Joji: I was not aware the stock TCS M/C was stepped! Do you happen to recall what the diameters are? (I tried to back stock M/C diameters out of your numbers but keep getting a larger bore for the fronts than the rears, which I think is wrong way around.)
Regarding the economics of sleeving vs Spitfire, the way I pictured it going is I buy someone’s junk TCS M/C for $50, machine a 304 SS sleeve myself ($20 for 7/8” x 5/8” SS tube blank and tube of Permatex sleeve retainer), turn the pistons down myself, buy a Spitfire rebuild kit for the .700” seals ($25). So, in my head I’m into it for $100 + my time. Honestly, I have about a 50% confidence level I could make this work, which is why I’m not going to experiment on my own perfectly good M/C.
Brian: I thought about your idea of using innards from a Spitfire M/C in the sleeved Girling, but the lengths and location of the piston flanges would have to be the same as the Stock M/C. This is why I’d still like to get my hands on an old TCS M/C to reverse engineer it.
I’m very interested in your take on pedal travel. I actually love the short throw on my current brake pedal (applied with he-man force) and realize I would be giving that up with the small-bore M/C. So, you find .75” is the Goldilocks diameter? What Europa version do you have and did you make any other brake mods?