Xjtre

Just recently replaced the brake pads and bled my brakes on my 90 xj and everything was fine for a week now recently my brakes will stop working not long after I start driving then right after they stop working they work again it happens every time I go to drive anyone know what’s wrong with them?

gat

Since most braking is in the front, then the issue is likely there. What is the condition of the soft brake lines in the front. Is there any leaking in the front at all, anywhere?

Xjtre

No leaking that I could find and I only have front brakes my rear are not connect. The line is plugged off but has still been bled this hasn’t been a issue before

BimmerJeeper

Could be master cylinder?
https://www.cherokeeforum.com/f2/bra...travel-246108/

caged

did you do anything with the calipers? remove them or replace them?

you said the rear are not hooked up, the line is plugged off? maybe that's where the problem is. how is it plugged off, and more importantly, why?
it's not that hard to repair the rear brakes to make them work, so what went wrong with the rear brakes as to why you plugged them off?

gat

I'd convert my rear brakes to disc before I decided that I wouldn't have rear braking. How do you park?

I am very curious how to stop the flow to the rear, yet are able to bleed that line of possible air...

fb97xj1

Reconnect the rear brakes so they are back to how they should be, then troubleshoot it. The rears are just as important as the rest.

Xjtre

The rear brakes were disconnect because I had to do a axel swap in a hurry I put a ford 8.8 on and the brakes were in extremely bad shape filled with grease and mud and unable to use so I put a screw up the rubber line to stop the flow and when I bled the brakes I used a drill to get the screw out to release the air then put it back in. But I think it is the brake booster

jake92

Always take time to do upgrades, it's a good thing that your 8.8 didn't decide to part ways since you were in such a hurry. You should have went through and fixed everything on the 8.8 before swapping it in.

and huh? Why do you think it's the booster? Without having the brake system in it's factory setup, you are just guessing why things don't work.

XJwonders

That’s ****ing dumb to not hook the rear brakes up. When doing stuff very important like brakes. You absolutely have to do it all at once or not do it. That’s pretty regarded move that you made there... endangering yourself AND others

BEFORE YOU DO ANYTHING ELSE. FINISH THE BRAKE JOB. And then we will help you.

Xjtre

Brakes are hooked up in the rear and now they only stop working when I turn hard right then I have to pump them up

lawsoncl

Is the vacuum line to the booster leaking? Is the pedal going down further than normal, or just firmer and not working as well like the booster doesn't seem to be working?

papablista

It might be the proportioning valve also.

dave1123

BINGO! Exactly what I was going to say after I finished reading the whole post. On today's dual circuit braking system where the front and rear brakes have separate master cylinder pistons, if you loose pressure in one circuit, there's a valve that will close off that circuit and still give you brakes in the other. There's also a proportioning valve that limits pressure to the rear brakes because drums require less pressure to set than discs. My 67 Camaro gave me fits because it had a DELAY valve in the rear brake line that if you hit the brakes hard, would delay the buildup of pressure to the rear brakes with a bleed orifice, but all 4 brakes would work normally at normal pedal pressure. This car had 4 wheel drum brakes. I took the spring and piston out of that valve because I autocrossed that car and needed instant braking.

Basically what I'm saying is braking systems are more complex than you think. It's true that the front brakes do about 75% of the braking, but the rears do a lot more than you think. Without rear brakes the car can become uncontrollable under heavy braking in a turn.

A vehicle may not accelerate for beans, but it HAS to be able to stop! Anything else can become deadly. FIX THE BRAKES!

Xjtre

Brakes weren’t an issue to begin with I noticed my driver side tire was leaning in only to discover 2 bolts came out of my hub god knows how because they were torques to spec but after replacing them my brakes were working fine.