Well after several attempts at getting good brakes on this build we finally hit on the right combination of parts. Originally we had a 1 1/16" bore Corvette style master cylinder for disc/disc brakes combined with a YJ bellcrank and a 8" single diaphragm booster that resulted in weak brakes. Oh it stopped, but they were soft that rolled to a stop and couldn't lock up the tires. At first we blamed it on bad bleeding, low vacuum or the use of silicone brake fluid. Bought a pressure gauge that showed we were only getting around 700 psi. Definitely not enough for discs. We then switched to a 15/16" bore master cylinder from Classic Performance Products part #M-C1516-L that got us more pressure (1000

psi) but increased the pedal travel and foot pressure to the point of just off the floor. Scary to say the least and you could still not lock up the tires. A switch to a 9" dual diaphragm booster from Speedway Motors part #910-33054 netted us the results that we were after. Short pedal throw, reduced foot pressure and you could actually drag the tires. This thing now stops with authority and confidence with no bias lock up. A proportion valve may not be needed. Some modifications had to be made to the booster rod which was too long to be used with the YJ bellcrank. It was shortened and re-threaded to allow the use of a heim joint which got fastened to the bellcrank. It was still too long but could

not be shortened anymore, so 15/16' x 1" aluminum spacer blocks were milled up to space the booster away from the bracket. Luckily the 4 threaded studs were plenty long to make this work. In retrospect a complete CJ bellcrank/booster/master cylinder is available but none with a dual diaphragm booster or a 15/16" bore master cylinder. Considering the fact that we have a Frankenstein braking setup and are not using stock CJ brakes but rather larger J10 disc brakes up front and equally larger Isuzu Rodeo disc brakes in the rear we still might of had problems.