Hi, great write up! I've had some clutch judder come in this season which has ruined my usual good starts. We checked the plates and they were fine yet the thing juddered off the line and the slipping actions were real grabby on the downshifts with the clutch lever snapping and smacking my fingers on each slip and grab inducing horrible backing in slides off the rear tyre..
I've done the drilling the three holes and as the basket is 1 year old now stepping had occurred on the grooves the plates sit in so whilst I was creating some swarf
drilling the 3 extra holes I thought I'd create some more by filing down the bumpy finish on the plate slots back to nice smooth one.
I was about to put it all back in with a new cable for good measure as well when I looked up the yoshi kit parts as I'm after much more slip on the downshifts than I was getting so far this season. They offer 2 replacements for the 3 reaction springs. 150N or 300N giving you either more or less slip either side of the standard 225N plates. Not having the $ to splash out on some (they aren’t cheap) I decided that as STM clutches only use one reaction plate and someone else from Oz posted that his only had 2 standard I would put it back together with only 2 lowering the pressure from 675N to 450N.
I adjusted the worm screw and the three slipper pins back up but I’ve set these to only 1 turn out rather than the usual 2 and ¼ as the gaps are now different with the 1 reaction spring missing (being .8mm in width and one thread being the equivalent to .8mm I worked out that running it at 1 turn out will be the equivalent to 2 turns with 3 springs).
So far so good no grabbing pulling away and lovely nice light clutch like I remember. Under load no slipping at all either but this was err just up and down the local road. I haven’t been able to test the slipping action on downshifts with this setup but will get the chance next week and will try and post an update.
Again great article and thanks to those that put the effort in.