...so the quest for the perfect stack height continues. ATM I've got aftermarket alloy basket with a set of 7 alloy friction plates and an STM hub. When the clutch was running with the OEM steel basket, it used 7 x friction plates (F), 7x 2mm steel plates (S) with a dished 8th 1.5mm plate (D) on top like this... hub-F-S-F-S-F-S-F-S-F-S-F-S-F-S-D-pressure plate. If I use that combo in the new basket, it drags. By losing the dished plate, the pack measures 35.4mm but the clutch slips very slightly and occasionally chatters on pulling away. All the STM instruction sheets I have managed to find seem to be very insistent that the stack height should be in the range 36 - 36.5mm and this concurs with my findings. So I'm thinking that if I ditch one of the 2mm plates, and replace it with 2 x 1.5mm plates, I will increase the stack height by 1mm and bring it back into spec, getting rid of the chatter and slip. Now, my question is: Is it possible to use 2 x 1.5mm dished plates together? I propose to build the stack like this...('cos I've not got any 1.5mm flat plates)... hub-F-S-F-S-F-S-F-S-F-S-F-S-F-DD-pressure plate I have also read that the two spring plates should be arranged like this: () & not like this: )(. Does this sound feasible? Or should I try and get a couple of 1.5mm flat steel plates? Your comments and obvs very welcome, as usual. Cheers S23.
Not familiar with STM hub but IIRC Ducati suggest 38.5mm? However at 38.5mm I always get drag and can't get neutral at stop so I have reduced mine to 36/37ish. Never a popular suggestion when I've mentioned it before but I don't see the need/point of dished plates and so don't use them at all and I have 2 perfectly operating Ducati dry clutches. To get the correct stack thickness you will find it easier if you can source some 1.5mm flat plates. They are available as they were made for use in (I believe) racing applications where more friction plates are fitted and so thinner steels are required.
Fitting 2 dished plates is one of the ‘fixes’ for chatter. I would however use them either side of a friction plate in the middle of the stack, rarher than under the pressure plate. 36.5mm is the ‘target’ dimension. Andy
After a while you'll forget the 36.5mm and opt for feel. Once I did life was easier. Can I ask, does your hub have removable posts? The posts where the spring caps screw onto? If so, check they are seated properly and loctite the bastards down. Otherwise your clutch cover may become inscribed with a nice circle and your clutch full off swarf. Dont ask me how I know this. One of mine was proud when bought new and needed screwing down, this one kept coming loose. Also are you re-using your old springs? If it came with new springs, then great. I bought some springs on fleabay once, never again. They lost their springyness after a short while and again led me on a wild goose hunt. Replaced them, wow everythings back to normal again. I agree with Android, the dished ones are just to 'pack out' to lose some of the chatter. JHP sell 1.5mm and 2mm plain plates on next day delivery. Buy a few of each. @Nelson on here advised me about a lithium grease thing, which to this day I wonder if he was pulling my leg. I baked the fuckers and smoked out my house like it was on fire. It helped for a while, but my graunch returned. Which was due to me using oem cover and not a vented cover. The graunch would disaappear whenever i used vented. Its the dust and shit. Gets trapped between plates. But I prefer oem cover. It protects the clutch on an off. Also make sure push rod is correct and seats in the bearing holder of clutch end plate. Check the bearing is seated properly too. I also make sure my clutch is bled 100% and no leaks from master cylinder BEFORE i do my clutch. Not doing that again. But generally I just bung them in so it works ok in garage. Then test it on road. If it slips, I swap a 1.5 for a 2. If I have difficulty changing gear, I swap a 2 for a 1.5 and so on. I put the dished on either ends of the pack. This works for me. Trial and error. You'll be amazed just how quickly you can swap a clutch pack about after a while.
stm evo slipper drum with 12 tooth basket? stm clutches are very fussy with stack height. 35.5-36.5mm is right if you are using the 48 tooth basket and plates but I think for the OEM basket its a little larger, possibly 38.5mm but i'm not certain. have you asked STM or WRS or a UK STM supplier to see what stack height they recommend when installing the EVO 90mm drum with oem basket and plates also the spring plates were put there by ducati to tune the feel of the clutch with the OEM drum. STM don't supply or spec dished plates afaik, you might want to consider ditching the dished plates altogether to see how you get on and only add them in if you find you have issues with low speed clutch control.
Hi Bootsam, my hub is the STM postless slipper design with the spider spring for the ramps and the circular primary spring to load the pack. Now are there any strong views on running two steel plates next to each other? Just been warned off doing this (and I must admit the warner knows what he's talking about - no disrespect implied!) but I'm sure I've read about it elsewhere. Views?
On slipper clutches, no idea but on standard clutches OK although, IMHO if there's room for an extra plain plate then there's likely room for an extra friction provided you can get enough 1.5mm plates to reduce the overall height and more friction plates should work better and for longer.
The Bucci slipper clutch assembly instructions with organic/aluminium friction plates, show the last 2 plates to be 2mm steels for road use. Sintered friction plates in the race version use a different combination. Andy
OK....done some thinking (yes, hard work.....did you notice the smell of burning? )...I'm gonna beg now.....anybody got a spare 1.5mm flat plate they don't need? Beer vouchers & postage offered in exchange! Cheers S23
I just don’t get this fixation with stack height. I’ve changed clutch packs countless times and never had any bother. I’ve always gone with broom handle technology. I take each plate out and slide it on a broom handle (or similar) then simply replace new like for like. Works for me
