1998 Jeep Wrangler No rear brakes

are you saying you want the rear brakes to lock up? or are they locking up without intent? If you are trying to do this, I assume your jeep does not have abs, and if so you have already had it disconnected, you can accomplish rear brake lockup a couple of ways, 1. using the emergency brake when you want this to happen, or 2. you can get a little more advanced, they make a proportioning valve you can install or have installed, this controls the amount of brake pressure either to the front or the rear wheels, which ever you want to do the most braking.you can have the adjusment selector located within reach to change as desired...hope this helps. I do not recomend this for on road use!!!!!!!!as rear brake lock up can be very dangerous and cause loss of veh. control I assume you are using this for offroad trailing, or decent offroad...good luck and be careful..