ok new problem, I need help with brakes!

[GRU]

i think this has been talked about before but im not sure. i am bleeding and bleeding the brakes on the 92 dually and not getting any air. without the truck running the pedal is good and hard. soon as i start the truck up the pedal goes to the floor. pump it up about 3 times and it gets firm for a few seconds then slowly goes to the floor. its not leaking anywhere. previous owner said they had several master cylinders in it but it never cured the problem. the only other thing in the system is whatever "thing" is mounted on the drivers ftramerail that the rear brakeline goes in and comes out of to go to the rear axle. it also has a wire harness on it. what is this thing and could it be the problem? i cant tow my camper to the rally without brakes!! thanks in advance!

 

[91idi]

Rabs(rear anti-lock brakes valve) I bet is the problem. Replace,bleed, delete you chose

 

[icanfixall]

My feelings are the rear brakes are way out of adjustment. To test this theroy apply the parking barake down about three clicks. Also where does this peddle set the brakes at. If its more than half way to the floor the rears are completely out of adjustment. Now I know your thinking the rears are self adjusting... But in reality they just do not work. So most of us here self adjust them for proper brakes. They do wear down and when they can't adjust up it takes more brake fluid to fill the wheel cylinders for them to stop you. This is true also if when you come to a stop the brake peddle sinks to the floor slowly till the truck creeps forwards surprising you. When your pumping the brake peddle your pushing more fluid back there to fill the cylinders. Another test is when you set the parking brake down three clicks take it for a SLOW test run. See if the brake peddle stops the truck higher up. What the parking brake is doing is manually spreading the rear shose making them "adjusted"... But bot really a good thing to be doing all the time. When the rears are so far out of adjustment the front are doing overtime to stop you. That will overheat the brakes and the rotors. I cracked several roros before I found this out at a Midus brake shop. Now I self adjust and have never had any more issues with the rears. A hydroboost brake system makes this creeping peddle problem almost go away completely but you still should pm the rears. A hydro and 1 5/16 master cylinder pushes more fluid per brake peddle movement and it doubles the hyraaulic brake fluid pressure to 2200 lbs...

 

[Bootzz]

I had this problem ib my truck. Check all your vacum limes and dpuble check your fluid lines. You have a leak somewheres. I chamged master cylinders, pads, calibers, booster, lines and everything inbetween and i still am fighting a small problem. Mime ive narrowed down to the vacum system. Beat thing exscPecialy if ur haulijb is get a hydro boost instead of sinkin money into a poor system

 

[GRU]

Rabs(rear anti-lock brakes valve) I bet is the problem. Replace,bleed, delete you chose

ok this is just the thing that actully operates the rear abs correct? i HATE the ABS crap, so if i just got a barrel type connector to join the in and outgoing lines thus deleting that unit it wont affect the braking other than i wont have ABS? i think i will do this if for no other reason than to eliminate it as being a problem now or later. i will also adjust up the back brakes too, however i had to "loosen" the drivers side cuz it kept grabbing and i couldnt get the drum back on. the actual "proportioning valve" is that big hex shaped thing on the rear output of the master cylinder right? is there a different one that can be used to up the rear brake bias when loaded heavy, as this truck typically will. i do have a hydroboost that i didnt install yet for two reasons. first is its my heavy towrig. losing steering AND brakes at the same time doesnt lend itself to the longevity of my family. second is i used a compression fitting to adapt my ford PS pressure line to a dodge end to work with the cummins and im not trusting it 100% yet...

 

[Iowa 73]

Went through this on my '92. Switched to hydro boost and fixed my problems. The vac boosters that I tried would not give me a firm pedal, and everything else was good.

 

['94IDITurbo7.3]

could also be a bad booster.

 

[GRU]

hmmmm... i do have another booster. but how does the booster affect the master cylinder? all it does is make it easier to push, right?

 

['94IDITurbo7.3]

hmmmm... i do have another booster. but how does the booster affect the master cylinder? all it does is make it easier to push, right?

let me find the link.

EDIT: http://www.ford-trucks.com/forums/661661-for-those-with-brake-problems.html

 

[GOOSE]

I would put a good eye on the RABS valve.

 

[MIDNIGHT RIDER]

Lots of good suggestions already.

Were it me, first, I would run the back shoes plumb to lock-up, then back them off a few clicks at a time, pumping the pedal between adjustments to keep things centered, until I had wheel rotation with a fairly hard drag.

What icanfixall says is often over-looked; it takes a ton of fluid to spread out-of-adjustment shoes into contact with the drums.


I will amend that; FIRST, I would tear into the drums and check for broken/missing springs and such and also the thickness of the shoes.

Once I knew the shoes were all set to rights, I would DELETE any anti-lock foolishness, PLUS that silly load-sensing gizmo that many dualies have.

The wife's 1991 Dodge/Cummins never did have decent brakes,and ate rotors and front pads, until I bypassed the RWAL junk.


Take that steering hose to a hydraulic shop and have it properly made, crimping new hose on the Dodge and FORD ends; that gear-driven Cummins pump might push things apart.

 

[DesertBen44]

I'm having the same issue 87blue, i'm going to try adjusting the rear brakes on mine and Ill let you know what it changes. Good possibility it will fix it because I installed new shoes/cylinders/drums recently without properly adjusting, which got rid of my grinding issue but cause this...

 

[GRU]

ok im deleting that RABS crap. about the PS hose, isnt there some type of chevy adapter or something of that sort that will allow the factory ford hose end to thread right into that dodge pump? if so i will definately do that!

 

[franklin2]

the actual "proportioning valve" is that big hex shaped thing on the rear output of the master cylinder right? is there a different one that can be used to up the rear brake bias when loaded heavy, as this truck typically will.

When they came out with the ABS, they did away with the proportioning valve, there was no need for it. Most people like me who have bypassed their ABS valve, are just running straight 60's style brakes with no proportioning valve at all, just straight pressure to the front and straight pressure to the rear. If you are worried about it, you could get the proportioning valve off a earlier truck that didn't have ABS, but there will be lots of plumbing involved. I haven't had any trouble with my brakes just running it without a proportioning valve.

 

[GRU]

so what exactly is that big hex thing then? it is a restrictive device of some sorts right?