About 8 years ago I had stainless steel pistons made by my local machine shop and installed them in White Post, brass sleeved cylinders that I have used for 16 years. I also used the ATE front inner seals that GI sold since they fit the tightest, and front boots that I bought from White Post, they being the only ones that actually fit tight to those small front cylinders. I packed under the boots with Red British brake grease and switched both my cars to NAPA silicone brake fluid. I was warned to flush all the old fluid out of the lines but wasn't as careful on one of my cars as the other. After about 4 years I noticed a leak in one of the rear cylinders on one car and found some black crud had built up on the brass cylinder walls. I cleaned it off, replaced the seals and two years later notice one of the right front cylinders on the same car is showing a minor leak. My other car is still perfect so I'm quite sure the black crud was because I wasn't as careful flushing the old fluid from that car and the crud is a reaction between the old fluid and the silicone. Those stainless steel pistons were so expensive to make that the cost I felt would be prohibitive so I never went into production of them. This was also around the time when GI was about to bring out their inexpensive ATE copies. Liability with a brake part was also a factor. I made 4 sets, two sets for my cars, one set for a car I restored for someone else and the forth set I sold to another owner. Be sure if you switch to silicone fluid to flush the old stuff out quite thoroughly.
I very much approve of using silicone brake fluid. If you do get a leak, it won't destroy your paint. I also like the fact that at least the NAPA silicone fluid is purple so is easy to level check in the fluid reservoir.
John Friese
67 White
67 Red
