By the way, Mark, by using the wrong parts on the brakes on my Piet, I found that some O-ring materials aren't happy with brake fluid. I realize that aviation (red) brake fluid isn't the same as DOT automotive fluid, but here's a reference that might help in general: http://www.efunda.com/glossary/design/oring/design--oring--chemical--brake_fluid.cfm I thought viton was pretty much unaffected by the things that are common around our airplanes but it sounds like brake fluid is not one of those and neither is Buna-N, which is also very common for O-rings. I know you're a stickler for using the correct part in every case (especially if it means having to drain brake fluid and get up inside the cockpit to get to those cylinders to replace O-rings if you don't get them right), but yours look large enough that a precise fit may be close enough if you can find them in the right material.
Oscar Zuniga Medford, OR
