XJ Rear disc swap with pics!

[98xjjeep]

Just finished swapping rear discs into my cherokee. I can now stop on a dime! Best $100 I have ever spent. I got the backing plate, caliper mounts, and calipers from a grand cherokee in the junkyard. My guess is a '95. I then bought new rotors and parking brake pads from advance auto.

Junkyard parts- $20
Rotors, pads -$76
Total so far- $96

Heres the Junkyard parts cleaned up and stripped down...

First thing I did was remove the axle shafts which meant removing the C clips...

Once I pulled the shafts I started removing the old brakes...

 

[98xjjeep]

Next was enlarging the new mounts and backing plate to fit. It doesn't take much at all...

I then put the new mount and backing plate in place...

Then I assembled the new brakes...

And your done! Just hook the soft line out of the caliper to the hard line, which you have to bend to make for a good fit. The only thing else to do is hook up the parking brake cable which I will do tomorrow.

 

[8379qtj10]

How did you modify the brake system to work from drums to disc on the rear??

 

[98xjjeep]

How did you modify the brake system to work from drums to disc on the rear??

Don't have to do anything. Just bend the hard line up so the soft line from the caliper can hook up to it.

 

[8379qtj10]

Great write up but I though drum systems held a little pressure on the rear wheel cylinders.
Proportioning Valve I think has something to do with a Disc/Drum or Disc/Disc system.

 

[98xjjeep]

From what i understand the disc/drum setup sends more fluid to the rear then a disc/disc. So far the don't seem like they will lock up on me. I drove it in the rain with hard braking. Of course if I can get them all to lock up if i try but I don't think it will be a problem. The reason for doing this was, driving everyday and when im on a steep slope wheeling and have to back up, the front brakes would lock up since the rears don't work and it would be sketchy, Having enough pressure in the rears means when im braking while backing down a slope, it will stop since all the weight is on the rear. Some guys like the change the prop. valve out with a ZJ one so I my switch and see what both are like but right now I couldn't be happier.

 

[8379qtj10]

Thanks, I love low buck upgrades
Might look for some stuff at the pull a part Saturday

 

[HaPtOAD]

This works for a 44 out of a XJ or MJ also. A little more work though.

 

[J.C.]

Good tech and pics, thanks for the write up.

 

[98xjjeep]

Good tech and pics, thanks for the write up.

Thanks!

 

[TJcrawler97]

Nice work.

 

[Archdukeferdinand]

So far the don't seem like they will lock up on me..

Doubt they will, I dd'd mine on 33s for over a year with ZJ discs, one of the best upgrades I ever made. For me the biggest advantage is actually modulation in snow and loose stuff. You can put the brakes on way more liberally without locking them up and bringing the ass-end around.


As for fluid volume front/rear, that may be to account for the long brake lines.

From what I understand disc brakes run at about 3x the pressure that drums do, and simply comparing the size of a wheel cylinder to a brake caliper will tell you which will hold more fluid.

I never ended up wanting a prop valve.

GREAT writeup, by the way. Good pics and tech.

PS- Did you think about replacing the studs on the axle flange with some longer ones? Mine looked like yours with the threads countersunk in the nut but I just locktited the shit out of them and did a buttload of testing on private property before calling it adequate. It always sort of nagged at me though.

 

[chris]

Great job dude! I was thinking about doing the ZJ conversion as well, but decided to go the 8.8 route instead. Now all I gotta do is find some more cash to buy the rest of the parts to do the swap.

 

[98xjjeep]

GREAT writeup, by the way. Good pics and tech.
PS- Did you think about replacing the studs on the axle flange with some longer ones? Mine looked like yours with the threads countersunk in the nut but I just locktited the shit out of them and did a buttload of testing on private property before calling it adequate. It always sort of nagged at me though.

Thanks. I thought about the studs but they seem to have enough thread engagement to be fine. I may change them down the road if i take it apart again for some reason. I covered it in locktite also.

Great job dude! I was thinking about doing the ZJ conversion as well, but decided to go the 8.8 route instead. Now all I gotta do is find some more cash to buy the rest of the parts to do the swap.

Yeah I was thinking of going with a 8.8 with discs but felt like the 29sline 8.25 will be fine on 33s. Your running a dana 35 locked right? yeah its about time you change that out for something beefier.

 

[chris]

Yeah I was thinking of going with a 8.8 with discs but felt like the 29sline 8.25 will be fine on 33s. Your running a dana 35 locked right? yeah its about time you change that out for something beefier.

Yep! I'm beating the snot out of the D35 too and it hasn't broke yet. Probably because I'm still running stock gears. I managed to twist the drive shaft before the rear end broke. I'll be running 456s after the swap. Part of me wants to wheel the D35 till it breaks, but I want to go higher so the D35 has to go.

 

[Andy J.]

Nice write up! Good pics too!

Yep! I'm beating the snot out of the D35 too and it hasn't broke yet. Probably because I'm still running stock gears. I managed to twist the drive shaft before the rear end broke. I'll be running 456s after the swap. Part of me wants to wheel the D35 till it breaks, but I want to go higher so the D35 has to go.

If you keep that D35, I would suggest trussing it. I wheeled the D35 in my YJ with 33s and the axle seals ate 1/4" deep grooves into the shafts because of housing flex.

 

[jds97Wrangler]

Gears will not be as hard the D35 as what size tire you're running, I don't know what size tire you are runing, but if you go bigger then 33 I would highly recomend throwing the d35 in he dumpster and putting something stronger in.

I ran 32's on my TJ for a year never had a problem then the following year I went wth 35x12.50's and the first weekend out I exploded the spider gears in the D35. I replaced the D35 with a 8.8 and did not have any more issues I wheeled it for year before I sold it.

 

[chris]

I shouldn't have spoke about the D35. Guess what broke at DPG today? heheh I finally snapped a shaft! The D35 will be coming out and the 8.8 will be going in soon. I'll be selling the D35 with locker and spare shafts soon.

 

[mbost]

I shouldn't have spoke about the D35. Guess what broke at DPG today? heheh I finally snapped a shaft! The D35 will be coming out and the 8.8 will be going in soon. I'll be selling the D35 with locker and spare shafts soon.

We can fix it, and you can beat the snot out of it a little harder with the 8.8. The 35 had all it could handle Bdoz, it was def. impressive today!