VW Bug, Super Beetle, Ghia and Thing Master Cylinders Stock Replacement or 4 Wheel Disc Brake. Stock replacement master cylinders for stock drum brake systems or if you have upgraded to disc brakes master cylinders with a larger bore. Bug, Ghia and Thing have basically the same chassis and the master cylinders are the same for the model years except Super Beetle these are different. 1958 - 1966 master cylinders for use with front disc brakes and rear drums has a larger bore with residual valve removed and needs a Bus style screw on reservoir or adapter. It is recommended to convert 1958 - 1966 models to the 1967 - 1977 style master cylinder for 4 wheel disc brakes. It is also recommended to upgrade the stock 1967 - 1977 models or 1971 - 1979 Super Beetle master cylinder to the larger bore master cylinder when converting to 4 wheel disc brakes. Also available is the rubber grommet for the reservoir inlet on 1958 - 1966 stock master cylinders. DOT 3 brake fluid only.