No Brakes

[jmhulsey]

I recently converted over to power brakes( bought for a 81 CJ) on my 78 CJ and I cant get a pedal. I bench blead the MC and have blead the lines many times. When I am bleeding them the pedal is stiff and when we open the bleeder screw just fluid escapes, no air. But as soon as I crank it there is no pedal at all. What gives? Oh yeah, the diffs are from a 78 International. I completely redid the brakes, new wheel cylinders, calipers etc. Thanks for any input. Jason

[Dukes69]

Hey Jason, welcome to MJR!

What is your bleeding process?

On the calipers/wheel cly., are the bleeder screw on top?

[rick]

So you are saying when you start it the pedal goes away? What happens when you disconnect the vacuum source from the booster? Does the pedal still go away when you start it?...

[jmhulsey]

I always start with the rt rear/lt rear/rt ftont/lt front. As far as the booster being unhooked I have not driven it with vacume unhooked. But I have jacked up the rear stepped on the brakes and can still turn the back wheels with my foot. I adjusted the rears until they just scrubbed. I have read that it may be necessary to change the MC to a unit off a E350 van (of what year I do not know) because of a larger flow. I would think I should at least have some pedal as it is. Another thing, has anyone swapped International Dana 44 into there jeep? Did you run into same brake problem? Thanks, Jason

[D4x4Fish]

If you pump the brake pedal does it build pressure then? if so change out the proportional valve.

I use a vacuum pump to bleed my brakes.

If you have someone pump and hold the the pedel before you open the bleeder valve and close it before they let up on the brake pedal?

Are your brake shoes adjusted?

My to :2:

[rick]

... the pedal is stiff and when we open the bleeder screw just fluid escapes, no air. But as soon as I crank it there is no pedal at all. What gives?...

This says "as soon as I crank it". What does that mean? When you start the engine you lose the pedal?

[jmhulsey]

Maybe I should have explained myself better. I am positive that my bleeding process is correct and the shoes are adjusted. The problem is after they are bleed the pedal is firm right of the top of the swing, this is what led me to believe they are bleed and working fine, but you begin to drive it and the pedal will go to the floor with no noticable stopping power. You can pump it rapidly and get some response. Thanks Jason

[rick]

You either have a bad MC or there is air in the system. There are no other variables. Is the MC new? If it is, you could have gotten a bad cylinder. This is not all that uncommon. If it is used, I would bet that is your problem.

[goodtimes]

When buying master cylinders, calipers &/or wheel cylinders, always buy NEW parts. Do not buy "reconditioned" or "remanufactured" parts. These parts are always suspect, as the processes used to recondition (or remanufacture) them is iffy at the very best. The cylinder bores are not honed in most circumstances, they are simply cleaned out with a wire brush. This does nothing to restore the surface finish required for proper sealing, or seal life. It is not worth putting yourself, your family, and everyone else on the road at risk, just to save a couple bucks.

[jmhulsey]

The wheel cyls. are new and the calipers are rebuilt. The MC is new, it is actually the second one I put on it, the first being rebuilt. Is there a way to test the MC?

[Dukes69]

The wheel cyls. are new and the calipers are rebuilt. The MC is new, it is actually the second one I put on it, the first being rebuilt. Is there a way to test the MC?

hook up an inline pressure gauge?

[D4x4Fish]

The proportional valve holds back some pressure in the master cylinder, this helps to over come the springs on the drum brakes. Dish brakes side the press is released. If this valve was bad it would release the reserve press, but if you can pump up the brakes and hold pressure then valve is not the problem. I have had master clyinders hold air in the piston and bench bleeding would not get the air out. I had to use a vacuum pump to suck the fuild through the piston, then bench bleed. When you bleed the brakes does the fuild shoot out or dribble out? Can you hold the brake pedal after bleeding the brakes for any lenth of time? Not sure what else you could check.

[jmhulsey]

If I did hook up a pressure guage inline how many # should it be? I have heard upwards of 4,000#, is that right? As far as the pedal remaining stiff, it is. The pedal feels better than the manual brakes did. This thing is wearing me out, much like the soles of my shoes from doing the Fred Flinstone.