On my 3rd clutch master cylinder. Why??

[Gregor]

I had master & slave cylinder replaced in 4/00 (shortly after purchase of FJ40). Replaced master cylinder again in 4/05 & again 6/08. It has never leaked before going out either.

I don't know much about clutch so have always taken to mechanic for repair. I don't know if the first 2 times I replaced w/ rebuilt parts or not. This time I got new Toyota master.

Could it be synthetic fluid causing the problem? Maybe problem related to being chevota?

I have searched & there are literally a couple hundred posts about master cylinder, but not really finding anything causing repeated problem except perhaps synthetic fluid.

Anyone have ideas or seen a thread that could answer my question?

Thanks!!

[Gregor]

Forgot to mention rig details:

77' FJ40, Chevy 350, 4" suspension lift, power steering, disk brakes, toy tranny

In notes I took in 2000, I wrote that slave cylinder is Chevy - not sure if that is correct or not

[Radd Cruisers]

That's not too abnormal for wear, really.

When I ran DOT 5 synthetic fluid, the bore wear was insane. Moved back to DOT 3 and new parts and it's much better. Keep your DOT 3 changed out every 2 years or more.

If you want longer life, get a good cylinder sleeved with stainless steel. The stainless won't corrode, and it's smoother (less wear) for the seals to run along.

~John