ZJ rear disks

[dagr8tim]

Has anyone actually done it? I know there's a ton of write up's out there, I'm looking for somebody that has done it.

[ike]

i did it on mine...:rolleye0012:




JY zj caliper mounting brackets and calipers for cores, and kept the hoses
jy zj proportioning valve

from the parts store...
2-rebuilt calipers (remember cores)
new rear pads
new parking brake shoes
10-new front xj studs for rear axle
8-grade 8 bolts and nuts to mount backing plate to axle
2-new rotors

open up the axle holes to fit the 8.25 housing (maybe 5 min with a round file)
remove the abs pump, re-bend brake lines to fit proportioning valve and the soft lines on the axle

there are more than a couple of ways to hook up the parking brake, your choice

bleed system

there ya have it rear discs... :congrats:

[dagr8tim]

i did it on mine...:rolleye0012:




JY zj caliper mounting brackets and calipers for cores, and kept the hoses
jy zj proportioning valve

from the parts store...
2-rebuilt calipers (remember cores)
new rear pads
new parking brake shoes
10-new front xj studs for rear axle
8-grade 8 bolts and nuts to mount backing plate to axle
2-new rotors

open up the axle holes to fit the 8.25 housing (maybe 5 min with a round file)
remove the abs pump, re-bend brake lines to fit proportioning valve and the soft lines on the axle

there are more than a couple of ways to hook up the parking brake, your choice

bleed system

there ya have it rear discs... :congrats:

Awesome. I snagged the backing plates, brackets, and bolts. For what they wanted for calipers, I can order new ones from Rock Auto cheaper and they don't charge a core. I also snagged the cap, spring, and red needle valve thingie that was in the front of the break junction block. I'm assuming that's the proportioning valve parts I need.

Here are my questions so far:
- I didn't snag the rubber lines. If I buy them new, will they attach to the hardline that runs down my 8.25?
- Are ZJ rotors plug and play, or do they need to be opened up?
- How do I disassemble the backing plates to do new hardware and parking break shoes?
- The junction for the ebrake looks the same, can I just order new ZJ cables and hook them up?

Right now I need to disassemble the backing plates and brackets and clean them up before I do anything.

[XJ Wheeler]

Looking to do the same, 8.25 disc swap. Definitely be watching this one for more info.

[WyoXJ]

I know that the 35 is not as good as the other rear axle's. But its what I have right now. So my question is can I do a disk brake swap to it?

[bluedragon436]

If you want to do a disc swap on your D35 it will be pretty easy.. as that is the same axle that the ZJ has that you would be pulling the parts off in the Jy anyways... The only thing you'll need to do is work the parking brake hookup, and still need to pick up different lugs.. the rest of the replacement parts like new pads and rotors is up to you.. but I would go ahead and do it at the same time you do the install..

[bluedragon436]

Looking to do the same, 8.25 disc swap. Definitely be watching this one for more info.


I know that the 35 is not as good as the other rear axle's. But its what I have right now. So my question is can I do a disk brake swap to it?

I know this won't help the OP. but wanted to post this link for the above two folks... WyoXJ this is more of a writeup for the Ch8.25, but will be the same process for your D35.. minus having to open up the center of the backing plate.. Hope this link helps you two on your decision to do this upgrade as well as completing it..

[Mudderoy]

I know that the 35 is not as good as the other rear axle's. But its what I have right now. So my question is can I do a disk brake swap to it?

Before you spend much time on the D35 I would investigate swapping to a C8.25. I hear you can get them for $100 to $150 and it's a direct bolt in. Then you have a axle that you can make modifications to and you really won't be in the same situation of having to do it all over again when you break it and swap it.

Some people do fine with a D35 and other it snaps with moderate tire size and moderate wheeling.

Personally I wouldn't waste my time (much less my money) on modifying a D35.

[dagr8tim]

Before you spend much time on the D35 I would investigate swapping to a C8.25. I hear you can get them for $100 to $150 and it's a direct bolt in. Then you have a axle that you can make modifications to and you really won't be in the same situation of having to do it all over again when you break it and swap it.

Some people do fine with a D35 and other it snaps with moderate tire size and moderate wheeling.

Personally I wouldn't waste my time (much less my money) on modifying a D35.

To the person you replied too. If I had a 35, I'd just invest in an 8.8 with disks and LSD and be done.

