s346k

just want to share and open this up to questions/comments. as the title states, I completed the zj rear disc swap today. a friend who had already done the swap on one of his xjs helped me out, so things went fairly smooth.


we got the parts from a 96 grand Cherokee at a local junkyard. as aforementioned, it is almost a direct swap. I say almost because I have an 8.25 axle and the parking brake issue. i enlarged the backing plate where it goes over the hub and ziptied the (now) dead parking brake cables underneath the jeep. my parking brake didn't work before, so it was no big loss...not to mention I don't recall ever using one in a vehicle with an automatic transmission. I used a metal shaping bit for my drill to enlarge the holes in the plates. it wasn't terrible, but I felt it would've been quicker than using my dremel tool. I removed the dust shields prior to any work on the plates.


initial thoughts: dang. it has a stiffer pedal and the braking abilities are much better. although I'm fairly certain my back brakes weren't functioning beforehand.


observations: longer studs for the backing plate are questionable. I felt comfortable with reusing the stock ones. after getting everything seated, the nuts were flush with the end of the stud. I feel comfortable with that result, so I left it alone. there was quite a bit of rust and grime buildup on both my hubs and the plates. I spent a good bit of time removing said gom from both of the surfaces. I feel this was time well spent. in conjunction with the use of trial and error on hub fitment, the plate was as good as it could get both depth and center. I am also not sure that a proportioning valve is necessary. surprisingly, my xj was very cooperative with disassembly and reassembly both.


if I had to do it over again I would check to see if the bleeders on the calipers were going to cooperate prior to installation. I ended up fubaring one of mine and had to bleed that caliper at the line. not the best method by far, but I had to get this thing together and had no choice. also, given the time of year and cold weather we've had...I would preheat the gear oil going back into the dif. I used what had been in the garage all winter. despite the fact it is 75-90 synthetic oil, it did not want to move.


all in all it wasn't terribly difficult and quite rewarding. i will suggest this to anyone looking for a cheap brake upgrade. however - something I found odd. I bought new Timken wheel seals. they were too big for my hub. I am positive I have a 8.25" axle. part number 8835s. I called the store and verified the part number. they are supposed to fit, but did not. I cannot recall the number on the seal itself, but it had a red ring and both of them were the same. I had plans of changing the seals, but did not because of this. the old ones did not leak and were not damaged, and again - because I had to get it together - I reused them. anyone else encounter this?

EZEARL

This?

https://www.cherokeeforum.com/f2/wha...d-help-189424/

s346k

it's an 8.25. it's also a 97 model year. I suppose I could've counted splines when I had the axles out, but I thought the seal is the same. beats me.

EZEARL

According to Quadratec all 8.25's from '91 to '01 take the same seal.
Rear Axle Oil Seal

For 91-01 Jeep® Cherokee XJ with Chrysler 8.25" Rear Axle

Quadratec Part No: 52420.23
Manufacturer Part No: 4137426

salad

Glad you joind the legion of 4 wheel discs! 8835S is what I used on my '98 C8.25. Fit like a glove!

s346k

I thought I'd update after a week's worth of driving. gotta say - love the newfound braking capability. miles ahead of the drums. however, I must make note of something:


clunks. I hate clunks. I spent a fair amount of time ridding my jeep of them. well now I have a new one. pretty much any time the rear axle is shifted any direction, for any reason, it clunks. low speed turns, bumpy roads, high speed turns, places that look bumpy, but really aren't, cloud cover, too much sunlight, etc. ugh. I suppose it's a worthwhile trade, but damn, I had a nice, quiet xj.


I assume the disc brake setup is letting the axle shift, causing a clunk as the rotors etc move and bump into the brackets. this isn't a huge deal to me. if something detrimental occurs, then I will look into it further.

PocketsEmpty

You might want to take your wheels off and check your bolts. I've been running my ZJ discs for almost a year and have no clunks. Just some squeaking, probably because I was lazy with disc brake grease.

Did you get your E-brake working?

s346k

no on the ebrake, nor am I worried about it. I double checked all of the fasteners, I highly doubt anything is loose. I made a 400 mile round trip to central ohio hours after completing the swap, I'd like to think any issues would've already reared their ugly head(s).


I consulted my friend (owned multiple xjs, 12+, and has done the swap) about the clunking. he said some do it and some don't. he apparently put 30k+ miles on his clunking disc swap, so whatever. we'll see. if you see a thread where my **** blew up then we'll know haha.

ksrummel

Is there a complete write up on this with pics?

s346k

multiple.

EvstaG

Im looking at doing this swap too, and am just wondering if anyone has a solution to the elusive parking brake cable issue. With the manual transmission, I would like to have it functioning. Most of the the swap write-ups I recall just say that the e-brake cables work with "some modifications."

rav

here you go:
https://www.cherokeeforum.com/f51/re...-8-25-a-57807/

salad

For mine I grabbed the smallest U bolt kits from Home Depot (near the chain section) and just clamped the end of my existing cables onto the lever that actuates the shoes. I need to adjust them again but certainly works!

EvstaG

Nice, that sounds like not a bad idea. Havent looked close enough at thw ZJ brakes yet, did you lose any cable length with that, positioning wise? My new cables get fairly close to taught already.

salad

Gained, actually. That's why I need to adjust lol. On the XJ drums the parking brake cable goes in at the bottom, in ZJ land it hooks in at the top. Probably an inch or so. Slack doesn't seem like anything the equalizer couldn't take care of. Right now the e-brake won't hold the Jeep on much of an incline but it does engage.