First off I know that this may seem like a simple issue. Also, I have swapped these axles in a pile of YJ's, TJ's and CJ, and everything else. The swap and all it entails is not the problem. On most TJ conversions it seems to me that the stock brake system on the vehicle worked well with the Explorer rear disc calipers. A couple of the Tj's needed additional modification to get the desired braking dialed in. No Problem.
The problem I'm having is that after swapping an 8.8 into the rear of my own XJ (a hand me down from pop's), I'm not happy with the rear brakes at all.
The jeep has a 6.5" lift, 4.56 gears, 35" KM2's. Pedal feels good in the cab. Brakes have been bleed to the maximum. Seems like I'm just getting front brakes. The rears work..... but not like they should. Truthfully, I wanted to put a drum brake rear in so that I didnt have to modify the rest of the brake system to have a properly dialed in rear disc set up. Then i came across a disc rear and said screw it... So I put it in.

I know alot of guys will say that "mine stops great!". I see jeeps like that everyday, and when I drive them I feel like the owners version of great and my version differ greatly. Some real world input would be appreciated and very helpfull.

If I dont get a resolution to "sweet" braking I'm gonna swap some ranger FX4 drum brakes on it and call it a day. I know drums dont sound sexy buit I maintain my vehicle. I feel like a properly maintained and adjusted drum set up could work well for my usage and driving.

I also have read almost every 8.8 swap write up since the internet started.... Looking for long term real world brake info for XJ's with 8.8's. Drum or disc....

Thanks in advance for any help ya'll might have

Got the nipples up?

Did the swop on my xj and it brakes great

Got the nipples up?


X2

I have made that mistake before.

proportioning valve??????

Thanks for the quick replies guys. I took the calipers off and bled them with the bleeders at the highest point and a block of wood for the piston to clamp up on while bleeding. I was gonna do a prop valve swap as I have about 10 here at the house. Disc/drum, Disc/disc, new oe, and aftermarket.... I had intended on swapping the master and prop valve. Before I did so I wanted some feedback from other owners... Just to keep me from running in the wrong direction. I jacked up the rear, secured the jeep on jackstands, put it into gear...... apply the brakes and they will barely stop the rear wheels. Only if I mash the shit out of the brakes will they stop.

The way the calipers and brakes feel, it reminds me of a QTU Quick Yake Up caliper.

I also didnt want to change anything right away because I anticipated that some people who had done the same swap on xj's were not having this issue. Makes me think I need to look for some other issues potentially...

for the guys who have done the swap, does you brake pedal feel firm with out excessive travel?

(Quick Take Up caliper)

honestly it was better then before.

i didn't change anything, just unhooked the line and hooked it into the new axle.

you might try doing a proper vac bleed job instead of the standard peddle pushing method if that is what you are doing.

So you went from rear drums to rear discs and didn't change the valving? :shaking: Drums don't use as much line pressure as discs do so of course they're gonna work like crap...

Not quite apples to apples, but I like turtles!

I did the 8.8 swap into my '96 2wd (at the time) Sonoma with 31's. The Sonoma used to have a drum brake GM 7.625" 10-bolt and I was very displeased with the discs at first. I had the rotors turned that I got on the junkyard axle and cleaned up the calipers. The counter jockey at Oriely's talked me into kick ass ceramic pads and all that jazz, but after ditching the proportioning valve completely, replacing the rotors with new ones and getting cheap semi-metallic pads the 8.8 Explorer brakes came alive. I can't say what specifically made the difference, but I liked it.

Try an adjustable P-valve. Make sure the caliper pistons aren't sticking somehow or replace the calipers all together (loaded calipers are only $43/side with core at Napa). Lube up any and all slide pins/brackets and try a set of cheap ass semi-metallic pads if you haven't already.


What's this info about the FX4 8.8" brakes? I'm interested just for the sake of knowing. I know the newer Ranger 8.8" axles have pretty decent brakes in the FX4's, but didn't know they were a match for the Explorer 8.8".

I mean... Nothing with oversized tires is gonna stop like a BMW, so stopping "great" prob isn't a good way to put it. Mine stopped fine, but not great with 37s.

The calipers are new and all the guide pins are lubed with a graphite dry film lubricant so that they dont even try to attract dirt/ grit. I have an adjustable wilwood prop valve sitting in the garage. I usually match up a master cylinder toa prop valve and get the set up that most likely will jive with the chosen calipers.

I know that the jeep wont stop like a BMW. But truthfully, with the fronts doing most of the work on the set up I have now, most people drive it and think it stops great. I drive it, and I'm not happy with it. I know If I get the 8.8 brakes operating right that I will have some awesome braking. Once again not BMW'ish, but I think ya'll know what I'm looking for.

The FX4 Rangers had bigger Drum brakes than standard rangers. They had a 31 spline 8.8..... I just thought about swapping over to the FX4 drum set up and calling it a day. I know my disc/ drum master cyl and prop valve would be happy working with the drum set up from the ranger and probably maintain a stock feeling pedal.

