Wilwood High Volume Tandem Master Cylinder - 1 1/8in Bore Black. Wilwood's Tandem Aluminum Master Cylinder is available in 2 bore sizes 1.00" and 1-1/8"; and 3 finishes, plain, ball burnished and black e-coat.7/8 bore master cylinders are designed primarily for manual applications and include a pushrod. The 1 bore can be used in manual and power assisted applications and does not come with a pushrod. The 1-1/8 bore is designed for use primarily with power brake applications, either from vacuum assist or hydraulic assist systems. They're designed for mount flanges from 3.22" to 3.40", common measurements for most domestic cars and trucks from the mid 1960s to present, and offer fluid outlet ports on both sides of the bore. The stroke is set at 1.10 with a volume ratio of 2:1 between the primary and secondary chambers. Machined from high-pressure die castings, each master cylinder weighs only 3lbs, a 75% weight savings over most cast iron OE type master cylinders.