firecapt Posted August 8, 2004 Report Share Posted August 8, 2004 I have an 02 Pro 280 that is set up wonderfully.. Everything is perfect EXCEPT the clutch has become very hard to pull at the lever... it operates well, it just fatigues the hand. Knowing how the clutch operates, I have my ideas about why it has become hard to pull. Does anybody else that has knowledge of this clutch have some thoughts? A hint about what I think is going wrong: The "spring" (which is actually a "ring") is the culprit. What do YOU think? I'll be calling the "parts house" first thing tomorrow and ordering the necessary items.. a ring at the least, an entire clutch pack at the most.. . thanks, W Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted August 8, 2004 Report Share Posted August 8, 2004 I don't know for sure but think a set of measured plates is the answer. Quote Link to comment Share on other sites More sharing options...
bikespace Posted August 8, 2004 Report Share Posted August 8, 2004 I don't know for sure but think a set of measured plates is the answer. Yep, think Dabster's right. Had mine go a few times. Very cheap, we're talking less than 30 quid from what I remember for the clutch kit. Plates need to be measured right. Back to perfect afterwards. Quote Link to comment Share on other sites More sharing options...
windlestone Posted August 8, 2004 Report Share Posted August 8, 2004 hi gas gas usa has a picture of the correct measurements for the clutch cage. you will probably only need to replace one plate. very cheap. look on this gas gas forum under exhaust yarghhhhh or similar and clutches for some reason are discussed in depth. Quote Link to comment Share on other sites More sharing options...
jtt Posted August 8, 2004 Report Share Posted August 8, 2004 I agree, check the pack thickness before ordering any parts. I'd be surprised if it had anything to do with the pressure plate (ring spring), but it is possible. It's a quick and easy job to pop the basket out and measure and inspect. At least that way you'll be sure what your ordering. Quote Link to comment Share on other sites More sharing options...
firecapt Posted August 9, 2004 Author Report Share Posted August 9, 2004 Thanks guy for your thoughts.. I have replaced the clutch pack before and understand the "measurement issue." More of my thoughts: I put a new clutch pack in months ago and the measurement was 18mm (good), now the measurement is 14 mm (bad). Now, with this type of clutch, if the fiber plates wear down/thin out, this critical measurement would get bigger. Something has caused the "fingers" to settle by 4 mm. It couldn't be a "wearing" of the fiber plates as the measurement would get bigger. It could be that the plates have "swollen" as this would cause the measurement to get smaller.. and this would be unfortunate in such a short time, although I do ride the bike about 5 days a week.. Another possibility is the ring (that acts as the spring) could be "flattening" out some and this would allow the fingers to settle down also, AND more importantly, I think the ring/spring would be harder to compress with the travel that was remaining in the spring/ring. This is what I think is happening.. well, i have probably bored you enough... I'll call the tech guru tomorrow and see what I can find out.. I will get the problem fixed, but I do want to know the detailed technical reason why the pull on the clutch lever is getting so hard.. thanks Quote Link to comment Share on other sites More sharing options...
the artist formerly known as ish Posted August 9, 2004 Report Share Posted August 9, 2004 Ho Capt, I thought by now you would of sussed the more you pull it the harder it gets Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted August 9, 2004 Report Share Posted August 9, 2004 I doubt there is a detailed technical explaination it is probably very simple as is the design of the clutch. My guess is the spring rate is not linear and you are in a stiff zone. No pun intended. Quote Link to comment Share on other sites More sharing options...
jtt Posted August 9, 2004 Report Share Posted August 9, 2004 (edited) You may very well have something there FireCapt. You clearly have a good understanding of the clutch system. Everything wears out eventually,so why not the spring I guess. I have heard of the swelling plate issues before. Not being a spring specialist, I would think that as a pressure plate type spring like this fatiques and gets "flatter" that the action would actually get softer as the leverage on the flatter surface would be greater? That being a non-linear rate, but a falling rate, rather than rising. That and the nature of the metal fatiguing would naturally make it softer I would think...but again, I'm no metalurgist I'd be very interested to hear your final findings. Please let us know. Out of curiousity...and because I know it will be one of the first questions your "guru" will ask....what oil are you running in the tranny? Edited August 9, 2004 by JTT Quote Link to comment Share on other sites More sharing options...
firecapt Posted August 9, 2004 Author Report Share Posted August 9, 2004 Well, more good info guys thanks .. I talked with Jim Snell today.. It sounds like the spring is not the problem, but that the plates may be swelling. (Gas Gas has produced 3 "generations" of fiber plates for the Pro, only the 3rd generation are not subject to swelling. My plates are 2nd generation). For oil, I have been using either Dexron III, or B & M Synthetic. As the plates swell the "pressure plate fingers/levers" move down toward the bottom of the clutch pack and a significant mechanical advantage is lost in the lever action. Hence, the harder pull. Jim also mentioned some possibilities of problems with the original 2002 clutch spring and pressure plate, but the explanation was very long and I have since replaced the original so I won't go into that here.. So, it looks like everyone's first thoughts were correct: the fiber plates (swelling) are to blame. I have some of the thinner metal plates on the shelf so I will install those tonight to see if I can get the measurement back up to 18mm. I will still order the "new generation" plates, but I want to feel the increase in leverage at the clutch lever tonight! I'll let you know how it all works out.. thanks again. Regarding the oil, Jim recommended only 2 types of oil: 1) regular Dexron III, or 2) GM Auto-Trac Synthetic He also said Mobile One ATF is NOT good... too sticky and if the water pump seal forms a leak, Mobile One reacts with the water to form a corrosive substance.. Quote Link to comment Share on other sites More sharing options...
windlestone Posted August 9, 2004 Report Share Posted August 9, 2004 firecapt while it's stripped check the nut holding the clutch cage is tight. it's in the centre of the cage. this can take up your lever action. maybe half the movement at the bars. Quote Link to comment Share on other sites More sharing options...
firecapt Posted August 11, 2004 Author Report Share Posted August 11, 2004 Alright. Latest on my clutch. I opened up the clutch pack and installed the thinner metal plates (1.3 mm and 1.4 mm). After installing these plates the new measurement was 19 mm. I put it all back together and poured the new oil in and took the bike for a spin. THE CLUTCH WAS SOOOO MUCH EASIER to pull!!! Yeah.. So, to sum up exactly what happened: My clutch fiber plates swelled, which caused the critical measurement to decrease,(pressure plate fingers to the clutch hub shoulder). This reduced the mechanical advantage which was seen at the clutch lever as a hard pull. So, now I will order the new fiber plates and PRACTICE, PRACTICE, PRACTICE Thanks, Wesley Quote Link to comment Share on other sites More sharing options...
jtt Posted August 11, 2004 Report Share Posted August 11, 2004 Glad to hear you got it sorted Wes. Quote Link to comment Share on other sites More sharing options...
bulsher Posted August 12, 2004 Report Share Posted August 12, 2004 What a Pain! Quote Link to comment Share on other sites More sharing options...
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