D44 disc brakes conversion

dave92cherokee said:
What about the Grands that have the 44 in the back. Granted it's the aluminum version that we don't want the entire axle from or any big parts, but did they come with rear discs too? Might be an easy option for going to the dealer or finding a site online that has the factory pieces for it and then it would be a bolt on install.
Click to expand...

ZJ D44a have the same axle flange as the ZJ D35 so the disc brakes are exactly the same. Your local Pull-A-Part or similar junkyard should have a ZJ sitting there that you can pick parts from. When I got mine from the ZJ with the D44a in it, there were 3 other ZJs there with disc brakes on them waiting for someone to pull parts from. I paid $50 for the Caliper brackets, backing plates with full e-brake hardware, calipers, and rotors and pads! Normally I wouldn't have grabbed the rotors and pads but they looked brand new as if the rear brakes were done literally days before the Jeep was junked. Point is the Junk yards will have everything you need just need to have the skills to make it adapt which honestly isn't that hard.
 
So i am in the middle of doing this mod on an XJ Dana44 after locking up my drums on a snow run and breaking my center shaft on my carrier. I have ZJ disks. I elected not to drill the caliper bracket, backing plate and TJ retainer plate but am going to modify the axle flange instead. My reasoning is that I do not plan to return to drums at any point and it is the least modification. Have researched this a lot and in some ways for the DANA 44 perhaps the best mod is the Crown Victoria in terms of amount of fabrication necessary but i found the ZJ parts and went that route and I think they may work best for me.

Have not decided whether or not to remove the axle to drill the flange and have also not decided whether or not to weld up the holes or just make new ones. I have read that you can line up one hole with a TJ rubicon spacer and drill the others pretty easily. Some people weld up the holes which then makes drilling difficult, others put steel plugs in and then weld up from the back. Will report on what I end up doing but I have pulled the trigger and have pressed on the bearings with undrilled TJ retainer plates so i am committed to drilling the flange and not the caliper bracket. I

Some people report premature seal failure after doing this mode and the theories range from the rubicon retainer's built in spacer being to deep to using Timken seals and not NAPA ones. My hope here is that this issue is caused by damaged shafts but we shall see. I will be checking clearances as I do this.

Unfortunately there is not a huge amount of info on doing this mod on an XJ Dana 44 and the fact that it's bolt pattern is unique makes it more challenging.

But hey Jeeps are built not bought right? More to come.

Current activity:

ZJ caliper brackets backing plates, proportioning valve and old core calipers obtained from Pick and Pull
New rotors, calipers, ebrake shoes and hardware obtained.
Caliper bracket and plate enlarged with HF sanding drum on drill to 3"
TJ Rubicon plates and Timken bearings pressed on to AlloyUSA chromealloys (do not know yet if I will need new wheel studs)
OX locker out with carrier center shaft replaced and reassembled.
Crown Ebrake cables that will work with the ZJ purchased
TJ Rubicon brakelines purchased.
 
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that was what i was thinking about just modify the axle flange, everything else seems to be as simple as bolt it on then. as far as the spacer issue i was looking at fabricating a space not as a single part but to make it like a hat bushing then boring my retaining plate to have a press fit, TIG the two together and i then have a one piece with the original plate. that and fill welding the plate to make the lugs all match the D35 zj brackets. with the brackets being cast steel it is very difficult to have a quality weld on cast (yes it can be done, but it isnt worht the effort) just an idea. if you want nick PM me i am a Machinist with access to equipment to weld and machine the parts, we can bounce ideas off eachother and see what works. i currently have a d44 out of an 87 i am doing the zj swap and abs on... i could use some othe points of view on the subject.
 
So am nearly done with this. Lessons learned below. I did take pics and will put together a writeup when I have some time.

Again this is converting an XJ Dana 44 to ZJ brakes.

1: You can drill the axle flanges. You can drill fairly easily with a good drill. It is not going to be perfect. I ended up drilling 3 new holes, one slightly enlarged and 1 essentially a notch. Used grade 8 hardware and threadlock. I figure it is not perfect but the weight of the vehicle is not actually on that flange so I am going to be fine with it. I carefully tested the TJ rubicon retainers. They do not see to squash the oil seal and the clearance seems just fine.

2: Crown ebrake cables are perfect and probably the easiest part of the mod.

3: Keep the ZJ flexible hoses to the caliper they will bolt up directly to the XJ hardlines and it is pretty simple to modify the mounting brackets to attach to the top of the ubolt plate.
The hard lines from a TJ Rubicon will not fit and if you buy them you will have to return them like I did. The XJ axle is not much like the TJ one externally


4: Replaced my proportioning valve with one out of a Disk brake ZJ. Comparing various ones I have acquired I think the valve for the drum brake ZJ is exactly the same as the XJ. You need to find one out of a ZJ with rear disk brakes. This pic on this page sums it up pretty well. I changed the whole valve but I could not see any internal differences. Probably just fine to go grab the internals from a junkyard and swap them over.

http://www.jeepforum.com/forum/f11/rear-discs-438001/index2.html

The ZJ mechanism for the ebrake basically sucks but that is because I am sick of drum brakes. When you grab stuff from the yard make sure you get the ebrake levers and when they fall apart this is how you put them back together. They defy logic.

http://www.jeepforum.com/forum/f13/need-help-reassembling-rear-disc-brake-drum-307658/

Anyway I still have to bleed the brakes and drive for a bit. Will report back.
 
