Need help trouble shooting brakes.

[Twelvebcharlie 10]

Working on my dad and I's 69. The cars been sitting for the last 30 years more or less, and hasn't moved at all up until this summer for at least 20 years.

 

We cant get pressure to the brakes, the pedal goes all the way to floor. The front calipers will just start to grab at the very bottom, and if i pump the brakes i can build up enough to get the rear drums to grip.

 

So far we've, replaced the brakes all the way around. wheel cylinders for the drums, and the master cylinder. We've tried bleeding the brakes multiple times, and the master cylinder itself. We haven't noticed any fluid leaking out of anywhere else. Its gotten better but is no where near safe to actually drive.

 

My uncle helped us work on it today, who's really good with brakes was stumped. Basically we came to the conclusion that it may either be the proportioning valve, or we just got unlucky with a bad master cylinder.

 

Anyone else ever encounter this problem?

[bryonbush 85]

did you replace the brake lines from front to back? what i ran into when i first got my car was the rubber hose to the back of the car was collapsed and wouldnt allow any fluid to pass through. check the rear and the front ones as well. i just went through and re did my brakes front and back. new calipers/rotors/lines for the front and drums, springs, lines, and cylinders for the back and doing good. but check those hoses first since it looks like you got everything else checked out.

[70769 18]

Have you checked pressures at the master cylinder? It seems like youre losing pressure under pressure, are your rubber lines ok? Not bubbled?

[70769 18]

Haha bryon beat me to it... great minds and all

[Twelvebcharlie 10]

did you replace the brake lines from front to back? what i ran into when i first got my car was the rubber hose to the back of the car was collapsed and wouldnt allow any fluid to pass through. check the rear and the front ones as well. i just went through and re did my brakes front and back. new calipers/rotors/lines for the front and drums, springs, lines, and cylinders for the back and doing good. but check those hoses first since it looks like you got everything else checked out.

 

No, only thing we did as far as the brake lines, was flare the old brake line because i broke it off at the wheel cylinder. The rubber hoses, while old, looked fine, except for 1 which was frayed a bit. Again no leakage though.

[j69302 11]

Sometimes it just takes A LOOONG time to get fluid to start flowing on a completly empty system. Try this

 

get a vacuum bleeder that also has a pressure out put. Almost all of them do.

 

Connect the pressure output at the right rear break bleeder, and, with the brake lines disconnected at the master cylinder, put something to catch the fluid. Pump the Right rear brake bleeder with fluid until fluid comes out at the master cylinder.

 

When fluid comes out, close the right rear brake bleeder. And then move on to the left rear, and do the same thing. Once both rears are done, reconnect the rear brake line fittings to the master cylinder.

 

Then the right front, then the right left, and reconnect all fittings.

 

Then Bleed brake normally.

[barnett468 418]

hello;

 

i might try opening one bleedder at a time for five minutes, if no fluid comes out you have an obstruction somewhere. if fluid comes out slow but steadily, let it drain for 2 minutes. refill master then do the rest.

 

of they all bleed but it does not help much i would try bench bleeding the master again with the nose titled upward slightly. then repeat the gravity bleed method.

 

also, i would make sure the safety valve is centered then lock it down during bleeding.

.

[Twelvebcharlie 10]

hello;

 

i might try opening one bleedder at a time for five minutes, if no fluid comes out you have an obstruction somewhere. if fluid comes out slow but steadily, let it drain for 2 minutes. refill master then do the rest.

 

of they all bleed but it does not help much i would try bench bleeding the master again with the nose titled upward slightly. then repeat the gravity bleed method.

 

also, i would make sure the safety valve is centered then lock it down during bleeding.

.

 

Yeah, there is fluid coming out. We've gone through a whole bottle in an attempt to bleed it. It doesn't come out with much force at the rear right bleed, it just barely flows out.

[bryonbush 85]

No, only thing we did as far as the brake lines, was flare the old brake line because i broke it off at the wheel cylinder. The rubber hoses, while old, looked fine, except for 1 which was frayed a bit. Again no leakage though.

