New to me 1998 2wd, 4.0, Auto
Ive got all new brake hardware. Except for the proportioning valve and the hard lines, from the master cylinder to the rear wheel cylinders is all new. The Jeep stops well, but the amount of pedal pressure required is a lot more than any modern car I have driven. If that’s how these Jeeps normally feel then that’s fine. But, I just want to be sure I haven’t missed anything. The pedal feels almost like manual brakes on an old Camaro I had once, though I can feel the booster is working. My 2001 Silverado requires hardly any pedal pressure in comparison. What do you guys say?

 

A lot of it is relative. Many new cars have very overboosted braking systems, IMO. The real question is how does it feel compared to my '98, for example, and that is a hard one to answer over the internet.

 

Yeah, that’s just how these older XJs feel they’ve got a heavy pedal compared to modern rides. If the booster’s working (you can hear it hiss when engine’s off) and it stops straight, you’re good. No leaks, right? Some guys swap in a dual-diaphragm booster from a WJ Grand Cherokee for a softer pedal, but honestly, you’ll get used to it. Just Jeep things.

 

Hold on. I can get a softer pedal with a WJ booster?

 

I don't think the WJ booster is an upgrade for later-model XJ's. That's a common swap for earlier models with single diaphragm boosters.

Stock sized tires, or larger?

Is your vacuum system operating properly (does your AC vent selector work properly)?

Is the pedal firm (i.e. no air in the system that would require more bleeding)?

Did you replace the soft brake lines?

 

Yes to all those questions. I'm running 30" tires. After I read your post I did a lot of reading about brake upgrades and discovered there isn't much that can be done to this '98 while still running 15 inch alloy wheels. It's fine. I'm just trying to love this Jeep and make it as enjoyable as possible. Also, I've never owned one before and don't have anything to compare it to.

 

What kind of brake pads are you running? I find the ones made for high performance tend to give a much better pedal feel and brake response, particularly when they get hot.

 

I got a rotor and pad kit from Rock Auto. Ceramic pads and the brand name is "Quality-Built". Of all the choices they were about middle of the pack in pricing

What is the recommended pad? I'll swap them out if there's a much better option.

 

I run Hawk LTS pads in the front. They're more expensive than your average parts-store pads, but they've got way more friction and handle heat very well. IIRC, they use a similar compound to the HPS pad, which is popular for street cars.

 

Black Magic brake pads are a significant upgrade in stopping power. They produce a lot of brake dust though. I really like them.

https://blackmagicbrakes.com/

 

I've had a couple Jeeps with really hard brake peddle (pushing). But to me, when I was pushing hard with little results was a bad booster and/or actually the seal that was sucking in brake fluid from the back of the master cylinder.
The past 4 Cherokee's have all been good 'brakers' except my son's 01 with 34's. His was kinda scary to have a quick stop.
Have you ever tried reverse bleeding? It sounds to me that you need another couple bleedings. Starting with the Master to bench bleed. While it's off, try and look down in the booster for brake fluid in the bottom. Or use coat hanger with a
piece of rag zip tied to it and see if any comes back wet.
Currently, my other 3 Cherokee's and one MJ was VERY GOOD in braking, and would lock them up if pushed it that far..
I've used empty baby food jars by punching a 1/4" hole in the tops and force in some clear nylon tube that fits the bleeder nipple and then about 1/4 fluid in jar to keep air from being sucked back in.
And then about 8-10 slow but firm pumps, making sure peddle goes to the floor. It helps with 4 jack stands holding the vehicle up with all tires off.
And almost forgot; if the fluid coming out is dark, suck out reservoir and clean it out. THEN fill with fresh. (don't mix synthetic and regular) Brake fluid will absorb moisture and will rust from the inside out.
Also, the flexible hoses can collapse from the inside (swell shut) with age. So, if you aren't getting fluid from a particular corner, the hose is suspect..

 

The issue I'm having (and it probably isn't an issue) isn't with a mushy pedal, like air in the system, but rather a firm pedal, as if there were no booster. It's like a have a manual brake setup. It stops fine when you push on the pedal; it just takes a lot more pedal pressure than I would have thought.

 

Green stuff pads. There are a couple different colors and they will stop like a race car. They will also go through rotors but if you want to stop those are your pads. Check them out

 

Are they ORIGINAL brake hoses, master and booster? I'd try and separate the master from the booster and look for fluid in the booster and seepage from the back of the master. (It's worth a look. It's free and also, you can't compress a fluid, so that could be it)
Is there a good stream shooting out from the bleeders when peddle is depressed? Does it go all the way to the floor or stop mid way?
If its' just dribbling out of the bleeders, the hoses are probably collapsing. (and they tend to hold pressure to after release of the peddle!)
I usually pull the bleeders, run a tiny drill in the holes to clear dirt. Smear some grease on the threads and re-install. The grease helps them NOT to suck in air while bleeding.

 

I should have mentioned that the previous owner replaced the booster and it looks new. I replaced the master cylinder, front calipers, hoses, pads and rotors. There is no air in the system. I just was expecting more assist from that booster I suppose.