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What model was the brake cables xj d35? Of zj? I would think xj because the zj runs cables centerline where the xj (at least my 99) runs it down driverside "frame rail" just want to make sure I get you right here.
 
nickguy said:
and 1 essentially a notch.
Click to expand...

This would concern me some. Post up some pics when you have time. I haven't started the swap, I'll let you be my guinea pig. ;)

I do have the crown vic discs and I'm not entirely happy with them as I've said. Would the ABS "booster" under the hood have any effect on the rear brakes even though the ABS doesn't work? Should I take all that out and run new lines from the MC to the proportioning valve?
 
So at some point we should request a move of this thread into tech.


My pics are here. They should be self-explanatory. I am prepared to catch major flak for my decisions on where I drillied the flange. I elected to keep the hole at 4:00 oclock but had to dremel it out a bit to make sure it exactly lined up with the axle. I then used the plate as a jig to drill the other holes. The hole/notch at 11:00 oclock is problematic but I sacrifice there to maintain the integrity of the holes at 4,10 and 2. I considered the idea of putting a weld on the notch but I think I am fine with leaving it alone and revisiting regularly to make sure it all holds. I would hazard a guess that the reports of premature seal failure have a lot to do with not getting the backplate perfectly aligned. Think it is totally possible to position the holes better than I did but I think there are going to be tradeoffs whatever is done.

http://www.dropbox.com/gallery/24124260/1/diskbrakes?h=8aca6f
 
Joshooha said:
This is like a 5 min video kind of explaining a little bit.
http://youtu.be/WbxBW1PzrRo
Click to expand...

I actually saw this video and commented on it (the only comment on it) and you were mistaken on what you believed to be the Proportioning Valve. What you were calling the prop valve is actually called a distribution block that does not contain a valve in it. It simply splits the brake fluid to two lines from the one coming from the proportioning valve up front under the hood. The Proportioning valve is the aluminum block that is mounted near the master cylinder that has one line from the master cylinder running into and 3 lines coming out of it, two going to the front two wheels and one going to the back. Some don't switch the prop valves out and some do. Some report braking improvement without switching the valves and some report no improvement to even braking being worse until they change out the valve. So really each has a different experience but the recommendation for doing this modification is to grab the prop valve from the grand cherokee to ensure you have all the necessary parts to make this work right.
 
agreed on proportioning valve. A huge lesson learned for me on this is make sure you mount the calipers the right way up. I bought new ones and ended up with two passenger side calipers. Wagner boxed a pass side caliper in a drivers side box. I figured i would try and make it work. The bleed valve has to be higher than the flexible hose mounting. Take it from me, it is impossible to get the air out of the system completely. The calipers will mount either side but if the bleed valve is lower you are going to get a spongy pedal. Bled right up with the right caliper.
 
nickguy said:
agreed on proportioning valve. A huge lesson learned for me on this is make sure you mount the calipers the right way up. I bought new ones and ended up with two passenger side calipers. Wagner boxed a pass side caliper in a drivers side box. I figured i would try and make it work. The bleed valve has to be higher than the flexible hose mounting. Take it from me, it is impossible to get the air out of the system completely. The calipers will mount either side but if the bleed valve is lower you are going to get a spongy pedal. Bled right up with the right caliper.
Click to expand...

I think this is alot of my problem, the pasenger side caliper is upside down, meaning the bleeder is at the bottom. I have bled this caliper with it off and right side up but I still don't really like the way it sits. With my axle being an XJ 44, could I turn the backing plate a full 180* and mount the caliper forward instead of rearward? Any reasons I couldn't or shouldn't?

Also, if anyone knows about the ABS booster under the hood, if that should come out or not. I can make my own replacement lines, I'm just curious if I need to take all that out.

Thanks.
 
High2by said:
I think this is alot of my problem, the pasenger side caliper is upside down, meaning the bleeder is at the bottom. I have bled this caliper with it off and right side up but I still don't really like the way it sits. With my axle being an XJ 44, could I turn the backing plate a full 180* and mount the caliper forward instead of rearward? Any reasons I couldn't or shouldn't?

Also, if anyone knows about the ABS booster under the hood, if that should come out or not. I can make my own replacement lines, I'm just curious if I need to take all that out.

Thanks.
Click to expand...

Or just get the correct caliper....
 
It is the correct caliper in that it came off the same crown vic, the issue is the way it is mounted. I need to see if I can rotate the mounting bracket and mount the caliper in front of the axle instead of behind it. I just don't know if that is possible. I guess I just need to try it and see if it will work.
 
I am in the process of doing the crown vic swap, it seems the the right and left caliper and bracket are identical and I think, wouldn't swear that one caliper was leading and the other trailing on the vic, so I wouldn't see a problem doing the same on the xj, I'll take a look next time at at picknpull.
 
Yep. That's it but on my XJ, both calipers are mounted behind the axle which put the passenger side upside down. I didn't do the install on it so I'm not sure why it was done this way. Maybe it HAS to be this way but if not then the passenger side should go in front of the axle. At least I'm gonna try this and see if it works.
 
You know I guess, and I did not try this but you could temporarily bleed the caliper with it just placed upside down, (so that the bleed valve is higher) on the rotor so that you do not force the pistons out and then mount it the right way up. The other possibility would be just to get 2 ds calipers and mount the passenger side upside down so that the bleed valve would be up??? :-)

My head hurts.
 
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