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Rear Disc Brake Problems.....Sway bar link trouble

Cipey

NAXJA Forum User
Location
Beachmont, MA
I finally rolled my xj out of the shop yesterday with its completely rebuilt 8.8 rear end.

Problem 1.....stopping is an adventure, i have read and been told that my xj 's proportioning valve is not set up for disk brakes and removing one from a grand cherokee with rear disc should fix this problem...well i removed a complete master cylander and prop valve from a GC....should this fix the problem? Is there anything else I can do?


Problem 2... I added another 2 inches of lift to my rig bringing it to 5 or 5 1/2 inches of lift. I noticed that my front wheels and my sway bar end links have moved back an inch or three toward the firewall. I also noticed that my control arms, the lower ones in particular have a greater angle toward the vertical than before...

need to know if replacing the control arms with a longer set will helf solve this problem. Rough Country seems to have those adjustable long arms at a resonable price. can i just replace the bottom ones first? will that help? or should i just frig it and do all four?

Thanks

Cipey
 
The lift has indeed made the tires move closer to the fire wall due to short control arms. You should replace the lowers with the correct length for the lift, or preferably an adjustable set. IMO a set of uppers would be needed at this time as well to correct the pinion angle after you get the lowers on. Adjustable uppers are the only way to go if your trying to "dial in" the proper pinion angle etc. As far as the braking problem, I hope that someone responds to that b/c I have a 8.8 that is ready to go in and I too have a brake set up from a Grand Cherokee. Also remember, if you dont already have an adjustable track bar, you will need it since you went to 5"or 5.5" of lift. Those little relocation brackets are not set for that much lift, actually they are a bad idea all together.
 
As far as the brakes, the dual diaphram booster and the ZJ proportioning valve will work with your brakes. before you do that though, try to take apart your current proportioning valve and remove the plasting ring around the valve shaft. That will increase braking pressure to the rear tires. Give it a shot before you do the whole ZJ set up, It's probably worth it. Also, the F-350 brakes are a good upgrade too.
 
Cipey, what year is your XJ?

On my 94 i installed a 95 XJ Dual Diaphram Booster, ZJ 4WDisc master cyl and ZJ 4WDisc proportioning valve internals with the o-ring, and now have better braking than the 94 XJ components minus the o-ring.

On my son's 94 YJ he has excellent braking with his 8.8 w/discs with no hydraulic modifications.
 
John B said:
Cipey, what year is your XJ?

On my 94 i installed a 95 XJ Dual Diaphram Booster, ZJ 4WDisc master cyl and ZJ 4WDisc proportioning valve internals with the o-ring, and now have better braking than the 94 XJ components minus the o-ring.

On my son's 94 YJ he has excellent braking with his 8.8 w/discs with no hydraulic modifications.


my xj is a 98
 
I agree. Upper and lower adjustable arms are a great addition and will certainly help the handling/ride, and alignment. Getting the front pinion angle dialed in without messing up caster is always a problem without them. You are ahead of the game if you have a pre 2000 with the high pinion front end.
My 2000 with 8.8 and disks has much better breaking without any mods to the hydraulics at this point. I will have to try removing the ring in the proportioning valve to see if it can be even better.
Remember to retighten everything after several miles and again after the first 50 or so. Use Loctite!
Adding length to the sway bar link will get the sway bar back close to stock position, but as long as it does not hit anything, it really doesn't care.
 
XJ&TJ4ME said:
The lift has indeed made the tires move closer to the fire wall due to short control arms. You should replace the lowers with the correct length for the lift, or preferably an adjustable set. IMO a set of uppers would be needed at this time as well to correct the pinion angle after you get the lowers on. Adjustable uppers are the only way to go if your trying to "dial in" the proper pinion angle etc. As far as the braking problem, I hope that someone responds to that b/c I have a 8.8 that is ready to go in and I too have a brake set up from a Grand Cherokee. Also remember, if you dont already have an adjustable track bar, you will need it since you went to 5"or 5.5" of lift. Those little relocation brackets are not set for that much lift, actually they are a bad idea all together.

my track bar is a-OK......i have a rough country 3 inch lift and added daystar rear shackles and front spacers at 1.75. plus the 8.8 axle gave the rear a small pop in lift..

i haven't added the master cylander and prop valve just yet from the gc. i will prob do that after i "F" with the prop valve

cipey
 
Then you already have the dual booster. If your gonna "F" with the prop valve just install the ZJ internals and be done with it. Use all of it including the end cap.
 
