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Rear Disc Conversion

X

xjrrrdx

NAXJA Forum User
Location
Denver
Well I did the ZJ conversion on my 96 XJ 8.25. The install was cake but I have an issue of a very soft pedal. I can stop in a safe manner, but the pedal if very soft. I have a small leak in my front left caliper but I could not buy a new one thanks to me losing my debit card. Anyway, I doubt that small of a leak will make the pedal that soft anyway.

I bled the brakes twice, once with the jeep off, and one with the jeep running. And the pedal is just as soft. I am using the junkyard calipers/pads, but I did get new rotors.

Any ideas on why the soft pedal??

Oh Ya I didnt use the ZJ prop valve.
 
soft pedel is pretty much air in the lines. Keep bleeding until you get brand new fluid from the master coming out both rear calipers, and then do the same for the front.
 
And make sure the calipers are on the correct sides. Bleeder valves go on the top.
 
Doubt this helps but here:
disc3.jpg


Ill check if the calipers to make sure.

When I did bleed I went from back right, back left, front right front left. The backs had old fluid so I will bleed till I get clean fluid in the rears. And hopefully tomorrow I will replace my leaking caliper.
 
I did the ZJ disc conversion on my D44 and when I was done the pedal felt "weird". The pedal also went lower before it stopped. It wasn't spongy and it was completely bled with new fluid. It as low and "weird" like I couldn't get a feel for how much foot pressure equated to stopping power. Kind of hard to describe I guess. I swapped in a ZJ proportioning valve and it made a big difference.

There is a mod where you can pull an O-ring out of the stock XJ valve but there are a few different opinions as to how good that really is. Some people were happy with it and others not. Supposedly drum brake prop valves keep a residual pressure after you realease them and the discs will drag slightly if you use the original XJ valve. I don't know if that's true or not, just something I read on the 'net. And as we all know if you read it on the 'net it MUST be true. :)

So for the $5 the junk yard wanted I went with the ZJ prop valve and have been way happier with my brakes.
 
xjohnnyc said:
And make sure the calipers are on the correct sides. Bleeder valves go on the top.
Click to expand...

Well like an idiot I had them on upside down. It didnt help the mushy feeling though. I drove around the block after got up to about 30mph then slammed brakes and it just lurched forward. Tomorrow after training Ill head to the auto store and get the front caliper.

When I re-bleed is it best to have the jeep running or does it even matter?

I guess I will be back on here if the pressure does not increase on the pedal. Where is the little o-ring located at so I can remove that temporarily until I get a ZJ prop valve.
 
xjrrrdx said:
Well like an idiot I had them on upside down. It didnt help the mushy feeling though. I drove around the block after got up to about 30mph then slammed brakes and it just lurched forward. Tomorrow after training Ill head to the auto store and get the front caliper.

When I re-bleed is it best to have the jeep running or does it even matter?

I guess I will be back on here if the pressure does not increase on the pedal. Where is the little o-ring located at so I can remove that temporarily until I get a ZJ prop valve.
Click to expand...
You don't have to replace the entire valve, it's easier (the Grand's mounting bracket is a little different and dosen't just "bolt on") to just remove the guts from your disc/drum valve and replace them with the Grand's innards then, make sure and bleed the valve after doing the swap-------Hans
 
Not a good idea to remove the O ring as if that front leak got much worse for instance, you would lose ALL brakes and you no longer have the front and rear isolated from each other.
My site shows you how to do it, but you have been warned, and change the to a ZJ valve as well. www.go.jeep-xj.info
Just wondering if I should remove that write up due to the safety risk involved even though I do warn about it?? Dont what some one to sue me!!
 
Gojeep said:
Not a good idea to remove the O ring as if that front leak got much worse for instance, you would lose ALL brakes and you no longer have the front and rear isolated from each other.
My site shows you how to do it, but you have been warned, and change the to a ZJ valve as well. www.go.jeep-xj.info
Just wondering if I should remove that write up due to the safety risk involved even though I do warn about it?? Dont what some one to sue me!!
Click to expand...

No worries man. I had only had thoughts of removing the O ring to see if it helped the pedal pressure. But after scouring the net and your site it says the prop valve makes no difference until hard braking. I am actually off to go buy a new front caliper right now anyway since I am on the road I will pick up a prop valve.
 
Well the good news is I replaced the front caliper and that small leak was causing the soft pedal. I had to order a prop valve but everything is a-okay now.


Well actually there is one thing. Last year I had a emergency and had to take the XJ to a midas to fix my brakes. They replaced the front left caliper (the leaky one) so when I go to take it off one of the caliper bolts is missing. They stripped out the hole and now nothing fits. Im going to retap it later this week but yeah thats it.
 
Gojeep said:
Not a good idea to remove the O ring as if that front leak got much worse for instance, you would lose ALL brakes and you no longer have the front and rear isolated from each other.
My site shows you how to do it, but you have been warned, and change the to a ZJ valve as well. www.go.jeep-xj.info
Just wondering if I should remove that write up due to the safety risk involved even though I do warn about it?? Dont what some one to sue me!!
Click to expand...

just put a FREAKING HUGE bright colored disclaimer stating that all the stuff on your website is for "educational purposes only" and that it should only be done by proffesional certified people etc..etc.. bullsiht bullsiht and you'll be fine.

if you've ever looked up other "building instructions" on the internet, you'll start seeing that disclaimer alot. lol
 
scorpio_vette said:
just put a FREAKING HUGE bright colored disclaimer stating that all the stuff on your website is for "educational purposes only" and that it should only be done by proffesional certified people etc..etc.. bullsiht bullsiht and you'll be fine.

if you've ever looked up other "building instructions" on the internet, you'll start seeing that disclaimer alot. lol
Click to expand...

Marcus,

Scorpio_vette has a good idea just to cover your a**. I would hate to see you remove anything from your site. It's an excellent place for good info and I know a lot of people appricate it.
 
I had a fellow XJer who knew more than me what to write a few years ago give me this to put on the bottom of the index page where it has been since:

Disclaimer:
All things shown or advice given on this site is to give you ideas of what can be done. They may not be suited to your vehicle, or your level of skill or even legal in your state or country. You assume all responsibility for any modifications that you make to your vehicle, and must understand the consequences of each modification you make. I cannot be held responsible for your interpretation of these articles, or your implementation of these modifications. It is up to you to make sure anything shown needs engineering approval or advice before using it.

Hope that covers my arse!
​

 
You should put a disclaimer on the disclaimer. So you can't be sued if someone uses you disclaimer but get sued anyway. :)
 
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