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8.25 - ZJ rear disc conversion - PROP VALVE

X

xjbcca

NAXJA Forum User
Location
OK,BC,CA
Kinda new here, tried the search - some dirrection / advice would be great!

I've got a 92 on a 8.25 in my driveway
I've got a 94 ZJ rear break setup including booster and the works on my work bench.

Question: the proportioning (sp?) valve is for abs... which I would think all grands had if they had rear disc. The conversion seems easy enough, but...

any advice on adapting the Zj prop. valve (two lines out to abs- one rear - one front) to my Xjs non abs (three lines out - one rear, two front).

Any additional advice that you may have been hung-up on when doing the swap would be great too!

cheers
 
Usually the third port on the ZJ prop valve has a plug in it. It is basically the second port for the front circuit. Take a close look at it and you will see what I am talking about. You just remove that plug and it will plumb in just fine with your existing brake lines. Also if doing the ZJ rear disc swap if the backing plates came off a D35 you will need to open the center hole up to fit on the 8.25 housing. Other than that it is straight forward bolt on..
 
Put the disc. on & try it with the stock prop. valve. I haven't did anything with mine & it works fine. JIM.
 
Just swap the ZJ prop valve internals into the XJ's prop valve body. This way you dont have to mess with lines.

Use all of it including the end cap as it has a larger ID for the plunger.
 
OverlandXJ said:
Just swap the ZJ prop valve internals into the XJ's prop valve body. This way you dont have to mess with lines.

Use all of it including the end cap as it has a larger ID for the plunger.
Click to expand...


How would you just swap internals...??
 
Remove the bleeder/bolt on the front of the prop valve remove xj spring&valve, and put in the shorter ZJ spring&valve.
 
Clean-RC said:
Usually the third port on the ZJ prop valve has a plug in it. It is basically the second port for the front circuit. Take a close look at it and you will see what I am talking about. You just remove that plug and it will plumb in just fine with your existing brake lines. Also if doing the ZJ rear disc swap if the backing plates came off a D35 you will need to open the center hole up to fit on the 8.25 housing. Other than that it is straight forward bolt on..
Click to expand...

I figured it out when I got home that day... little too much pot smoking up here!
thank you good sir.
 
tcm glx said:
The write up does not talk about fluid loss....will you lose alot of fluid while doing this....
Click to expand...

good question. let me know about this idea guys - sounds better then running new lines or trying to find a fitting/adaptor.

cheers.
 
About 8 years ago I did a disc brake conversion; replaced the drum brakes on my 98 XJ 8.25 with '81 Cadillac Eldorado calipers including emergency brake actuator and 11" discs brakes off a Lincoln Versaille. Used the stock master cylinder/booster and removed the rubber seal off the proportioning valve regulator which supplies the rear brakes... The difference in braking is quite dramatic....
 
tcm glx said:
The write up does not talk about fluid loss....will you lose alot of fluid while doing this....
Click to expand...

If your vehicle has some miles on it, this is a good time to drain out all the fluid and refill it with new. Over time brake fluid goes bad, and your going to have to bleed the brakes any way when you are done. When I did my swap I let all the old dark fluid drain out.
 
JEFF said:
If your vehicle has some miles on it, this is a good time to drain out all the fluid and refill it with new. Over time brake fluid goes bad, and your going to have to bleed the brakes any way when you are done. When I did my swap I let all the old dark fluid drain out.
Click to expand...

i hope you didn't let the all the old fluid drain out through the bleeder valves! that could ruin all the seals in the braking system. you need to first suck all the old fluid out of the master cylinder reservoir with a turkey baster or a big syringe, clean out all the junk with a rag, fill it up with new fluid, and then bleed it until the new stuff comes out.
 
Nihil said:
i hope you didn't let the all the old fluid drain out through the bleeder valves! that could ruin all the seals in the braking system. you need to first suck all the old fluid out of the master cylinder reservoir with a turkey baster or a big syringe, clean out all the junk with a rag, fill it up with new fluid, and then bleed it until the new stuff comes out.
Click to expand...


I let it drain down until it was almost empty, topped it off with new fluid and blead the brakes. Why would letting the fluid drain out throught bleeders ruin the seals in the brake system?
 
When we use the power brake bleeder machine at work we always suck out old fluid in the MC, fill with new, then bleed the entire system one corner at a time. It's just a good idea to fill the MC with new fluid instead of bleeding the dirty fluid in the MC through the whole brake system.
 
JEFF said:
I let it drain down until it was almost empty, topped it off with new fluid and blead the brakes. Why would letting the fluid drain out throught bleeders ruin the seals in the brake system?
Click to expand...

if you looked at the old fluid in the MC you would have seen it was really dirty. there's all kinds of crap that builds up in there that you don't want in your brake lines.
 
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