I made the switch to 4 wheel disc and bought a kit from strange engineering... They explained the theory about the master sending pressure to the FRONT wheels first and then the rear,, and they also talked about the surface area (footprint) that the front vs rear tires have.. The correct answer was to buy TWO pressure gauges and I FORGOT THE SPEC,,but,, I screwed a pressure gauge in the front and rear bleeder screws and adjusted the proportioning valve accordingly..