I realize the 8.25 is bolt in, but the 8.8's can be fairly easily found with 4.10's.

[bluedragon436]

To the person you replied too. If I had a 35, I'd just invest in an 8.8 with disks and LSD and be done.

I realize the 8.25 is bolt in, but the 8.8's can be fairly easily found with 4.10's.

I would love to do that swap myself one day.. but all depends on where you are and what you can do yourself.. I can't find a 8.8 with 4.10 in my area.. and when I have.. they didn't sell cheap at all.. then you got to pick up the brackets and have them welded on unless you can do all that yourself.. which I def. can't do... not yet anyways.. That is the only thing keeping me from swapping even my 29spline 8.25 for a 8.8 w/ 4.10,LSD and disc brakes... all of which are upgrades I plan to do to my 8.25... cheaper for me to do the upgrades to my 8.25 than the 8.8 swap in my area... maybe if I were further south or west I could do it on the cheap though...

[Mudderoy]

From what I have read this is a really easy upgrade, the only hard part is getting the emergency brakes hooked back up. I have read people use and not use the proportioning valve.

This is something I WILL be doing to my rig.

[dagr8tim]

I would love to do that swap myself one day.. but all depends on where you are and what you can do yourself.. I can't find a 8.8 with 4.10 in my area.. and when I have.. they didn't sell cheap at all.. then you got to pick up the brackets and have them welded on unless you can do all that yourself.. which I def. can't do... not yet anyways.. That is the only thing keeping me from swapping even my 29spline 8.25 for a 8.8 w/ 4.10,LSD and disc brakes... all of which are upgrades I plan to do to my 8.25... cheaper for me to do the upgrades to my 8.25 than the 8.8 swap in my area... maybe if I were further south or west I could do it on the cheap though...

I completely understand. I've got a beatup 29 spline 8.25 with LSD in the garage, and a really clean spare housing. For me, I think I'm going to slowly clean and build the LSD 8.25 and then be able to swap it when I have a weekend free without too much downtime.

If I didn't have all that, I would be investing in an 8.8 and getting it setup and built.

[dagr8tim]

From what I have read this is a really easy upgrade, the only hard part is getting the emergency brakes hooked back up. I have read people use and not use the proportioning valve.

This is something I WILL be doing to my rig.

I think the cooling & the braking were marginal from the factory in the XJ. Then when you add bigger tires (more rolling momentum), you are really behind the 8 ball.

Don't know if I needed the porp valve or not, but I pulled it and the yard usually doesn't charge for small BS parts that they cannot easily figure out what they are. So I got it for free on top of everything else. I figured why not have it just in case.

[bluedragon436]

From what I have read this is a really easy upgrade, the only hard part is getting the emergency brakes hooked back up. I have read people use and not use the proportioning valve.

This is something I WILL be doing to my rig.

Yeah I have found online during my searches that you can either pick up the emergency brake cables from a Liberty or you can make your own setup using clamps & cable.. but well worth the work.. as far as the proportioning valve.. most folks said they were able to continue running their 97+ XJ valve... but the ones that swapped the ZJ valve in later, said they did notice a bit of difference.. so they said it was worth swapping too if you can get it from the JY..




I completely understand. I've got a beatup 29 spline 8.25 with LSD in the garage, and a really clean spare housing. For me, I think I'm going to slowly clean and build the LSD 8.25 and then be able to swap it when I have a weekend free without too much downtime.

If I didn't have all that, I would be investing in an 8.8 and getting it setup and built.

Yeah if I could find a good deal on a 8.8 w/ LSD and 4.10 I would def. have it setup for the XJ... and then get my D30 setup with 4.10's.. got time though.. guess I'll keep my eyes peeled

[XJ Wheeler]

I know this won't help the OP. but wanted to post this link for the above two folks... WyoXJ this is more of a writeup for the Ch8.25, but will be the same process for your D35.. minus having to open up the center of the backing plate.. Hope this link helps you two on your decision to do this upgrade as well as completing it..

My brakes are getting old and i was going to get new drums, shoes, wheel cylinders, and hardware, but i think this swap would be a much better way to spend my money. I figure it probably wouldn't cost too much more to do this. Do you know if the donor zj has to be a specific year or have certain running gear?

Also, i didn't see a link.

[dagr8tim]

My brakes are getting old and i was going to get new drums, shoes, wheel cylinders, and hardware, but i think this swap would be a much better way to spend my money. I figure it probably wouldn't cost too much more to do this. Do you know if the donor zj has to be a specific year or have certain running gear?

