Somebody help before I burn this jeep!

I have been fighting a brake problem for months. I have about had it. I am ready to sell the jeep for scrap if I cannot get a working master cylinder into it soon.

I went through my brakes from the MC to the shoes, everything is new. the MC I got is from advance auto. it looks just like the original except the ports are larger. I added adapters to get my lines to fit and it bolts right in.

when I press down on the pedal, the rear brakes work but not the fronts. the pedal seems to stop hard about half way down.

I have checked for obstructions to pedal movement
I have tried my old mc to see if it would work and it did but it leaks internally
I have disassembled and properly bled the new MC before reinstalling it.
I have said more bad words than I care to over this derned project.
I am getting tired of having a jeep that does everything well but stop.

where can I get the correct replacement for this MC?

 

Could the lines be hooked up backwards??? Front to rear lines reversed?? I have had a few new MC's that were bad from the parts store. Exchange it and try again.

 

Sorry to hear it Randy. Heck flip the lines see what happens, whats the worst thing that can happen??? no brakes?

 

Randy-

Check Jeepdoc.com. They'll take care of you. Prolly a bad MC from advanced auto. Get the right one, you'll be ok. I went throught this with the wheel cylinders. Brand new and one was bad It happens...

 

Walck's here in PA should stock it. Had good luck with him. Not so good with the big chain stores.

 

just a couple thoughts Randy
are we getting juice out of the front wheel cylinder bleeder screws ?
it should be a good blast if someone is pushing pedal for you.
are you using the old m/cyl push rod ?
did one come with the replacement m/cyl ?
are they the same length ?
is yours too short ?
do you need a longer push rod to make the replacement work correctly ?

 

the lines are hooked up to the MC the same way they were when I got it. the brakes worked then...

With the MC out of the jeep, a push on the actuator rod puts out a good blast of fluid from both ports. Pressing the pedal while it is mounted in the jeep will put fluid out of each wheel cylinder, but not the amount the old mc pushed. I am using the rod from the old mc, there was not one included with the new MC. with it mounted in the jeep, the rod reaches to the same point it did while mounted on the old MC.

I ordered another MC from AutoZone this time. it will be in tomorrow and I will give it a try.

thanks for all of the input.

 

Is the Master Cylinder Dual Reservoir? If so its might have a residual valve in it (used only for disc brakes)! This would acount for your having breaks in rear and little to none in fronts!! my $0.02

 

Welp, I just got back from auto zone with another new MC and guess what I noticed...

the ports are actually labeled front and rear.... the front being the closest to the pedal.

my original had the front brakes hooked to the other port. so I pulled the old one out of the scrap metal pile and low-and-behind, it is labeled also. the port furthest from the pedal is labeled front...:?

somewhere along the line someone decided to build a different MC to fit these jeeps.

I recall a recent dsicussion here on ECJ where it was determined that the original setup had the front brakes hooked to the front of the MC and the rear to the rear. obviously to get these to work correctly I will have to reverse the setup.

 

Good to hear you figured it out. I wish I had known where you lived since yesterday I went right by your house on the way to Rudy( or however you spell it) inlet.

 

Wow! I'll bet that discovery is a relief?! Glad to hear you tracked down the culprit. Now go grab a and fix this baby!!

 

The frige is outa :stout: and I am outa steam. it will have to wait until tomorrow:evil:

 

Well, should you happen to do that again, give me a yell

 

I will, hopefully I will be heading down that way in the next couple of weeks.

 

How about the distribution block? Is it the correct size/year for yor MC?

Just a thought.

 

Um...dude, that was over 4 years ago

 

Yeah $sink seemed to be driving well when I was in it. Other then that ejection seat you call a passenger seat R)

 

If I remeber from when I went to mechanic school at Johnson College years and years ago....
the front goes to the front of ther master cylinder- the idea being (me thinks I remember), the front brakes are the most stopping power, (pre proportioning valve days), so the master cylnder plundger pushed the MOST fluid to the front.
Sounds pretty simple as I type it, but I guess it makes sense.
I had an "old" school mechanic instructor, (he was great, taught me a ton of old time tricks, have a smoke in his mouth, a inhaler, a terrible hack. He'd be smoking outside, hacking up a lung, spray his inhaler and smoking!).
I was doing a Jeep pickup truck over then, (my first jeep rebuild), who told me to use a 1 size smaller wheel cylinder dia. cup.
This would cause a increase in PSI at the cylinder, moving them FASTER, and making the front work better, (He like the idea that I was into old jeeps, cars).
Just a little bit of info I remebered as the cafine is rushing into my 2 working brain cells!
Glad you figured it out
Joe
Franks Shaffer would always scream, (and then hack!)- "A technician tests, not guesses"!!!