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Master Cylinder/Booster Upgrade, Larger Calipers?


NAXJA Forum User
I’m reading about master cylinder/booster swaps to accommodate 4 wheel discs and possibly larger calipers. I have a disc brake 8.8 rear in my 96 already and the brakes are otherwise stock. It works fine (actually it works really well). I’m getting ready to swap in a Wagoneer front Dana 44 and want to make sure the master cylinder pushes enough fluid.

I’m reading about 95-96 XJ, 95-98 ZJ, and WJ swaps. Is the difference between the 95-96 XJ and ZJ the booster and proportioning valve? The part numbers for the 96 XJ MC and 97 ZJ MC are the same and both are listed as a 1” bore. Does this mean my stock master cylinder will likely handle 1/2 ton front calipers?
I don't know the waggy calipers, but I'm running KJ rears, WJ fronts, my 2000 booster, and a Durango master cylinder and my brakes are awsome!
Oh, and a 2000 proportioning valve!
I re-read some of my old posts. The WJ has 1.890" x 2 pistons, the KJ has a 1.890" piston, and the Durango mc is 1.125".
I’m reading that the stock 1” master cylinder will work but the Durango mc This s better? I might run it stock for a while to see how it is. I like the idea of getting it on the road sooner.
I can tell you the '97 ZJ MC is the same as your "96 XJ MC, but the boosters are different on the pedal side of the equation. I just converted Varmint #1's '92 XJ to run a booster and MC from a ZJ. I had to modify the rod to get the pedal height correct. I went that route because I did not want to have to mangle the firewall flange in order to fit the WJ booster.