I have just replaced the clutch springs on a streetfighter with the correct oberon kit (0117) and i dont think it is quite right. the pressure plate is on correctly and the clutch works but the springs appear too compressed resulting in a stiffer lever and the lever doesnt come back to the bar. to me it looks as if either the springs are too long or the pressure plate is wrong as it has an older design jhp plate on it. so heres the question..... there are two spring kits for ducatis... what is the difference between them and what are the differences in pressure plates if any?
I wasn't aware of different springs or pressure plates either, is the pressure plate mark lined up with the correct drum pillar?
YEP, ALL THAT IS RIGHT AND I HAD TO TAKE THE SLAVE OFF AS IT WOULDNT PUSH HOME. THE SPRINGS LOOK TOO COMPRESSED AND THE PRESSURE PLATE ONLY MOVES ABOUT HALF OF WHAT I WOULD EXPECT WHICH IS WHY I THINK ITS HARDER TO PULL AS THE SPRINGS ARE MAXED OUT. AS A PROCESS OF ELIMINATION I WONDERED IF THE PLATE HAD THE WRONG OFFSET IM TRYIBG TO
It sounds like your clutch pack height may be too thick. The pressure plate would be sitting outboard making the springs look like they are compressed more. Also, the slave cylnder would already be slightly outward, hence when you pull the lever, it wouldn't go fully to the handle bar as it would have reached it's full extension before that point. There could be one other cause. The 6 bolts holding the springs in place could be too short. That would mean that the clutch springs would fully compress before the clutch lever reached the handle bar, stopping the lever short. Also because the springs were semi compressed when the clutch lever is fully out, your lever would be stiffer. Clutch pack height should be about 38mm iirc.
TYPING ON PHONE AND ITS MESSING UP...... ANYWAY, WONDERING IF THERE ARE DIFFERENT OFSETS FOR PRESSURE PLATES BUT I THOUGHT THEY WERE ALL THE SAME IF NOT THAT, IS THE DIFFERENCE IN THE SPRING KIT JUST THE COLLAR SIZE?
OK, MAKING SENSE WITH PACK HEIGHT BUT IM SURE ITS SPRING RELATED. THE BOLTS ARE NIPPED UP TIGHT SO EVEN WITH LONGER BOLTS IT WOULD HAVE THE SAME RESULT. WEIRD. ITS THE SAME SORT OF SYMPTOM IF THE PLATE ISNT ALIGNED ONLY IT IS. HMMM
No, because you may be fully compressing the springs before the lever reaches the bar. I had a similar thing happen to me on my 1098s. I think I changed from a 30mm length bolt to a 35mm bolt to cure it. I'm not sure on the size as it was a while ago, you may want to check that. So with a 30mm bolt for example, if the bolt was screwed in 10mm before it stopped, I'd have 20mm of lateral movement on the clutch plate, with a 35mm bolt, I'd have 25mm of movement.
It's possible that the new springs are wound to a different spec than the original so that the pull may well be heavier
That's incorrect. If the bolts are too short, then the spring will fully compress as you pull the lever. The spring then has nowhere to go, so your lever will stop short. I've had this happen. A longer bolt meant that the spring was under less initial compression and could travel more. I fitted a DP slipper to mine and found this using the original bolts. Bolts 5mm longer cured the problem. Imagine having the springs fully compressed from the off, pull the lever and how far do you think it would move?
Will check it over tomorrow afternoon. It very well may be the bolts but I will be comparing the spings too. They are approx 85% compressed before pulling the lever.
If the bolt securing the spring cap is tightened to the recommended 5Nm, the cap is clamped to the spring post, the spring is constrained at one end by the spring cap and at the other by the pocket in the plate effectively preloading the spring. The clutch action moves the pressure plate compressing the springs as it does so. Spring lengths and rates are selected to provide the required force and not be coil bound during operation. Springs length is 38mm, those from aftermarket vendors can differ. The 1098 used a different spring cap that is 2mm longer increasing the preload by this amount, this is probably the cause of the OP’s problem. A 2mm thick washer inserted between the spring cap and post will restore the designed preload
Im not following. If you add a 2mm washer wont the spring be even more compressed? Im going to have another look at it today and if I cant figure it out I will be declaring Oberon stuff a load of old balls, after all its just a friggin set of springs.
No, by adding 2mm between the spring cap and post, you decrease the preload by that amount. I'd be interested to know the length of the springs you took out and the Oberon items.
The 1098 springs are different to say the 996. They're not as heavy and a little longer. There are a few different stock spring specs in use now. There are also several different spring caps being used now to. Aftermarket aren't taking this into account and it's creating more of these type of problems. Length of the cap screw has no bearing. It clamps the the cap to the post as already mentioned. You can fit spacers under the spring cap to lessen the preload on the spring and give it more room to compress before it goes coil bound but be careful not to space it too much as the cap will hit the clutch cover....
Ok im getting it now. So the washers just shim the cap out so when the bolt is tightened to spec it tightens to the washer rather than the post. Bigger picture is they were a birthday present so the last thing I want is to give him the wrong part. Sounds like Oberon have the wrong spring spec. Can anyone recommend ones that are correct as to be honest im not happy shimming the things as its not my bike and would rather get him the correct ones.
There may be something in this as regards Oberon springs. I used them when I fitted my slipper as I wanted stainless springs with an open clutch cover. When I initially fitted them, the cups were recessed inside the pressure plate and the springs fully compressed before the lever reached the handle bar. This is why I went down the route of slightly longer spring bolts. Now the cups sit just slightly proud of the plate and the springs work fine.
If fitting longer bolts moved the position of your spring caps, I'd check that the screws haven't bottomed out in the spring post rather than screw the cap down fully on the post. The screw length should have no bearing on the spring height.... It's slightly off topic, but most aftermarket springs are based on the old spring dimensions and weights. This can affect how the slipper works. The clutch springs are a secondary load on the slipper mechanism and heavy springs can force it to slip late or not at all under all but the heaviest of loads. Sigma slippers for instance specify 1098 springs be used so that they work properly. I ran Speedymoto stainless springs in my corse slipper and had to set the pack quite thick to compensate for the heavier loading.
I get this thinking. On mine, when the bolts are tightened, they bottom out into the post, the length of bolt left determines the spring height. I guess other people's experience is that the cap sits flush against the post. If I try this, my spring fully compresses before the clutch is fully pulled in. I guess it may be an Oberon spring thing.
