Brake cylinder bores should be roller burnished to finished size. This cold forms the metal surface and leaves the best surface finish for the seals to run against. My suspicion is that the boring operation on the existing master cylinders is breaking into an area of porosity within the casting, and that area is destroying the seals.

.roundy roundy smoothing

I'm interested to see what the fix is for the radiators- I've seen talk of swirl pot- that's not going to help the welds splitting on the tanks...

Simon @ Sifab.co.uk

Sifabtemporary@gmail.com