Mastervac Brace
The master cylinder that converts the force applied to the brake into the hydraulic pressure is attached to the mastervac.  If the mastervac and the bulkhead where it is attached are moved by insufficient rigidity, the brake feeling worsens.  Specifically, this is the part intended to regulate the excess movement spatially and improve the braking reaction.  It is the evolved version of master cylinder stopper, isn’t it?