750 Posted May 2, 2015 Share Posted May 2, 2015 Hi all, The reason behind this question will make sense in a week or so, so bear with me! Are clutch master cylinders one in the same thing? I'm wondering if I could successfully fit an alternative to my bike, namely from a Ducati 900SS. Thanks for any info Link to comment Share on other sites More sharing options...
Member Contributer Dutchy Posted May 3, 2015 Member Contributer Share Posted May 3, 2015 No the piston diameter for one determines the pressures on the fluid. Like bigger bore engines have more torque Link to comment Share on other sites More sharing options...
Scottay951 Posted May 3, 2015 Share Posted May 3, 2015 A hydraulic clutch setup uses the same principle that your brake system does, you compress the brake fluid via the piston within the master cylinder. As Dutchy said, the size of the piston determines the amount of fluid you displace.If you're wanting to do a swap, using the master cylinder from a firestorm (that's what they're called overseas right?) is a direct swap since they both use the same size piston within the respective master cylinders. Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted May 3, 2015 Member Contributer Share Posted May 3, 2015 Unlike brake master cylinders, Honda clutch master cylinders are mostly the same size. 14mm, IIRC. So, yes, you can very likely swap them around. But do check, as bikes like the 1000RR have a 12.7mm master cylinder! In the front of every Honda Workshop Manual, the master and slave cylinder sizes are listed in the General Information section at the front. I suppose Ducatis are the same. You can also check for matching part numbers for m/c rebuild kits against those for known sizes, etc. Ciao, Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted May 3, 2015 Member Contributer Share Posted May 3, 2015 I can say, because I just rebuilt my clutch MC on my 1995 Ducati, that it uses a 13mm piston Brembo unit. If I recall when I was looking for parts, they have 12mm, 13mm and a 16mm unit but I don't think the later is was from a super sport, most likely from a later model Duc. If I remember correctly the coffin style reservoir units you can not rebuild, so not sure if their piston size is the same as the remote reservoir units. According to the guy at Bevel Heavan, the marking on the top of the lever assembly (not the actual lever) will tell you what piston size it is. I think I might have a pic of that on my computer if you need to see what I'm referring to, I'm using my iPad at the moment so no access to pic at this time. Cheers Link to comment Share on other sites More sharing options...
750 Posted May 3, 2015 Author Share Posted May 3, 2015 So bear with me on this one, as long as the piston diameter is the same then I can essentially use any master cylinder/reservoir? Link to comment Share on other sites More sharing options...
Scottay951 Posted May 4, 2015 Share Posted May 4, 2015 More or less, I don't see why not. Link to comment Share on other sites More sharing options...
bluewaffle Posted May 19, 2015 Share Posted May 19, 2015 so what would happen if you were to use one with a smaller ID like a 1000rr? Link to comment Share on other sites More sharing options...
750 Posted May 19, 2015 Author Share Posted May 19, 2015 Smaller would equate to more lever travel, I believe Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted May 19, 2015 Member Contributer Share Posted May 19, 2015 Yes, and in theory, more "power" with less "feel", but that's mainly for braking systems. A mismatch could result in the slave not moving enough to fully disengage the clutch. But it might not make any difference. Ciao, Link to comment Share on other sites More sharing options...
SoCal97VFR Posted May 22, 2015 Share Posted May 22, 2015 You may also need custom brake lines. Not all banjo bolts are the same size between manufacturers. Link to comment Share on other sites More sharing options...
750 Posted May 22, 2015 Author Share Posted May 22, 2015 Yeah was thinking that. I think I'm ready to give all this a go ;) Link to comment Share on other sites More sharing options...
bluewaffle Posted May 23, 2015 Share Posted May 23, 2015 what other bikes use a 14mm? Link to comment Share on other sites More sharing options...
bluewaffle Posted May 23, 2015 Share Posted May 23, 2015 ok someone quote me if im wrong. i have a cbr1000rr clutch master and it has a 12.7 piston which is smaller than the 14mm stock we have. this will still work but will have more lever travel? Link to comment Share on other sites More sharing options...
Member Contributer FJ12Ryder Posted May 23, 2015 Member Contributer Share Posted May 23, 2015 The smaller diameter will move less fluid when moved through the same distance. That means you will need to move the piston a longer distance to move the slave cylinder the same distance as the OEM. Most bike's lever distance is pretty much fixed, i.e. non adjustable for "total distance". So you may not have enough master cylinder stroke to move the slave cylinder the necessary distance to allow the clutch to disengage completely. And don't forget that it's possible that all clutch levers don't move the master cylinder piston the same distance. Possibly due to different positions of the actuating lever in relation to the pivot point of the lever. Farther away from the pivot will mean the piston will travel farther, and vice versa. Link to comment Share on other sites More sharing options...
Member Contributer MadScientist Posted May 23, 2015 Member Contributer Share Posted May 23, 2015 .... So you may not have enough master cylinder stroke to move the slave cylinder the necessary distance to allow the clutch to disengage completely. Very true. Remember 12.7 vs 14 may not seem like a lot, but volume displaced is changed by the square of the radius. In this case, 6.35 vs 7 seems even less. HOWEVER, this small change will result in roughly an 18% difference in the amount of fluid displaced over the same amount of lever pull, meaning that the clutch will disengage 18% less. It may work, but the engineers chose it for a reason. Do you know for sure if your clutch will disengage with 18% less travel? Link to comment Share on other sites More sharing options...
bluewaffle Posted May 24, 2015 Share Posted May 24, 2015 .... So you may not have enough master cylinder stroke to move the slave cylinder the necessary distance to allow the clutch to disengage completely. Very true. Remember 12.7 vs 14 may not seem like a lot, but volume displaced is changed by the square of the radius. In this case, 6.35 vs 7 seems even less. HOWEVER, this small change will result in roughly an 18% difference in the amount of fluid displaced over the same amount of lever pull, meaning that the clutch will disengage 18% less. It may work, but the engineers chose it for a reason. Do you know for sure if your clutch will disengage with 18% less travel? would adjustable levers remedy this problem? Link to comment Share on other sites More sharing options...
Member Contributer FJ12Ryder Posted May 24, 2015 Member Contributer Share Posted May 24, 2015 Not really, since the adjustable levers only change where the levers engage, they don't give you any more travel. Link to comment Share on other sites More sharing options...
750 Posted May 24, 2015 Author Share Posted May 24, 2015 What about going up a size in the MC for a set of calipers designed for something with a smaller MC. I imagine the bite will be a lot quicker, harder and have more feel? Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted May 25, 2015 Member Contributer Share Posted May 25, 2015 You want to discuss brakes now? Increasing the size of a master cylinder generally results in shorter lever action, more "feel" and LESS power. Ciao, Link to comment Share on other sites More sharing options...
750 Posted May 25, 2015 Author Share Posted May 25, 2015 oooh, ok, will stick to the tried and tested formula then! Link to comment Share on other sites More sharing options...
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