I think most people, myself included, will steer you in the direction of doing a WJ knuckle swap. It is a steering/brake conversion which results in much better steering geometry and much larger brakes. However, it is much more involved than swapping out calipers for larger ones. It requires cutting and welding. The result is over-the-knuckle crossover steering (moving away from the factory under-the-knuckle inverted-y style) as well as much larger dual piston calipers and larger rotors. It is possible with 15" wheels with little backspacing but 16" wheels are much easier to fit.

There are other options without doing the knuckle swap. Check out this thread that CobraMarty put together:

https://www.cherokeeforum.com/f67/17...0-44-a-222937/

 

ZJ rear disc swap would and be cheaper. Otherwise the WJ knuckle like above. I'm getting ready to do ZJ swap with all new lines. WJ, later, if I need it. I like the idea of over the knuckles.

 

Good point, I overlooked the rear. I have KJ discs on mine. They helped a bit but not nearly enough to leave me satisfied.

Ideally, you'd do rear discs and larger calipers/rotors in the front. Being a 99, you already have the better booster/master cylinder.

 

I'd go ZJ rear discs first.

 

I also have 35's. Initially I went for disc brakes on my Chrysler 8.25, worked pretty well. Swapped to an 8.8 rear end with discs (similar braking power)
The problem is the front brakes aren't that much bigger than the rear discs from the Explorer. I installed some Powerstop Z36 "Extreme Truck & Towing" pads which have really good intial bite, and good manners when both cold and hot. Plus they have an FF friction rating which is good. Very happy with these pads, nice and quiet and not too much brake dust.

Still, I feel like the front brakes aren't big enough. If you search for CobraMarty's posts, he has a "budget" big brake setup that uses Durango calipers I think, but you can piece the kit together on your own and save some cash possibly
https://www.cherokeeforum.com/f67/17...0-44-a-222937/

There is also a guide for 15" wheels, but if you are upgrading you might as do it once and do it right. All things considering, $1000 for a BBK (big brake kit) is not really that expensive.

Definitely convert to rear disc brakes first though, drum brakes are just a pain in the rear

 

Hahaha.. love it.