Also, i didn't see a link.

I saw 3 ZJ (93 - 98 Grand Cherokee's) that were V8 with disks at the yard. I'd look for V8's and Limiteds & Larado's. I saw a 96, 98, and a 94.

[bluedragon436]

Lucky ass!! LOL.. I'm going to try and check out the only two yards we have here.. on Thursday.. if they got some goign to try and pick up all the needed parts for the conversion.. then I can replace all four discs and pads at the same time.. already got the front discs and pads waiting install

[dagr8tim]

Lucky ass!! LOL.. I'm going to try and check out the only two yards we have here.. on Thursday.. if they got some goign to try and pick up all the needed parts for the conversion.. then I can replace all four discs and pads at the same time.. already got the front discs and pads waiting install

Remember the bolt that holds the carrier pin in is 1/4" 12 point. I found that out at the yard and had to go back home and get the socket. I also found it easier to remove the one bearing cap to get easier access to the bolt.

[XJ Wheeler]

I saw 3 ZJ (93 - 98 Grand Cherokee's) that were V8 with disks at the yard. I'd look for V8's and Limiteds & Larado's. I saw a 96, 98, and a 94.

Thanks man.

[Crunchie]

I will be following this thread closely. I have all the donor parts and I am just waiting for a free second to do this to mine. Just too busy right now.:morningcoffee: It will be good to know what challenges to look out for before starting.

[dagr8tim]

I will be following this thread closely. I have all the donor parts and I am just waiting for a free second to do this to mine. Just too busy right now.:morningcoffee: It will be good to know what challenges to look out for before starting.


The biggest questions I still have is how to hook up the soft lines to the existing hard lines. Everything else is pretty self explanatory, and the only real other question is e break. But that can come from a number of sources.

I need to disassemble my backing plates and remove the old e brake shoes & hardware.

[Crunchie]

I will be getting assistance from someone who has done this a few time :woot:. Hopefully between the two of us we should have all our bases covered and be able to get it done quickly as long as we save this for after :buddy:. I will post a thread with some pics when we do it.

[dagr8tim]

I will be getting assistance from someone who has done this a few time :woot:. Hopefully between the two of us we should have all our bases covered and be able to get it done quickly as long as we save this for after :buddy:. I will post a thread with some pics when we do it.

For me, they are going on to a spare axle I have in the garage that I'm cleaning up. I can take my time and then swap the axle when I'm ready.

[Crunchie]

I have a buddy that had an 8.25 that I almost bought for that very reason. But then I thought... there is not a large resale market for the 8.25 up here so I should save my money and do it over the winter when my Jeep is parked. As long as there is no snow on the ground I will be ok... I am looking at an HP30 that I can re-build but there is no market for LP30's either so there is very little chance of recovering any cash after the swap.

[dagr8tim]

I have a buddy that had an 8.25 that I almost bought for that very reason. But then I thought... there is not a large resale market for the 8.25 up here so I should save my money and do it over the winter when my Jeep is parked. As long as there is no snow on the ground I will be ok... I am looking at an HP30 that I can re-build but there is no market for LP30's either so there is very little chance of recovering any cash after the swap.

My spare axle came with my parts Jeep. Anything I can use or sell gets scrapped.

[Crunchie]

My spare axle came with my parts Jeep. Anything I can use or sell gets scrapped.

I have stripped 3 XJ's in my driveway this year... :jumping0041: If I get another one I may have to live in it 'cuz my wife might kick me out.... :smiley-laughing021: Unfortunately they have all had the D35 out back and all the fronts were pre sold or damaged... I am looking at one ( wagoneer ) with a D44 out back and an HP30 up front but the guy wants WAY too much money for it. People up here think they are made of gold or something. :crazy:

[dagr8tim]

I have stripped 3 XJ's in my driveway this year... :jumping0041: If I get another one I may have to live in it 'cuz my wife might kick me out.... :smiley-laughing021: Unfortunately they have all had the D35 out back and all the fronts were pre sold or damaged... I am looking at one ( wagoneer ) with a D44 out back and an HP30 up front but the guy wants WAY too much money for it. People up here think they are made of gold or something. :crazy:

You see that everywhere. Too many people think they have something super rare and wanna get paid. I was looking at a set of 15x8 TJ Gamblers and the guy wanted $75 a rim for them. Granted I want a set (I have 3 now and would like to have them on my XJ & trailer with a matching spare), but not for that kind of scratch.

