Hydraulic clutch f-up


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I made a 25mm clutch slave cylinder a while back and bought a 9.5 mm master cylinder to use with it. I hooked everything up, but in testing it found I only had 1mm movement on the slave cylinder piston, so, obvioisly the 25 mm piston slave cylinder was to big.

I had a couple of 20mm hydraulic seals lying around, so next I made a 20mm slave. A thing of beauty: 6061 ally body, stainless piston, hydraulic ram seal, and instead of using a circlip to keep,the seal in place I made cover to keep the seal from popping that also doubles as a dust seal. Ae beautiful piece of work, even if I do say so myself. But, when I went to hook it up I found the master cylinder had jammed. Managed to get it apart but found the seals had expanded and when I pulled the piston assembly out, one of the seals was damaged. Obviously the master was meant to use brake fluid, not mineral oil as I had used.

So I looked for a repair kit, only original KTM kits were available for big bucks with no garantee it will fit. So, all in all, a monumental f-up.

So, it's back to a cable clutch and the slave I made is destined for the bin, along with the master.

In fitt'ing the hydraulic slave I had to modify the clutch cover, so now I have to see ifI can repair the clutch cover to fit the original plastic screw actuator.

Modifying bikes ain't eaay!


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At $50 a pop, nah, don't think so. I will keep aneye out for some new 'affordable' seals though.
Tha'ts the problem with the Chinese: You never know what you are getting, they don't differentiate between 7/8" and 22mm, and apparently don't differentiate between brake fluid and mineral oil.

I'm now spinning up aluminium bushes to fit in the clutch cover so I can refit the screw actuator. If I had a Triumph actuator with the three balls, I'd look at fitting one of them, they were pretty foolproof.