Rear disc on XJ C8.25" from a ZJ

Magus2727

Magus2727

NAXJA Forum User
Location
Draper, UT
With the old drums and 33" tires were not helping me stop and finally needed to get around to getting new shoes. Thought I might as well use the C8.25 29 spline rear end I have had laying around for the last few years to good use.

Grabbed the rear disc brakes off a 98 ZJ in the local junk yard.

Got all new pads and rotors. And ebrake cables.


Had to make the opening a bit larger on the backing plate. Used a few of the guides to get this far.




Some questions though. Is the rear brake line splitter block different at all from the drum vs disc?

Is there any special or correct way to adjust the parking brake before it's on the car? Guessing you want it to engage about 1/2 way through the ebrake levers motion?

I am going to see how the brake bias works as is, don't have the ZJ perprtional valve (forgot to get it as the junk yard).

Is there anything I have missed or need to watch out for?

Thanks.
 
I have never had the prop valve and never had a problem and you don't wanna be able to excessively move the rotor side to side where it contacts the ebrake otherwise the shoes won't engage it fully it's just like adjusting drums
 
Prop%20Valve%20Guts_zpsnkzvaqyg.jpg
 
Fastest way to adjust ebrakes: with wheel bolted on or rotor bolted on, adjust the star wheel until it's hard to turn the wheel/rotor (or you can't turn it at all) then back off the adjuster 5 notches. You're done. The brake line will be fine, there's nothing special about it. If throw some new brake hoses on there tho.
 
Thanks for the info.

I was looking at the soft lines and then started looking at replacements. Should a standard part store carry something like those or special order or from online? Not to mention I also can't seperate the soft line and hard line from the ZJ on one caliper.

Also thought about upgrading the rear main line to a SS line also. It will all be much easier to do when swaping the axle all in at once.

Might run to the junk yard then and grab the valve.
 
I have not been able to find the short rear ones that mount to the caliper. any of the kits for lifted jeeps also only have the 3 (two for the front and 1 for the main rear).

Do you know where I could find the short 6" caliper mount ones in SS?
 
Have you called any of the 4wd shops near you? Or you can go to any auto parts store and get SS lines in various lengths and threads. Pep boys would be my first stop if SS was a requirement since they are more about bling then the other places.
 
I have found a website called Toxic Off road that makes the rear short lines for $60 shipped which is only about $15 more than new rubber lines.

My Jeep is on the older side so not sure if replacing all the lines would be good since I will be flushing/bleeding the whole system.

I have not called any of the shops. Was not sure with the unique way the calipers have the lines connected would be a local option. On my other cars I am use to threaded inserts on the calipers. I have not seen this style of block mount before.

SS is not a requiremnt. Just in looking at SS since it's not that much more than new rubber lines.
 
cruiser54 said:
Prop%20Valve%20Guts_zpsnkzvaqyg.jpg
Click to expand...

About to go to the junk yard and pick up some parts. Do I just need the guts or the whole valve and guts? Looks like a simple 3/4" socket would be all I need (reason for the two wrenches being in the pocture...) to get the guts.

Edit: looks like it's a 13/16" size from another online tutorial. Can it be removed with a single socket? Don't have all my tools with me.
 
Last edited:
You'll at least want one wrench to pull the plug and another to hold the combo valve in place. If you take just the guts, you don't need to flare new lines to the ZJ combo valve. Much easier to just take the guts.
 
Grabbed the guts. All the pictures show the plunger as being red... the ones I got (checked two ZJ's) were silver. I am guessing that from the brake fluid eating the anodized color or "paint" that may have been on there to be red or yellow...
 
When you do your pads, grab pads and hardware kit from an 06 TJ (or Explorer, same caliper as ZJ). These pads use a steel overrider that eliminates the divots common to the ZJ brackets. A little tip I learned from Mr. Blaine the old brake guru from days gone.

Sent from my SGH-I337M using Tapatalk
 
The steel over riders are the bits that go between the bracket and the pad with? Well already got pads, Hawk LTE per the picture for the Xbox
ZJ specific. In cleaning up the brackets I did notice there is some notching in them. Thanks for the tip and if I have to ever replace the rears again I will go that route.
 
Getting the Toxic brake lines today. I have 1 Quart of DOT4 Brake Best Select fluid (per documentation is suppose to have some really good #'s for dry and wet boiling points). With replacing all the soft lines (front, rear, rear short), the proportional valve, front bleeder screws, and rear calipers that are drained is 1 Quart enough? Or will I use that much before I even start the bleeding process?
 
Quart should be fine but I always have a smaller bottle sealed just in case I need to top off. You want to really flush it out since you are going from DOT3 to 4. In your case, to get rid of all the 3, I would bleed in reverse order to flush out as much of the 3 as quickly as possible and then once you've bled the right rear, bleed again the the proper order (RR, LR, RF, LF). It's a bit wasteful but it ensures a complete flush and can help with excessive air that can get in when doing swaps like this.
 
Thanks, I will work on the reverse order to help with the air.

I am not sure where you got the DOT 3 from? I have been running DOT 4 in the system for years since I have owned the Jeep, 100k miles back. It has DOT 4 in it and its mostly fresh stuff. last flush of the brake system was done about 6 months back.
 
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