Hi All, I'm awaiting delivery of a new set of clutch friction plates but can't remember the critical thickness of the combined friction/slip rings. Please can someone remind me how thick the whole lot needs to be? My bike is a 2003 999S with 8 friction plates. Many thanks Steve
this will get the old thread stirring spoon going again! ^ not taking sides but Brian is right officially I think but the truth is it's not that critical and I know i've used 36 or less before if the slave and master are up for it. The thread search will reveal plenty including one recommending you not to go by stack-height at all. I think 38 is possibly the max without danger of last disc popping off the drum but again, it varies if non-manufacturer's kit or slipper clutches are used.
I've fitted new friction plates today - Newfren ones from eBay. I've got a question though....... The old clutch pack had 8 friction plates, so I bought a replacement pack of 8. Due to the extra thickness of the new plates I was unable to make the combined friction/steels add up to anything like 38mm. The steel plates are all 2mm apart from two of them, which are 1.5mm. The only way I could achieve 38mm was to take out one of the friction plates, so it's now only got 7. I've tested it, and it seems to be working perfectly. Do I need to obtain a set of 1.5mm steels, so I can include all friction plates, or do you think it will be ok with only 7?
Can I recommend putting a friction plate in first? This will sit lower, as the friction plate slots have a curved profile at the bottom. Because the tangs sit down inside the curve of the slots, they will dampen the movement of the whole stack, quietening the clutch and preventing it from rattling and banging backwards and forwards, so the plates will last much longer as well. Try it - works a treat...
The 1.5mm steel plates will be convex plates - look for a dot on the surface - they should be at specific points in the stack - useful summary here - they state 38mm +/-2mm. I also think (not 100% memory) that 36.5mm is for slipper clutches.
I'm sure the guy who wrote the Avanti article knows enormously more about these bikes than I do but I'm quite sure he's wrong about why the quiet clutch mod works. I've spent many hours trawling the forums on this subject and I'm quite convinced that it is because the plain plate tangs sit in a square bottomed slot and the friction plates sit in a slot which is curved at the bottom. As the bottom plate is normally a plain plate, that means that all of the plates sit in a parallel sided slot and are free to clatter backwards and forwards within those slots. However, once you put a friction plate in first, it then sits down inside the curved section at the bottom of its slots where it is no longer free to rattle about. Because it is sitting lower down within the slot, this usually means that you need an extra plate to make up the effective stack height to where it was before in relation to the top of the basket. Some people find it takes one plate, others two. A friend of mine didn't add any and reckons his clutch still works perfectly. Having the bottom plate jammed down into the curve at the bottom of the slots dampens the whole stack, meaning that it now no longer bangs backwards and forwards, destroying itself and the basket. Incidentally, I believe that the pressure plate is supposed to be installed in one particular orientation, with the triangular arrow on the plate next to the post with a slot in it, if I remember rightly. I don't know why though, maybe it's a balance thing... Ps Top tip. If you have steel plates, best way to get them out is with a small magnet on a telescopic stalk, or preferably two. Works a treat! Think I got mine in Tescos. Don't buy the type with an LED built in though, they're too bulky.
I did this mod with my 749 and it defiantly works. A lot less clattering now in neutral but still the lovely 'tinging' sound when clutch is ingaged. I replaced one of the two last steel plates with a worn friction plate. Simple 10 minute job and there's loads of you tube videos to look at if your not sure and I would recommend this mod to anyone. Tip I was giving was simply don't mix steel fiction plates with alloy friction plates as the steel plates will mash up your alloy basket. (obviously)
