or from friends) but avoid more than 38-38,5 stack.
patrick

brad black

lh is a sintered plate. rh is a fibre style. it's all wrong. i'd get a complete new pack so you have a full set of nice steels and frictions. get an alloy plate pack - 19020111A.

Jafa

So I got a few replies from here and Duc.MS, so I went back to the shed today and had a play. First of all, I checked all the steel plates, and I found one with a small dot on one tooth, and sure enough it is conical. This plate was the second steel one from the pressure plate.

There was also another steel plate, but it is different to every other one, no teeth to drive it. The OD is a fraction bigger than the other stepelplates. Pic of it next to a standard steel plate

This different plate was the last one removed. It was sitting right back against the basket, past the hub. The ID is bigger than the hub so it went right over the hub and sat back past the back face of the hub. This plate is also conical.

So, I put in a standard flat steel toothed plate, then I put in this different conical plate, then the fibre and flat plates in the standard order. I put the toothed conical plate on the outside, next to the pressure plate. I left out the sintered plate completely. I also left out the copper washers from under the springs.

Wheeled the wreck out, fired it up, and what do you know, it feels better, isn't so grabby, and sounds right too. Rides ok up and down the driveway. So I'd say it's fixed enough for what I need.

I think they've put the extra sintered plate in to bring the stack up enough to get it to work because they had the odd conical plate back past the hub, so it wasn't actually doing much, if anything. Hence with only one conical plate, it might have been slipping which is why they put the copper washers under the springs. Bodge it up to fix your incorrect assembly. Nice.

Thanks to everyone here for their help and advice.

900SL

Well done Jafa....

Jafa

Brad Black said that the odd steel plate is a Barnet one. So I have a mostly stock fibre clutch pack, with 1 sintered friction plate and one Barnett Steel plate thrown in........

Going to see a bloke tomorrow to try to get another standard steel driven plate to replace the Barnett one.