My rear brake lines finally rusted out where it runs up under the bed in front of the rear wheel. I've been putting off a major overhaul since the rear calipers and rotors are badly rusted. Rather than band-aid it, I'd like to press forward with an upgrade.

The existing single diaphram booster/master is marginal with the 32s. I have 1992 Crown Vic calipers and rotors in the back, so would an upgrade from something with rear discs more sense? Perhaps from a Grand Cherokee? I don't know what would be a mostly direct bolt-in. Both the rotors and the calipers are pretty rusty and in need of replacing. Is there a kit that might swap something better in there? Or should I dive even further into the rabbit hole and scope out the junkyard for something better than my D35 non-c-clip with 4.11 gears?

The Comanche has a proportioning valve in the back that changes rear braking based on payload. I have the arm fixed in the position for max braking back there. I'm thinking I should just eliminate it, and the return line that runs back to the prop valve under the hood. I'd need to swap to the XJ prop valve, or whatever prop valve comes with whatever I swap in for an upgraded master/booster.

 

Coupla things. 99 to 2004 Grand Cherokee booster/master from the junkyard with the flexible lines included.

Ditch that valve you're calling a prop valve. Run one line to the rear for the brakes from the master cylinder, through an adjustable prop valve, eliminating any factory stuff.
Connect the lines that go to each front wheel together with a union and get fluid directly from the master cylinder.

 

Thanks. Do you still need to modify the rod end at the brake pedal if using a WJ master and booster in a Renix? I was planning to ditch that rear valve and return line, and if I had problems with the rear locking up then add a wilwood valve in the rear (I doubt I'll have that issue though).

I actually had a WJ 98 master and booster I got real cheap from DeadJeeps last year. It showed up with rusted through holes in the booster and I ended up tossing it and getting a refund.

 

You may have to drill it out, but you don't have to monkey around grinding it so the brake light switch works. There's a work around on that by replacing the brake light switch with a better one.

 

Not a direct bolt in but id argue it would be long term worth the effort of swapping in a ford 8.8. Can be found with factiry disc brakes, LSD and 4.10s. Leaf spring perches, shock mounts and a companion flange at the very least, wheel spacers too but exactly required.

^^ All of this ^^