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KJ 8.25 Disc Brake Swap


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Hey guys I was instructed by @Pete M to write a new write on swapping disc brakes. This is my first write up and being one of the younger guys on the forum feel free to critic the write up.

**You can easily do this swap in a few hours, given you have the tools and are handy.**

 

First things first find your local salvage/junkyard and find a jeep liberty with rear disc brakes. I personally used an 04 liberty.

You are going to pull all the good stuff, backing plates, rotors if they are good, calipers (to use as cores for new ones), brakes lines, e-brake components minus the e actual ebrake cables because we will be re-using the stock comanche ones

 

If you are lucky like me the wheels will be off the liberty, so all you will have to do is take off the caliper, pop the diff cover, take the 8mm cross pin bolt out, push the axle shafts in, take out the c-clips, and pull the axle shaft out to give you access to you the backing plate. which should look like this....

BlXvCSs.jpg

 

undo the 4 bolts and everything should come out in one piece.

 

Now back to where you have your beloved comanche, set the rear up on jackstands and repeat the same process to pull the axle shafts out and expose the dreaded drum brake backing plate

dVj4v7F.jpg

 

its 4 bolts just like the kj backing plate, be sure to be use generous amounts of pb blaster, elbow grease and a hammer to knock off the backing plate.

once its all off, you can take your kj backing plate and mount it on your axle

 

rQMQvk7.jpg

 

Once the backing plate is one, you have to use your hammer once again and hammer out the old wheel studs as they are not long enough to mount your wheels and tires safely with the now wider mounting surface of the disc

Part numbers: the studs I used are the front wheel studs from a 1997 jeep cherokee dana30 they fit perfectly

OVrGaY4.jpg   WbVOGn4.jpg 

once you have the studs in, you can go ahead and reinstall your shafts

 

Now the only specialty tool you need is a double flaring tool found at most auto part stores. Yours may allow you to rent, but I had to purchase mine. It is a tool like this. 

qYU3PSJ.jpg ** I watched several youtube videos on how to flare brake lines before attempting doing this, and recommend you doing it as well.**

 

You have to swap the fittings on the kj lines because they won't thread into the distribution block on the 8.25. So you cut the end off the kj line and pull the old fitting off. Since I used the original fittings, it didnt slide the easiest over the kj line so I used a blow torch to heat them up, to expand them and slide it over the kj line. After the "new" xj fitting is on, match the brake line to one of the holes in the flaring tool and flare to your hearts desire. 

 

Once the flaring is done, you can carefully bend your brake lines and run them how you want them. I still have to fix mine as I want the line to go under the leaf springs but I wanted to get it hooked up and tested.

VHlDQCS.jpg 4jDA5Qt.jpg  hCv9ldb.jpg

 

After all this is hooked up, you can install your new pads, rotors and calipers. I went with the drilled and slotted flavor mostly for aesthetics and performance too

s4mk62z.jpg  W7PNyfm.jpg

 

Bleed your brakes and off you go. I really like how it feels with how little driving I have done around my neighborhood. I can't really compare the disc brakes to drum brakes because I never drove my jeep with drum brakes but from what I have read it is an upgrade over stock. 

 

If you have any questions, please let me know so I can answer them to the best of my ability.

Also let me know if you need more pictures

 

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  • Swampy changed the title to KJ 8.25 Disc Brake Swap

I forgot to mention how to hook up the parking brake...

 

They way I am going to do it is by first ordering new comanche parking brake cables because mine some how were fraying and no good

 

and ordering these little adapters made by The Flop Shop Offroad <---- hyperlinked the website

NYFHMfK.png   

 

The e-brake cable adapters should let you use your stock cables with out having to mess with much else. They can be found under the XJ category

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  • 4 weeks later...
14 minutes ago, TheDude said:

This far simpler than imagined it to be. Nice write up.


Sent from my iPad using Tapatalk

 

Yeah the only tricky part is reflarring brake lines but other that its bolt in

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the parts stores should carry some adapters and pre-made lines for those who are shy about flaring your own. :L:  

 

there is no good reason why everyone hasn't done this by now!  :D  

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  • 3 months later...
  • 1 year later...
9 hours ago, ValpoManche said:

So no grinding the backing plate like on the ZJ plates? If so, any KJ will do... right? No differences between KJ years?

No there is no grinding the backing plate. just pull of the drum backing plate and put the disc one in its place.

As far as I saw on the kj's the only difference was the earlier ones still had drum brakes. so I think 2004/2005 and newer have the disc brakes. 

 

I was satisfied with braking performance with the stock booster and disc at all 4 corners. If you do the dual diaphragm booster and the distribution block, braking performance will be greatly increased 

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