a couple of brake questions.

my buddy just had a 91 cherokee given to him for FREE!!!!!! He is a lucky man, but the brakes are shot. i havent got to inspect it yet, but he makes it sound as if the master cylinder is bad. and he wants to replace the whole system. would the braking system from a 93 be compatible? id think so, but im not a brake guy so id thought id ask the Nation. :rof:

*edit* i just got off the phone with him. as of right now he needs rotars, and calipers. as for the drums go, he's inspecting them right now.

If he ends up needing a new master do the mc/booster upgrade. You weill alreaddy have most of it apart so might as well upgrade while you are there.
http://www.naxja.org/forum/showthread.php?t=903934&highlight=booster
http://www.naxja.org/forum/showthread.php?t=924285&highlight=booster
http://www.naxja.org/forum/showthread.php?t=63067&highlight=booster
http://www.4x4wire.com/jeep/tech/brakes/xj_wjbrakes03/booster/

There are many many more on this topic but these are the ones that I have saved

i did a 2000 grand cherokee booster and master swap on my 89 and the braking is night and day better. i have complete control when coming to a stop and if i need to, i can lock up my 31's without a problem.

as long as we're on the topic of brakes, why won't a front disc brake system fit/work on the reat axel? or will it? i've read about the ZJ disc conversion- so i figured there had to be a reason why people don't use XJ in the same application.

A braking system needs to have proper bias between the front and rear brakes to work properly and, above all, safely. Brake bias depends on a lot of different factors that I won't bother to list.

IN a nutshell, the front brakes do the majority of the work so they need to be bigger than the rear brakes. If the rear outbrakes the front then you run the risk of locking up the rear end far too soon and losing control (oversteer).

I think you might have been mis-understanding the basis of the conversion and thinking that the ZJ front brakes go onto the XJ rear axle. The ZJ disc conversion you have been reading about takes the REAR disc brakes off of a ZJ and puts them on to the rear of the XJ. The XJ never came with rear discs so that is why you never hear about ppl swapping XJ for XJ rears. Liberty rear brakes will work in the same swap as well.

Incidentally the only applications (that I am aware of) where the rear brake dimesions are close to that of the front are in rear engine Porsches because of the extra weight hanging of the rear end.

i get it... there are inherent properties of a brake set up that makes it suitable for rear brakes or front brakes. but i was a little confused about the ZJ conversion and appreciate the calrification.

that was exactly the type of answer i was looking for and very helpful.

thank you.

andy