18. Center to center was about 4¼-inches, so that’s where we’ll mark the center of the clutch master cylinder mounting location. We’ll also want the brake and clutch rods parallel and level so that the masters are level on the firewall. This is why we drilled out the clutch pedal arm to match the existing hole on the brake pedal for the linkage. A hole saw is used to cut the center opening for the clutch master cylinder, then the mounting holes can be marked and drilled.