What causes the slave cylender to fail?
 

so saturday on my way to work my clutch felt funny, so when i got there i looked under my truck and sure enough, brake fluid was drippin from the bell housing. after work, no clutch. drove it to the shop and i pulled the tranny and replaced it, second one within a year. last january i replaced it also. truck was back on the road by midnight saturday night. but my question being what causes the slave to go out?

I'm also interested in the responses....anyone?

Same as any other hydraulic cylinder: heat, vibration and contamination.

I suspect it's mostly contamination from the clutch dust working its way into the seals.

Did all the cylinders come from the same supplier? Same brand? That and everything StrangeRanger said.

Do a complete fluid flush. Easiest way to do this is in a shop with a power bleeder rig. When my slave went at 60k, the fluid that came out was black and nasty.