Master cylinder and vacuum brake booster

A master cylinder and vacuum brake booster wherein a rear shell for the booster is disposed adjacent a vehicle fire wall and a front shell for the booster is adapted carry the master cylinder, the booster including a diaphragm which is pressure responsive to generate an input force to assist operation of the master cylinder during braking, the master cylinder including a flange adjacent the front shell and cooperating with a bolt or the like to secure the master cylinder to the front shell so that reaction forces opposing the input force are transmitted from the master cylinder to the front shell, characterized in that said front shell extends from a radial inner portion to an axially-extending radial outer portion to define a substantially unidirectional and substantially frusto-conical uniform profile from said inner portion to said outer portion, said master cylinder flange including a substantially tapered surface matching said profile and said bolt defining a longitudinal axis which intersects a longitudinal axis for said master cylinder and vacuum brake booster when said bolt secures said master cylinder to said front shell so that said front shell uniformly distributes the reaction forces over said front shell during braking.