For the price of control arms you would be btter off with drop brackets at that height!
 
RCP Phx said:
For the price of control arms you would be btter off with drop brackets at that height!
I hear ya...the Rough Country dial ups for about 150 a pair are pretty good good for the price, unless someone k nows of something diff or a better for less. I agree with the drop brax but i am the type of guy that if something is sticking out underneath i will get it caught on something. call it cipey's law!!! perhaps if i put those baby skids on 'em, i don't know. i put in a couple of three grand into my rig in the past two months between parts and labor...not counting my own sweat when i have the time.

selarep said:
Also, the F-350 brakes are a good upgrade too.

tell me about these F-350 brakes...gas or diesel? I got tons of 350, 450 550 stuff at the shop...diesel stuff...


Cipey
 
Cipey said:
tell me about these F-350 brakes...gas or diesel? I got tons of 350, 450 550 stuff at the shop...diesel stuff...

Cipey


Here is the 86 E350 MC and the 88 XJ booster mated together and installed in my 93 ZJ.




Here is the ZJ MC. Notice how the pushrod is part of the MC via some kind of funky tube. It is part of the MC and not removable without a bunch of work.



Here is the ZJ booster. Notice how there is no pushrod sticking out the end. It is a funky setup with a short nub of a rod inside. The XJ booster mounts right up with no modification to the old ZJ spot. Even attached to the pedal exactly the same way.


Here is the XJ MC. It looks just like the E350 setup. However the mounting holes on the E350 need to be drilled out to 9/16 and a hair shaved off the outside of the ear.


Here are the SOA YJ lines I used to get a bunch more leangth. Even at full droop with no shocks they are WAY long.....



Here is the Part Number of the E350 MC. 25 bucks!



Here is the joining of the two front lined and it totally bypasses all the ABS junk. I am not running a proportioning valve either since I want my brakes working about 50/50 anyway.​
 
So thats what I will do....im just gonna pull out the xj master and prop and replace it with the zj's master and prop.....although they look the same, the numbers on the cylander and sensor on the prop valve are different....not too worried about that sensor....but the number won't mean anything?

Hope not!!!



:patriot: We are never EX Military, just Former Military:patriot: brothers (and sisters) in arms.or ex arms or former arms...UNITE!!

Cipey
Currently the RepoMan
Formally the Navy Submarine Man​
 
Cipey said:
So thats what I will do....im just gonna pull out the xj master and prop and replace it with the zj's master and prop.....although they look the same, the numbers on the cylander and sensor on the prop valve are different....not too worried about that sensor....but the number won't mean anything?​


Hope not!!!​



:patriot: We are never EX Military, just Former Military:patriot: brothers (and sisters) in arms.or ex arms or former arms...UNITE!!​

Cipey
Currently the RepoMan

Formally the Navy Submarine Man​
Ah, a seaman. I was a DC-men.

Yeah the e350 prop works good. its cheap and easy. and the ZJ should be an upgrade as long as its from a V8.
 
Cipey said:
So thats what I will do....im just gonna pull out the xj master and prop and replace it with the zj's master and prop.....although they look the same, the numbers on the cylander and sensor on the prop valve are different....not too worried about that sensor....but the number won't mean anything?

Hope not!!!



:patriot: We are never EX Military, just Former Military:patriot: brothers (and sisters) in arms.or ex arms or former arms...UNITE!!

Cipey
Currently the RepoMan
Formally the Navy Submarine Man​


Cipey, got your PM. On that prop valve...the internals are what is different. The plunger has a different OD, which does not fit the XJ end cap..you need to use both. The spring is also a different length.

I dont see why you cant just swap the whole ZJ prop valve since you have everything removed.

The ZJ valve....was it from a 4 wheel disc setup?
 
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