Bakes issues, work uphill but not going downhill - losing my mind.

[lshobie]

Hey guys

Having an issues with my brakes and I'm ready to blow this truck up now. I've bled the system about 50 times, every way i can think of, with vacuum pump, 2 new master cylinders, bench bled the master 3 times, I've put about a gallon or more of fluid through it - probably 2 gallons. not getting any air out now. bleed system, nice and tight for a couple of pushes but then gets softer - rears are locking up but not fronts - this is on level ground.

if i drive up a slight incline - maybe 3 -7 degrees i got front brakes no problem.

if I go down hill basically on the same road just different directions i lose the front brakes.

I did tear out all the old brakes lines as they were rusty and crappy, got rid of the lspv at the back axle as it was seized and a nightmare. I installed an adjustable in line rear pressure adjuster so I can either give the front and rear 50/50 brakes or give the fronts more - which is what i wanted. all new brake lines - coated. i double flared all the joints and have no leaks - nothing leaking out and nothing leaking in.

brake booster is fine.

Any ideas??? I'm ready to buy all factory lines and that retarded rear lspv but i dont' want to. Oh, all the brakes just replaced - new calipers, rotors, drums turned. When i drive uphill the truck stops on a dime, short of driving only uphill everywhere I can't figure this one out.

Thanks!

 

[Behemoth60]

Having an issues with my brakes and I'm ready to blow this truck up now.

Dumb Question... Are the Calipers on the correct side, left to right?
The bleeders need to be at the very top of the Caliper, if they are reversed, this is exactly opposite and impossible to bleed.

 

[kbushnz]

Has the master cylinder been bleed fully...
They can trap air in them...
And it wont push thru the lines...
Here is a good vid which you could replicate in the truck...
Dual Brake Master Cylinder - How to Bench Bleed (Moss Motors Tech) - YouTube
I have done it by cracking the lines one at a time and bleeding it into a rag.... locking it off on the back stroke...so it doesnt suck air back in.....But its a bit messy.....
Just need two people....

 

[roscoFJ73]

if i drive up a slight incline - maybe 3 -7 degrees i got front brakes no problem.

if I go down hill basically on the same road just different directions i lose the front brakes.

Thanks!

Louis do you really think its the incline itself ? If you were going uphill much less braking power would be required so you wouldnt have to put your foot on the brake as hard.

I know you wouldnt do this,but do you have the brake caliper lines crossed? We had a thread once before that ran to about 7 pages and thats what it was

 

[Squash]

Whoa now Louis,

Start off easy, jack her up, take off all four wheels, pull the pads, stick in some wood and now press the brake pedal.
If help is available have them brake while you scurry around watching the calipers bite and release.
From this observation troubleshoot up the line.

 

[Radd Cruisers]

Here are a few things to check:

- Brake pedal height.

- Brake pedal return spring.

- Protrusion of the (adjustable) pushrod from the booster into the master cylinder. If this is not adjusted correctly when you install a new master, the brakes may not work properly.

- Fluid contamination inside the brake booster (partially filled with water, brake fluid, or some other fluid.

Part of what I am getting at is if the brake pedal is very slightly partially depressed, or if the pushrod that sticks into the master cylinder is slightly too long, or the pedal return spring is missing (having the same effect as the pedal being very slightly depressed) then the slight mis-position of the piston in the brake master will block the fluid inlet holes into the master thereby preventing proper operation, causing what you're talking about.

Best of luck with this.

~John