When I do the ZJ front disc brake swap, can I put my stock XJ front disc setup on the rear axle?

It might be a dumb question, but why wouldn't it work? Caliper on the wrong side? Backing plate?

What are your thoughts?

 

No such thing as a dumb question, the front discs normally mount onto the knuckle iirc. No knuckle in the back, and I don't know of a backing plate for them. You can very easily do a rear swap from a zj. I don't think you can use a zj backing plate, might be worth a shot for ****s and giggles, but if you're going to go through the trouble to pull all the other stuff to get to it you might as well just do the zj brakes.

 

What is the ZJ front disc swap? I'm curious.

 

You won't be gaining anything putting ZJ front discs on an XJ (same diameter and i think the same calipers too). Putting WJ front discs on WILL gain braking performance since they are larger diameter and use larger 4-piston (i think) calipers. The popular swap is to put ZJ REAR discs on the rear of an XJ. That swap is one that I always recommend. I did it and it's great. Some say to use the proportioning valve from the ZJ, I didn't use it and saw a huge improvement in braking. You might expect even greater improvement with the ZJ prop. valve. I was happy with what i ended up with so I never bothered.

 

That's why I asked. I've got the ZJ discs on the rear. I love it.

BTW, I just swapped the guts from the ZJ prop valve into the XJ and it worked better. Didn't even have to bleed the brakes.

 

Interesting, maybe I'll have to keep my eyes peeled for a ZJ prop valve and do that too. What parts get swapped over?

 

I'm going to be doing the WJ swap for the front.
It can add up, fast. But since you have to use the wj knuckles you also get a semi high steer. There's plenty of write ups online for it, when i get my taxes back i will be doing this.

 

3/4" wrench. Carefully remove the big nut. Out comes a spring, and a rod with a seal on it.

 

How does doing that not introduce air into the system? Seems like it would, requiring a good brake bleed...but if not, hey, that's even more awesome...

 

I have no clue. It worked for me.

 

Oops my bad, WJ on the front ZJ on the back, y'all are right. The WJ calipers are dual piston. But I was just curious if that was even possible, didn't seem like it would be worth the hassle. Thanks for the insight though.

 

Curious if what was possible? XJ front discs on the rear of an XJ? Anything is possible, but it really wouldn't be worth it considering the other options you could choose to get discs on the rear. I've got a grand total of like $70 wrapped up in the rear ZJ disc swap i did on mine. You could pick up an entire ZJ dana 35 for probably $100 and swap all the components over and scrap the rest. A WJ front disc is more involved considering you have to use WJ knuckles and calipers. Then use different unit bearings and rotors (with the correct diameter and offset) to keep the 5x4.5 bolt pattern. Then there might be some gymnastics to get the steering geometry right too. Oh, and thanks for correcting me on the # of pistons in the akebono WJ calipers....

 

Yep thanks for the info

 

It's just a guess, but I think the rotors would not work on the shoes for the e brake. I think that's the only thing you would need to check to see if front rotors work on the rear and the calipers being mounted on the knuckles also.