jeepsurfer1

Okay so over the last few months I have been fighting my brake system and I need your help figuring out what it could be,

My symptoms, will I have had the brakes go out on me completely once, I'll only been driving for aproximately 3 minutes, and it was like all my brake lines popped off so I drifted down put it in a ditch waited 15 minutes start it back up and I had breaks again so I drove it home and park it for 2 weeks until I could work on it and it was a leaky master cylinder I'm telling you that because I have a similar problem this time , this time the brakes are slowly fading again I've never had a really firm pedal like I wanted/should have.

Now your questions are probably something to the tune of what do I have, so it's a long list lol it started of life as a...

96 jeep cherokee
2002 Grand Cherokee booster and master
8.8 rear, disks
- all stock 8.8 brakes, has new pads as well as new calipers and rotors
D44 front disks, this is where it gets complicated
-88 waggy calipers and pads
Ford brake rotors (95f150) all new as well
Also for what it's worth all this of the soft lines are rc ss braided
Also I've bled the brakes 8 times, including having several professional shops power bleed them to no avail, if anyone has any ideas my ears are open, I have brakes but I just have no firm pedal and it seems like everytime my pedal keeps getting softer and softer

jeepsurfer1

Both master and booster are not leaking this time

93gc40

If you are losing fluid find and fix the leak. IF you are NOT loosing fluid, start by replacing/rebuilding the master cylinder and booster. Do you have good vacuum.. You do still have your egg, right.

jeepsurfer1

The rotors do line up perfectly in the caliper, and the rotors or actually slightly thinner then the rotors that went with that caliper that said they do rub I believe

jeepsurfer1

booster holds vacuum just fine and I'm not losing any fluid unfortunately, that would make for an easy fix and as you can tell normally I can figure out most of my own problems, this 1 actually has me stumped, also egg?

jeepsurfer1

Wait by egg you mean, the vacuum canister, yes I still have it lol I've never heard it called egg before, but considering how easy they are to crack, its well put

93gc40

Egg is the vacuum reservoir, that most customizesr remove.. Not really needed for motor operation. But a must for things like vacuum operated/assisted, brakes and other accessories.

If the rotors are rubbing the caliper could be preventing free movement and proper pad seating

jeepsurfer1

Okay I don't think that's the problem but I'm very open minded and willing to try anything so how to check for alignment of the pads?

jeepsurfer1

I now have no idea, I pulled the master and checked it its not leaking fluid out of the back it could still be internally leaking but, I'll save that for later, I checked every connection with the brakes pumped up 10 times and held down there aren't any leaks unfortunately so I'm back to square one

Boostwerks.com

Sounds like a bad master cyl to me.

jeepsurfer1

It's the second one lol but I'll put a order out for one in a few

jeepsurfer1

It's the second one lol but I'll put a order out for one in a few

Jeeperz71

Did you ever check to see what the vac reading is at the port that feeds the brake booster on your intake?

Jeeperz71

I would put it all back together and attach a vac gauge between the booster and intake and run a hose out with a tee so the gauge is OUTSIDE of vehicle. Then I would drive after full warm up and check the vac readings under load. Maybe with rolling mass the booster might not be up to par. Maybe you need larger bent tubed lines at the M/C and porp valve for more initial fluid pressure. It sounds like pressure bleeding off slightly and that could be signs of weak vacuum.

jeepsurfer1

Okay I got a vac gauge at the house ill just run off of the intake and set it next to the wipers, what should I be looking for?

Also the booster and master are a huge upgrade for 84-96 XJ's so Im sure they can push the pressures I need, and how would larger lines help?