Brakes YJ brakes on a 77 cj?

[Phoenix827]

Hey all, just a quick question. Can yj disk brakes be used to swap the front axle on my cj from drum to disk?

 

[CJ]

Hey all, just a quick question. Can yj disk brakes be used to swap the front axle on my cj from drum to disk?

I hope I understand your question but because of the wording I am assuming you are asking about YJ parts on your CJ.
Yes YJ disks on a 77 CJ will work but it will require all the parts including the backing plates, mounting hardware, calipers, pads, rotors, hubs, spindles, and steering knuckles. You will also need a drum / dosk proportioning valve as well as a drum / disk master cylinder.
You will most likely have to do some minor mods like cutting or grinding because of the slight differences between narrow VS wide track Dana 30 axles.
The least amount of work is if can find a 78 - 86 CJ donor or an aftermarket conversion kit.