Postaldave - "honestly it was better then before.i didn't change anything, just unhooked the line and hooked it into the new axle.you might try doing a proper vac bleed job instead of the standard peddle pushing method if that is what you are doing. "

That is kinda why I put this thread out.... To touch base with other folks and check their real results. I have had similar result on any other 8.8 I put in any jeep before. Installed the axle, plumbed some hard lines to the caliper flex lines, new pads, good rotors, thorough bleed job and then a road test..... the braking always felt better than the stock drum set up. Even without a MC and prop valve change. My junk just has to give me a hard time.....

Looking back on the swaps done before. Most guys that hated the drum set ups would have probably been in good shape had they ever adjusted them properly. (Well, except any model 35 with drums. that whole axle is a bad decision from jump street).

for my driving I think the FX4 brakes would do me right. I know it doesn't sound as sexy as "a ford 8.8 with disc brakes conversion". but if it gets it done without alot of hassle, i'm good with it.

I used to build alot of wide track axles for CJ's. I would take the bigger old style 11" drums off the earlier narrow track rear axles and install them on the wide track rear axles for whoever I was building the axle for. Properly adjusted, the guys were always very happy with the "upgrade" and that they still maintained their part brake feature. Other axles that I did the disc swaps on sometimes left me feeling that "yeah, we put some cool expensive stuff on here. but IMO it leaves alot ot be desired". So even though it seems like I'm going backwards by possibly putting the drums on, it might be just what the doctor ordered.

Thanks again for the replys.
__________________

I have an adjustable wilwood prop valve sitting in the garage.

Why not use this instead of buying more parts? Your problem is the valving. Wrong valve = shit brakes... Brake swap 101...

Why not use this instead of buying more parts? Your problem is the valving. Wrong valve = shit brakes... Brake swap 101...

multiple peole have told you this ^^^ you know the answer now quit bringing this fuckin retarded ass topic up unless your gunna put some real tech in it..

Yeah man......

thanks for the input. How many xj's or tj's have you seen with an 8.8 swap and discs with no other mods? I have seen plenty. I know that the Brake 101 bible would say that you need to change the prop valve to match the caliper. I'm saying that it doesnt seem necessary on every one of these swaps. Again, thanks for the input. Specifically, I was putting out a feeler to see what results other guys were getting with their stock plumbing/ 8.8disc's. If they changed any parts, how did the change improve or decrease their XJ's braking. I'm not trying to have a class on how brakes work.

FWIW....I did the 8.8 swap with stock disks in my 94 XJ. Actually pulled it out of my YJ and put it in the XJ. I ran that 8.8 for a total of 6 years over the 2 rigs and never had one single braking issue. It stopped a billion times better in both rigs over stock.

No mods to master, booster or valve.

Seems most year XJ proportioning valves are actually a pretty good match for the explorer caliper. The surface area for the explorer piston is slightly larger than the combined area of the stock wheel cylinder surface area so the net result is a pedal that travels just a tad further, however the force exerted is larger.

Thanks for the input once more. Muddypaws, it was feed back like yours that had me want to ask around and see if my situation was mine alone or if there were others who were/werent pleased with the "upgrade". As I had said before, I had done this swap SOOO many times and never had this happen on the other vehicles. So here is where Im at with it now. I rebleed the brakes just for good measure.... OP's checked the brakes, they stopped, not nearly like they should. For the sake of trying something different I did the prop valve/ piston o-ring removal mod. Took all of five minutes. Rebled the system and the prop valve itself. Massive difference!!! I would call it very nice braking effort. The pedal after the mod was still firm but with very little effort to stop even a rapid stop from 55mph. The pedal in the cab has about the same amount of travel as it did stock. If the travel is different, it's so minor that it's not measurable. I have heard that under heavy braking on a slick or wet surface that the rears might want to lock up. I gave that a try too. and as of this time I haven't had that experience.

For my own reference, what year is yours. I want to compare the brake specs for years I know work well with no mods to your year brake specs. And is yours ABS or not.

Mine is a 1995 Cherokee Country addition with HD towning package etc. What you are asking to do runs right along with my curiosities about the swap I did on mine. The part number for my master cyl and a Grand with disc brakes are the same. Piston and stroke are the same so from the outset I knew that a master swap wouldnt be required. I towed around 3200 lbs tonight and braking felt by far improved. That was on a trailer with no electric brakes so the total braking effort was coming from my xj. It did well. I love a disc swap on anything but pedal feel, pedal travel, and brake bias are important items that I like to keep near stock as possible. If you come up with some quirky info please let me know. I will do the same.

I put JK 44s front and rear in my CJ and used the stock master and prop valve and ran new lines to the JK disc front and rear. Everything works well and all I did was remove the "plunger" from the inside of the prop valve. I don't know the right term for it but it is the little rubber plug that is spring loaded in the rear of the prop valve. It helps keep constant pressure on the rear drums but will not work with discs. If you have a few prop valves laying around maybe try doing the same and see if you get the same result.

I did exactly that same mod. Not sure of the term for the part but it has been working great. I just call it the prop valve piston o ring. whatever.... it worked. that was the part I said I removed (earlier post).

97 XJ with 8.8 swap. I removed the plunger and spring in the proportioning valve. Now there's *slightly* more bias to the rear. The only time the rear locks up first is when I quickly jam on the brakes in loose or slippery conditions. I have a Tilton adjustable prop valve I've been meaning to install, but really haven't had the need.

EDIT: now that wasn't very nice......

A ZJ proportioning valve bolts up and was designed for front/rear discs.