| Author | Message | ||
     Tone |
Hi, I'm wondering if anyone can tell me what the spring plate in the clutch pack is there for? The most I can figure out is that it is maybe there to counteract the effect of centrifugal force on the clutch plates when the clutch is spinning at high speed, but that's just a guess, and if accurate, I still don't know what it means :-) | ||
| Sloppy |
A spring plate provides the frictional force on the friction/steel plates to transfer force through the clutch. If there was no spring plate then the clutch would spin as there would be nothing to keep the plates to transfer the energy from the clutch to the tranny. The spring plate is a very common application of the diagpram clutch -- came into strong vehicle use during '70's. http://www.centerforce.com/clutches.tpl?cart=12114 77468443724&subsection=clutchtypes# http://en.wikipedia.org/wiki/Clutch Press your palms with extreme force together and rotate one hand -- your biceps are acting as the spring plate. This is a disengaged clutch (acting as a solid coupling) -- both hands rotate. One hand acts as the driving force (engine) and the other as the clutch pack (drive). Now partially press your palms together and rotate one hand -- your hand will "slip", this is an engaged clutch. One hand is moving at a different rate than the other. You are releasing force off of your hand the same as you are releasing the force from the spring plate to the discs. Feel the heat? That's the affect of slip and why we use oil clutches to keep the plates cool. Ducati, BMW and cars use dry clutches and "slipping" should be kept to a minimum on these. Centrifigal force clutches are typically used for small motor applications (scooters) or drag applications (completely different designs but similar laws of physics are used). Centrifugal force applies more force on the circumference and applies more force to the clutch -- the idea being that an engine at higher rpm produces more power than at lower rpm and hence needs a clutch to provide more force to transfer power to the transmission. I saw your previous post -- the spring plate (diaphragm spring) has been in use with great success for DECADES. In fact, many people like them over centrifugal clutches as the clutch pull is much easier. Imagine trying to engage a centrifigal clutch at peak rpm while you're shifting gears... There is likely something very simple that you missed while assembling the clutch. It's clearly not a design problem, but an assembly problem. Take it to an HD shop -- I've had to do that a few times. The labor rate your paying also includes the years of experience that they have. (Message edited by sloppy on June 06, 2008) | ||
| Al_lighton |
I don't think he is referring to the diaphragm spring or pressure plate. I think he is referring to the judder plate. Near as I can tell from talking to the folks at Barnett, the judder plate is there to make the initial bite when releasing the clutch lever smoother. Without it, the clutch can engage in a more jerky fashion, or can make a scroiching sound. (Yea, I made that word up....but say the word "scroich" and that's what it can sound like). I've run extra plate clutch kits without the judder plate and don't have a problem without it. I've had some scroiching noises but they seem to be harmless. Which is more than I can say about that g*dd#%mned disintegrating spring plate and it's bunch of brass rivets that came loose and destroyed my clutch basket. Al | ||
| Tone |
sorry I misstated myself. I didn't mean the diaphram spring - that part is clear to me. I meant to ask what the heck the friction disc that has an integrated spring is for. That thing has me puzzled. Based on what I've read on this board, it is no longer used in any Buells as of 2003. On my 2002 S3T, you have steel discs and friction discs like in any other bike, however the friction disc in the very middle of the basket actually consists of two friction discs which are joined together by some springs (flat springs, not coiled.) One guess I have is that as RPM increases, the centerfugal force somehow forces these two joined friction discs apart slightly, therefore reducing slippage of the entire clutch basket at high torque. But that's only a guess. It could also/or be that the function of this special spring friction disc is to give some of the clutch basket a slight nudge when the clutch is engaged, thereby increasing slippage when slippage is of course actually desired. But that's also only a guess. ---edit--- You posted at the same time as me Al. Thanks for the info. Hmm that is certainly a possible function of the spring disc/plate/whatever we wanna call it. If that is the only function of the spring disc/plate, then I have to say that sounds like a kludge of a design. If there is too much bite when the clutch disenages I would think that it would be possible to modify the clutch design so that it disengages at a different rate. Of course, certain pragmatic considerations were obviously not always on the minds of the engineers who designed this stuff... Take the location of the transmission oil drain plug, for instance... right above and obstructed by the muffler... Was that absolutely necessary? Probably not : ) (Message edited by tone on June 06, 2008) | ||
| Sloppy |
Ooops. Al's correct. The "grenade plate" serves the same function as a spring washer or springs in a dry clutch setup. It dampens the load on the clutch thus making it easier on the drivetrain and easier to operate. Kind of like a cush drive on the rear drive of some bikes (my Kawasaki had a big rubber block). Without the grenade plate the clutch engages very quickly -- most consumers like clutches with a "slower" operation so it's easier to feather the clutch. You appreciate a slower clutch window when you're stuck in traffic on a steep hill -- think San Francisco during rush hour. I don't know if you can call it a bad design -- mine looked perfect after 30,000 miles. I think it depends on the application that you use it for. |
