1. We started up at the top by tossing the factory proportioning valve in favor of a Wilwood Combination Proportioning Valve (PN 260-11179). You always want 100 percent of the braking force going to the front brakes, but not the rear. If you have too much force to the rear brakes, they will lock up on you and send you into a skid. With all the modifications we’ve made to this Jeep, it was anyone’s guess how much force would be needed, hence the knob to adjust force to the rear brakes.