Hi Everyone,
I thought I'd share this so that anyone out there wanting to put discs on their J/K ram car can see what I've attempted and save themselves the trouble of duplicating combinations that don't work. I've tried everything and am tired of not driving my K because the brakes suck. I've had 4 wheel discs on the car and none of the combinations of master cylinders have given pedal feel that is remotely reassuring. Of course the issue is I can't get a traditional booster on the firewall and converting to the '62 and earlier over/under style bellows setup would require major surgery on the firewall of the 63 / 64.
I started with manual discs with a large bore master and had a high pedal that stopped the vehicle under normal driving conditions. If however I got distracted or had to otherwise stop abruptly in any panic situation I'm sure I'd flatten any Kia or Hyundai in my path while simultaneously shortening the front of my car. Pressure gauges installed at the calipers showed insufficient psi to properly activate discs. I switched to a smaller bore master cylinder and while the pressure went up, so did the required travel of the brake pedal. The end result of that was that while it was easier to apply the brakes there was not enough pedal travel, the pedal went pretty much to the floor and the car stopped no safer than the previous set up.
The next step was to plum the brakes through the remote slave cylinder. We did that not only running all fours through it but also just the front brakes through it; effectively having a power front / manual rear 4 wheel disc setup. Next attempt was to put the drums back on the rear under the assumption that eliminating the rear calipers would lessen the volume requirements and perhaps allow the discs still on the front to work. Nope... not happy with that either. So... all the discs are coming off and the drums going back on all four corners. Single reservoir master, through the slave cylinder, out to 4 drums. I'll just try to keep it out of snowstorms and off rain flooded roadways.
Needless to say the front and rear disc conversion will be listed for sale for someone who has room to put a nice powerful dual diaphragm booster where it belongs, on the firewall.
Mike Laiserin