Heck, I found a set of15x8 TJ Ravines for $50 a rim in WV that were in better shape.

[Crunchie]

I have 2 sets of rims that I can't give away. I need cash for a winch and materials to build my bumpers but if no one is buying anything I guess I have to get creative.

[dagr8tim]

I have 2 sets of rims that I can't give away. I need cash for a winch and materials to build my bumpers but if no one is buying anything I guess I have to get creative.

If you were closer, I'd take a look. I want to get matching rims for the Jeep, spare, and trailer.

Right now the best I have is 8 steels with the flat pancake TJ center caps. I'd love to get some more Gamblers or another set of ZJ Canyons.

[Crunchie]

I have these
http://i1134.photobucket.com/albums/m608/crunchie72/P8230087.jpg
and these
http://i1134.photobucket.com/albums/m608/crunchie72/zjwheels.jpg

I am looking for $125.00 a set ... Just infor for anyone closer to me :D

[dagr8tim]

I am looking for $125.00 a set ... Just infor for anyone closer to me :D

I had a set of the first ones that I ended up losing in some wheeling and dealing. I'd love to get another set, but shipping would be more than the rims.

[4.3LXJ]

From what I have read this is a really easy upgrade, the only hard part is getting the emergency brakes hooked back up. I have read people use and not use the proportioning valve.

This is something I WILL be doing to my rig.

Going to be doong it here soon. Abovetimbedline will return afterhunting season for this upgrade.

[WyoXJ]

I got a '95 ZJ givin to me. It has ABS though will this still work for the swap? I want to swap the mc out also but did not know if it would work or not.

[Hartly]

if anyone did take pics of this swap or knew where to look id be very grateful.

[4.3LXJ]

Oh boy, old thread. If you are doing the ZJ discs from the ZJ D35 to the XJ D35 it is a bolt in all the way. On the XJ D44 IIRC he said you had to bore (read use a die grinder) the backing plate a little to make the center hole a little bigger. If you use the Cryco 8.25 use the Liberty rear discs. Msmooreberg has done this upgrade to his XJ

[Hartly]

I have the 8.25. Libby stuff should just bolt up right?

[XJ Wheeler]

Zj does too, just have to open up the hole like Steve said. E-brake is better to get the liberty. I've found the zj parts to be cheaper and easier to find, that's why i chose to do it that way. I haven't gotten to put it together though, i still have some parts to get and need time.

Sent via messenger pigeon - i talk, he types.

[Hartly]

thank you both for your information. i too will soon be in need of rear brakes and figured id upgrade while im at it

[XJ Wheeler]

thank you both for your information. i too will soon be in need of rear brakes and figured id upgrade while im at it

That's why i'm doing it too. lol. Its a good mod, especially if you find an axle with all good parts already. The axle i picked pretty much needed everything.

Sent via messenger pigeon - i talk, he types.

[Hartly]

Does anyone know the name of the bracket that mounts the caliper bracket n such to the axle? Does it have a proper name?

[Brasscatz]

Are you talking about the knuckle?

Sent from my Samsung Galaxy S4 because my microwave couldn't do it

[Hartly]

But in the rear.

[NW99XJ]

That would be the backing plate I believe.

[Hartly]

The problem im encountering is that both the bracket and the sheet metal dust cover seem to be called the backing plate

[XjJeepacorn]

I've always refered to them as mounting brackets. I think thats as technical as it gets. Breaks were the first thing I learnd at my old shop and the boss handed me the bracket and just said clean the bracket up on the wire wheel lol! I did this swap last year and I'll tell ya my jeep has never stopped so good ever!

[dagr8tim]

I've always refered to them as mounting brackets. I think thats as technical as it gets. Breaks were the first thing I learnd at my old shop and the boss handed me the bracket and just said clean the bracket up on the wire wheel lol! I did this swap last year and I'll tell ya my jeep has never stopped so good ever!

I assumed they were just part of the backing plate. I got the plates and brackets as a unit.

[XjJeepacorn]

I got mine at the junk yard during a free parts day event 50 all you can carry :)

[XjJeepacorn]

This was one of my first write up ever written so if you have any questions or feel I've left something out let me know

http://www.jeepacornforum.com/viewtopic.php?f=28&t=98