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Rear disc brake swap-prop valve question


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I'm going to be putting ZJ disc brakes on my MJ soon, hopefully this will be the last of the brake upgrades I will have to do to the MJ. I currently have a WJ Master cylinder and Booster, and the braking is pretty good, but the parking brake is terrible, and I'd like to improve that as well as the ease of service to the braking system. One question though. I know that disc brakes require more pressure to operate than drum brakes, and I've heard here that the ''proportioning valve'' that is by the master cylinder on MJ's only distributes the fluid and does not actually regulate pressure, and that the pressure is regulated by the load adjusting rear prop valve, is that true, or does both the master cylinder distribution block ( :dunno: ) as well as the rear prop valve limit pressure to the rear brakes?

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I'm going to be putting ZJ disc brakes on my MJ soon, hopefully this will be the last of the brake upgrades I will have to do to the MJ. I currently have a WJ Master cylinder and Booster, and the braking is pretty good, but the parking brake is terrible, and I'd like to improve that as well as the ease of service to the braking system. One question though. I know that disc brakes require more pressure to operate than drum brakes, and I've heard here that the ''proportioning valve'' that is by the master cylinder on MJ's only distributes the fluid and does not actually regulate pressure, and that the pressure is regulated by the load adjusting rear prop valve, is that true, or does both the master cylinder distribution block ( :dunno: ) as well as the rear prop valve limit pressure to the rear brakes?

 

The distribution block under the master is just that - for distribution. The proportioning valve that regulates brake bias to the rear wheels is the stock load leveling valve. I have Explorer rear disk brakes (w. an excellent internal drum ebrake on the rotors), and elected to retain the load leveling valve as I haul loads occasionally and it works. Everyone here badmouths it, I don't care, I think it's just a matter of people not knowing how to adjust it. Suggest you install your rear disks, retain the rear load leveling valve, then test and see how it goes. You are correct stating that the rear disks require a bit more bias so I fabbed an adjustable rod to fine tune it here: http://www.comancheclub.com/forums/viewtopic.php?f=9&t=17968&hilit=adjustable. My brakes work great under all conditions.

 

But if your load leveling valve is fubared, bypass it and either plumb in an XJ front prop valve or an aftermarket inline from Wilwood or someone. Plenty of info on that. :D

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My load leveling valve works fine, but ever since the SOA, I never made a new rod to adjust the prop valve and have it just zip tied up in the right position. I might have to make a new rod light what hornbrod has, and fab a new bracket to mount it to on the axle as I am running an 8.25.

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