 

just a heads up, my bakes looked good with no cracks, but was collapsed on the inside so you couldnt see anything that was wrong. my fronts were cracked and dry rotting but worked good. if you're getting hardly anything out of your back lines, then id place money on that rubber hose.

[Twelvebcharlie 10]

just a heads up, my bakes looked good with no cracks, but was collapsed on the inside so you couldnt see anything that was wrong. my fronts were cracked and dry rotting but worked good. if you're getting hardly anything out of your back lines, then id place money on that rubber hose.

 

The thing is it flows out smoothly, it just doesn't shoot out very far, nor did it pop at all. Also the brakes seem to release smoothly, which I've heard isn't typical of a kinked or blocked line.

[barnett468 418]

your right rear line sounds like it has restricted flow but probably not enough to cause your problem. if you installed the master then pushed on the brake pedal before gragity bleeding, you may have air in the master.

 

did you check to see if the safety valve is off center yet?

 

did you adjust the brakes so they drag slightly on the drums?

[1969_Mach1 333]

If it were mine, I would rebuild or replace the hydraulic components in the brake system, wheel cylinders, calipers, master cylinder (replace with new only), and replace all the rubber brake hoses. I would also inspect the steel lines and all mechanical parts in the brake system and replace any worn or broken items. After sitting that long, I wouldn't feel safe simply fixing only what is currently wrong with the brakes.

[Max Power 74]

What happened to me, and I hear it is pretty common, was there was blockage at the "T" that feeds to each rear cylinder. It's mounted by the diff, and I guess they plug up somewhat regularly.

[70769 18]

Ss braided lines arent that expensive either, classic tube makes some excellent ones. Thats what i replaced my rear axle one with. My fronts are from ssbc.

[70769 18]

But before you throw more money at it, have you bled the mc on the car, since you have it already installed. That way you can see whether its working properly or not and work your way down from there

[mustangmike6996 34]

If you havent already used a vacuum or pressure bleeder I HIGHLY SUGGEST you invest the $25 for the mitivac bleeder (at harbor freight) to complete the job....

 

 

I have done many brake jobs. I have fabbed up partial sections and redone entire cars for lines. 1 tiny bubble in the wrong spot will cause a crap day.

 

The worst car I have ever done was my friends 1987 Mustang GT when we did the 5 lug swap. At the time I had been an ASE master tech for about 3 years at a dealership level. We only had basic tools. I ran all new lines and we had 4 qts of new fluid. We could get the car to build pressure at the end of the pedal travel. The car had just enough pressure to hold it but couldnt stop. We bled over and over and over... over the course of a week. One day he was pumping the pedal and I got one tiny, I mean TINNNNNNY bubble, and he said "oh shit the pedal is rock solid"

 

There was a bubble stock somewhere in the rear lines and that was that.

 

Start at the rear-most wheel and bleed until there are no bubbles, ensure the MC NEVER goes anywhere close to dry. Also, jack up the wheel that you are bleeding... It *might* help get any bubbles out.

[MikeStang 247]

Yep a small amount of air will ruin your day.

I like to keep a rubber mallet handy and i tap the calipers and rear of drum backing plates when I do my bleeding just to help things out if I can.

[Twelvebcharlie 10]

Thanks for the info guys. Cars at my dads place so haven't been able to work on it till this weekend. I think we've decided to replace the master cylinder with another one and if that doesn't work. I'll try what some of y'all have suggested.

[Twelvebcharlie 10]

Thanks for the info guys. Cars at my dads place so haven't been able to work on it till this weekend. I think we've decided to replace the master cylinder with another one and if that doesn't work. I'll try what some of y'all have suggested.

[barnett468 418]

make sure their is proper clearance between the rod in the power booster and the master as i mentioned.

[barnett468 418]

make sure their is proper clearance between the rod in the power booster and the master as i mentioned.