I am no brake expert, but the rear TJ drum brakes just kinda suck.
I think one of the reasons is the brake combo valve limits the pressure to the rear to prevent rear brake lock up in a panic stop. That is fine if you are going forward. But it sucks big time backing down a steep hill in 2wd when the front axle is unloaded and the front wheels lock up and the rear brakes don't do crap.
How much braking force can you get by just using your parking brake?
98 TJ, 4.0, 5 spd, 1" MM, 1" BL, RE 4.5" LA's, 36" TSL-SX's, D44/D44, ARB's, Atlas 4.2, etc