True so far,
If you have drums, and you go to '77-'78 brakes,
You will have to change the spindle, outer axle (Stub Axle) to work with the 6 bolt calipers,
That and a hand grinder and you are in business.
Once the stub axle and correct spindle are on, you can slap on the caliper bracket, then the hub, rotor, caliper, ect.
You WILL have to clearance the steering knuckle to clear the caliper, but that is just a little grinding with a 4" angle grinder.
Rotors are usually 1-1/8" thick, and despite what everyone thinks, there really isn't any difference in breaking power between the 'Thick' & 'Thin' rotor versions.
Since they both have the same brake pad swept area on the rotor, all the larger rotor does is resist warpage better if you constantly ride the brakes.
Since both versions were on the 1/2 ton pickups, your light weight, low speed Jeep isn't going to overheat the rotors unless you are retarded on the brake pedal.
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If you go later, '79-'86, you will have to change outer (Stub) axle, Steering Knuckle, and put the later stuff on the steering knuckle.
This will be a two bolt caliper bracket version with the 7/8" rotor.
This rotor is lighter weight, and has better cooling fins so it doesn't have to be as thick & heavy to do the same job.
Same swept area on the pads as the thicker versions,
But lighter and we all know that Unsprung weight is bad, so when you can drop weight on the rotor and bracket without loosing any breaking power,
It's always a good idea.
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Around '83 or so the Dana 30 in CJ's went to a 5 bolt lockout on the hub, and that means the hub only has 5 bolts instead of the earlier 6 bolt hubs/lockouts.
You can get replacment hubs with the 6 bolt variety to solve this problem, but it's more money on the conversion.
Personally, when I'm looking for a conversion set, I look for an axle from '79 to about '82 so I get the two bolt calipers with 7/8" rotors and 6 bolt lockouts/hubs.
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You WILL need to modify your current master cylinder or replace the master cylinder with one for disc brakes.
The drum brakes use a 10-15 lb. check valve that holds back pressure against the wheel cylinder in the front wheels.
It's there to keep the brake shoes in close contact with the drums so you don't have to pump the brakes to get the vehicle to stop.
You will need to extract that check/back pressure valve from the bottom of the master cylinder so the front discs don't drag all the time.
It's in the tapered fitting that seals to the front brake line, and you can extract it by threading a metal screw into it and pulling it out...
Some brake lines won't seal after the valve is pulled out, so you may have to hunt around for a 2 lb. valve to put in that hole.
Right now the correct master cylinder for that set up is $19.95 at Advance Auto with no core charge!
I stocked up with a couple for myself, one extra for manual brakes, two for power brakes while they are so cheap!
You will have to change the 'Soft Lines' between frame mounts and brake calipers.
Most of the ones I do, I go to braided stainless lines of smaller diameter than the factory 'Fat' lines.
I also get them 3-4" longer than stock so the front axle can flex a little more without the brake lines limiting articulation.
The smaller diameter, steel braided lines don't 'Swell' as much as the fiber/rubber (Stock Type) lines do, so you get a firmer brake pedal and better pedal feel.
Since disc brakes don't take near the volume of fluid to get the same stopping power, the smaller lines are appropriate.
They also help with front/rear bias, keeping the fronts from locking before the rears apply since with 4 wheel discs you normally don't have a 'Proportioning' valve, and the smaller lines will help delay the fronts a little so the rears have a chance to keep you in a straight line when braking hard.
Anyway, just some thoughts that might help the swap...