brake wont work after lift, tried everything

[hatched91]

I put on a 5.5" superlift w/ procomp extended brakelines. I went to bleed the brakes and all four wheels bled fine, they shot good streams of fluid. I even bled the master cylinder, and abs lines. When the truck is shut off, the brakes are solid and pump all the way up. When the truck is on, they go strait to the floor. We replaced the master cylinder internals, and still the same result. We drove it around, engauged the abs, and then rebled the brakes. Still, same result. I'm stuck and need help. Any suggestions as to what's wrong?

 

[hatched91]

after reading "brakes won't work after draining fluid", i also came the the conclusion that the booster could be bad. Someone posted that it shouldn't be bad if there was air being sucked in whenever you pulled the plug. Indeed, whenever i pulled my plug it was very difficult and seemed to have plenty of vacuum. So, as it seems to be, the brake booster is good, just replaced the internals on the master cylinder ( because i stripped the rebuilt one i bought so i just switched housings ). Still, brake pedal pumps up when it's off, turn it on, strait to the floor.

 

[Bruces expo]

good luck on the fix thats kinda dangerous atleast you found out the easy way good luck

 

[Vanquish502]

Since theres only vacuum when the motors running, and you only seem to have a problem when its running, its apparently a vacuum problem. As for what I'm not sure, but this should be a good start.

 

[hatched91]

there is also vacuum when the motor is off. I can pull the plug when the motor is shut off and you can tell there is pressure.

 

[hatched91]

the only thing i can think of is the module that you plug in to trick the abs or w/e it is that it does.

 

[Creager]

There is going to be residual vacuum in the brake booster when the motor is off. You release it by pumping the brakes, that’s why the petal eventually gets stiff with the motor is off.

It could be that…

1 - Your rear drums are not properly adjusted, or the hardware for your rear brakes is worn out and/or ****ty.

2 - You have air trapped in your system somewhere. Maybe the calipers upfront are leaking, not holding pressure? (I had some new ones out of the box that did this) Maybe there is air caught at the ABS valve? You did bleed starting from the farthest valve from the master cylinder, to the second farthest away and so on, correct?

3 - You have DIRTY fluid in the hydraulic system. Did you bleed all the way through? Got all the black, grimy **** out?

 

[hatched91]

when i replaced the rear wheel cylinders(because the bleeder screws broke), i put the brakes together exactly how i found them, no adjustments made. The system has been bled several times, like 10 and i keep putting new fluid in the system, so there isn't any old grimy fluid in the system. I have been watching for leaks and there are none. one of the rear wheel cylinders was bad and leaked strait out of the box, so i replaced it again and no leaks now. The system has been bled at every point. The master cylinder, the abs unit, and at all wheels starting farthest from the master cylinder. I think i just need to take it to a shop and have the abs primed with the plug in tool, and then bled. I would just take out the abs, but i cannot find a two-to-one "Y" or "T" adaptor. They just don't have those parts at auto-zone, advanced auto parts or o'reilys. Otherwise, i'd just get rid of all of the abs. what should i do now? is it time to give in and take it to a shop?

 

[Creager]

How old are the rear brakes? Im reluctant to say this is your problem by the way you said you put it back togeather exactly how you found it, with no adjustments. Older drums/shoes and hardware takes a little bit of trial and error to get adjusted just right. I've had this same issue you are having problems with, and it was just the drum brakes being picky.

Before i tell you to do something else, i want you to remove your rear drums. Take notice of how many visable threads (turns) that are on (star) self-adjuster unit near the bottom of the brake assembly.

Ive noticed that with new shoes and drums it takes about 3-5 full turns of adjustment to have the drums seat snuggly on the shoes. With older drums and shoes it was like 8-11. But dont just follow that, push inward the backing plate (behind the star-adjuster) and turn the adjuster out to like 5-7 visable threads. Then attempt to replace the drum.

If the drum takes a lot of force to put on, then you need to back off a turn or so on the adjuster. If the drum practically falls on, then you need to extend the adjuster out by a thread or so. The drum shouldnt just slip on and off, but it shouldnt need to be beat on with a hammer/mallet either. When you turn the drum/axle by hand, you should feel a little bit of resistance from the shoes.

With older drums, there will be a groove on the outter lip of the drum. If this is the case then you need to get new drums or have yours re-surfaced (because this lip makes it difficult to put the drum on, when its actually a loose fit once you get over that groove.) If thats the case you can adjust the drums from behind the wheel cylinder through the little 'dust hole.' There is a special tool for it, but i was able to do with two screw drivers.

 

[hatched91]

thanks for the help, i'll try it. But wouldn't the truck stop with just the front calipers? i meant not like it should, but at least come to a reasonable stop? i mean i know the rear does 60% of the work, but it doesn't feel like the front is doing it's 40%, more like i'm getting 15% total braking.

 

[Creager]

Actually its the oppoiste, front does 60%

Actaully, heres a little test. Drive down the street and slam on the emergency brake... with no other braking input (so its just the rear brakes), report back the results.

You will be surprised, with no rear brakes, it stops but it takes TOO LONG. no slamming on the brakes possible.

 

[hatched91]

that was it...when i SLID the rear drums off, the adjusters fell out! I used a crow bar and pryed the pads apart while i adjusted the adjustment screw. I then put it all back together and i press the brake pedal and about 1/4 of the way down it starts grabbing. I slammed it, and the abs kicked in for the front, but the rear locked up? oh well, i'm going to pull the fuse anyways, i hate the abs. I guess some fine adjustments (and new pads) and i'll be ready to go! thanks a lot!

 

[Creager]

If the rears are grabbing more now you might have them adjusted too much... its definatly possible. Its possible to get them so tight that its like having the parking brake on at all times... Fine tune it! Practically speaking, you have to (fine tune) everytime to ever get them to work right. Its also good to clean the hell out of those threads, and coat them with a thin layer of grease. They are supposed to 'self-adjust' as the shoes/drums wear.

if yr putting new shoes (pads) on the rear, do the drums too. this problem will NEVER completely go away if you dont, trust me... it took me months to just figure out the hard way.

 

[hatched91]

alright..i plan to do a rear brake job next week when i get paid. I noticed on the passenger side there was a cable that connected from the top pivot point of the shoes to the bottom spring, and it looked as though it ran on the adjuster i guess that's the "self-adjusting" part. It isn't on the drivers side though. I guess it's suppposed to be on both sides, if it is, i'll take a trip to the junkyard and pick the parts up(need to go for fenders anyways). I will take and get the drums turned when i get the new pads also.