tankygsy Posted February 22, 2012 Report Share Posted February 22, 2012 Hi folks, Need someone with experiance of txt pros. I replaced the clutch on my 2007 280cc pro with a dp clutch from Gas Gas motos uk. Kev at gas gas reccomended not to use ATF fluid as the packs swell with this oil. I'm now using putoline light gear oil. Problem is I find the clutch a bit too progressive. The clutch kit came with 2.0mm steel disks. These were fitted and the clutch springs are at the lowest position (15.5mm spring distance). This should make it more snappy and stiffer at the lever. Fitting thinner disks and increasing the clutch spring measurement will apparently make it even more progressive! I'm thinking of swapping my oil to ATF again, to try and make the disks swell. Or Increasing the master cylinder bore. Or I'm even tempted to try adding an extra fiber disk and steel plate (giving me a 4 plate clutch), of course carrying out the mods to get the extra disks fitting correctly. What do you guys think? Quote Link to comment Share on other sites More sharing options...
slack Posted February 22, 2012 Report Share Posted February 22, 2012 Hi tankygsy,i have a simaler problem on my 05 Raga when relising the clutch leaver the clutch slips for a few seconds then bites.This i find very iratating as when you want to do some big steps you cant as the slip prevents this from happining.I am going to pull the casing off again & try replacing the o rings in the top hat to see if this cures the problem,but i am running out of ideas. Quote Link to comment Share on other sites More sharing options...
pandelboy Posted February 22, 2012 Report Share Posted February 22, 2012 (edited) measure clutch pack and adjust with steel plates to measure between 9.75mm and 9.85mm and it should be cock on at that. use atf dexron iid thats mineral blend, been using that for seven years in pros and never had an issue. you can buy the plates seperate from gas gas uk in various thickness check out the website or i think apico are doing a set now with varying plates. Edited February 22, 2012 by pandelboy Quote Link to comment Share on other sites More sharing options...
tankygsy Posted February 22, 2012 Author Report Share Posted February 22, 2012 Hi paddleboy Done that chap, can't remember off the top of my head the clutch pack measure but I recall in to be around 10mm with the 2.0mm plates in. Manuals and gas gas videos suggest I should have a relatively snappy clutch with this set up but it is not at all snappy enough for me. Perhaps I am going outside the boundaries of stock snappiness. I'm leaning towards fitting a collar over the top hat slave cylinder (to increase the diameter) then fitting an oversize roller thrust bearing. This will reduce mechanical leverage and advantage on the clutch springs, if I go too far and lever becomes too stiff I can then use narrower plates or smaller diameter bearing / collar combo. I have access to machine tools so spinning a few custom parts is no problem for me. Quote Link to comment Share on other sites More sharing options...
laser1 Posted February 22, 2012 Report Share Posted February 22, 2012 Hi paddleboy Done that chap, can't remember off the top of my head the clutch pack measure but I recall in to be around 10mm with the 2.0mm plates in. Manuals and gas gas videos suggest I should have a relatively snappy clutch with this set up but it is not at all snappy enough for me. Perhaps I am going outside the boundaries of stock snappiness. I'm leaning towards fitting a collar over the top hat slave cylinder (to increase the diameter) then fitting an oversize roller thrust bearing. This will reduce mechanical leverage and advantage on the clutch springs, if I go too far and lever becomes too stiff I can then use narrower plates or smaller diameter bearing / collar combo. I have access to machine tools so spinning a few custom parts is no problem for me. If you've tried all the various pak/fluid combo's - Maybe you can spec a 05 or older clutch spring (Belville washer)as they are 20% stiffer than from 06 on. What happened to the German?? OEM Pak supplier they have been using since 05?? Did they go under? They are nonadjustable, but work well and can use ATF-F for a quick trigger. Not sure if the Surflex and DP fibers are as good at resisting swellage (if thats a word) Quote Link to comment Share on other sites More sharing options...
tankygsy Posted February 22, 2012 Author Report Share Posted February 22, 2012 Hi lazer Changing the belleville spring washer will just make it stiffer or softer. it won't change the dwell period of the clutch biting as this is determined by the clutch disk levers (the springs), and bore size of master cylinder. Quote Link to comment Share on other sites More sharing options...
laser1 Posted February 22, 2012 Report Share Posted February 22, 2012 Ive put many softer springs in them and when going from the 05 stiff spring to the soft one, the clutch does become noticeably more progressive. Similar to the difference between Type F and Dex III ATF. Wont make it a light switch - but will make it faster-as well as a stiffer pull. Quote Link to comment Share on other sites More sharing options...
laser1 Posted February 23, 2012 Report Share Posted February 23, 2012 Since the K of a spring = Force/Distance, it seems that the distance to achieve the force necessary to lock the clutch plates together (and thus drive the rear wheel) would be achieved in a shorter spring displacement by using a spring with a higher K. (Distance = F/K) and match my empirical results. Quote Link to comment Share on other sites More sharing options...
basher Posted February 26, 2012 Report Share Posted February 26, 2012 i found i hated the gas gas clutch myself personally having come from a sherco which doesnt have a progressive clutch. ive switched to light gear oil putoline, and changed my levers to the flexi ones. i went out today and yet still progressive i have actually been able to get ust to the bike and am starting to enjoy it. if i was you id sell up and get something different. whats the point heavily modifying the bike like your on about, think about resale. if the bikes not for you get something different Quote Link to comment Share on other sites More sharing options...
tankygsy Posted February 26, 2012 Author Report Share Posted February 26, 2012 No can do basher. Your logic makes sense but as an engineer I'm naturally programmed to make what I have better. All bikes have their bad features, seeing as the clutch is the only thing on my gasser that im not 100% happy with its a no brainer for me not to correct this. Any mod I do will not effect the resale value as the mod will be reversible of course, but a point well worth noting. Quote Link to comment Share on other sites More sharing options...
paulmac Posted February 27, 2012 Report Share Posted February 27, 2012 No can do basher. Your logic makes sense but as an engineer I'm naturally programmed to make what I have better. All bikes have their bad features, seeing as the clutch is the only thing on my gasser that im not 100% happy with its a no brainer for me not to correct this. Any mod I do will not effect the resale value as the mod will be reversible of course, but a point well worth noting. Have you tried polishing the inside of the Top Hat? Paul Mac Quote Link to comment Share on other sites More sharing options...
basher Posted February 29, 2012 Report Share Posted February 29, 2012 why not buy a s3 clutch cover they have the option on the amount of o rings to alter the clutches progressiveness. Quote Link to comment Share on other sites More sharing options...
peterb Posted March 10, 2012 Report Share Posted March 10, 2012 Hi tankygsy, As mentioned earlier, the clutch pack height determines the leverage from the "fingers" and the take up distance. When this is at the optimum height, there are only two things one can do to alter the clutch take up "dwell" either alter the master or the slave cylinder diameters. Easiest one is to change the master cylinder, instead of using the std 9.5mm bore master, replace this with a master cylinder from a TXT BOY which has a 12mm diameter piston, this will provide more clutch travel, with less lever travel, but with more force required. I used one of these larger cylinders for the 02 PRO to overcome the clutch case flex problem, it worked. Bye, PeterB. Quote Link to comment Share on other sites More sharing options...
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