OK, I have a pretty small problem. My brakes SUCK. I don't know what's causing it.
I have a 78 F150 4x4, std. cab.
Basically, The brake lines are new from the proportioning valve to the rear wheels. I replaced the master cylinder. I replaces the front right brake hose(and caliper). the left is fine. The entire rear end is new. Axle, brakes, wheel cylinders. I had to replace the brake lines to the proportioning valve from the master cylinder.

I took extra time to make sure everything was bled well. The master cylinder was tricky though, cuz as soon as you got the bleeding kit out of the way to put the line on it started leaking, probably introducing air.

Anyways. The problem I have is that the pedal goes way down to the floor(not all the way, but more than I'd expect). Then from there I have barely any braking power. I have to stand on the pedal to stop. And then it doesn't seem as hard as I would expect it to be. I did notice that when I step on the brake, the whole power booster/MC system moves down and to the right. Is this normal?
The PB doesn't seem to leak, it doesn't change idle RPM at all.

Should I go through and rebleed everything some more? Is that PB/MC system moving my most likely problem? How could I fix that?

Thanks for your inputs. I have the truck parked in my driveway right now, but I have to start driving it soon.

Thanks all.

 

There should be NO movement of the MC! It sounds like one of the bolts holding the MC in place is broken. The MC expects to see several hundred pounds of pressure from the leverage of your foot being amplified by the pedal itself.

The brakes on these trucks aren't all that great to begin with. That's why everything's got to be perfect. Were the brakes always this crummy since you've owned the truck, or just after the recent work was done?

Please don't be offended, but just to make sure... When bleeding, use a clear plastic hose stuck on the cylinder bleed valve nipple that goes down into a container of brake fluid so NO air can be sucked back and close the nipple before the pedal goes to the floor and stops. Bleeding brakes is a two person job.

 

It is also important to use teflon tape on the bleeder threads otherwise you will introduce air back into the system through those threads when you open and close the bleeders. Get the yellow tape which is rated for petroleum and gas products.


Stock Man
1967 Galaxie 500 Convertible (HELP!---I need 15 x5 factory rims)
1967 F-250 FE 390 4wd
1966 F-250 I6 240 2wd LWB Flare Side
<a href="http://www.hometown.aol.com/tbeeee">http://www.hometown.aol.com/tbeeee</a>

 

>There should be NO movement of the
>MC! It sounds like one
>of the bolts holding the MC
>in place is broken. The MC
>expects to see several hundred pounds
>of pressure from the leverage of
>your foot being amplified by the
>pedal itself.
>The brakes on these trucks aren't all
>that great to begin with. That's
>why everything's got to be perfect.
> Were the brakes always this
>crummy since you've owned the truck,
>or just after the recent work
>was done?
>Please don't be offended, but just to
>make sure... When bleeding, use
>a clear plastic hose stuck on
>the cylinder bleed valve nipple that
>goes down into a container of
>brake fluid so NO air can
>be sucked back and close the
>nipple before the pedal goes to
>the floor and stops. Bleeding
>brakes is a two person job.
>


The brakes have always been that bad..since I've owned it. The MC has always moved.. Actually though, it's the MC AND the PB, the PB canister actually deforms and lets the MC move how it does.

I had to redo the rear brakes cuz of the new axle, and I had to do the front right becuase the caliper was siezed, and brake hose was BADLY frayed.

Oh, how important is it to actually pull out that little rod in the proportioning valve when bleeding? I have yet to do it, and my dad never did it on his '79, so am I again doing something drastically wrong?

Thanks much,
Matt

 

>It is also important to use teflon
>tape on the bleeder threads otherwise
>you will introduce air back into
>the system through those threads when
>you open and close the bleeders.
> Get the yellow tape which
>is rated for petroleum and gas
>products.
> Stock Man 1967 Galaxie 500 Convertible
>(HELP!---I need 15 x5 factory rims)
>1967 F-250 FE 390 4wd 1966
>F-250 I6 240 2wd
>LWB Flare Side <a href="http://www.hometown.aol.com/tbeeee">http://www.hometown.aol.com/tbeeee</a>

That's the first time I've ever heard of that.. Nobody I know of has ever used teflon tape on bleeders.

 

Matt, maybe you learned something today give it a try. Stockman has a lot of good ideas.

John

 

If the valve has a wire coming out of it, then I think that rod just keeps the brake warning light off. Basically, if the rod is centered, then the pressure is equal in both sides of the system, hence no leaks. You can 'bleed' the rod to the center 'off' position by bleeding one side or the other until the switch is off.

 

Thanks for the compliment John....it does sound like a strange idea, but when you consider that threads are not air tight it begins to make sense. Air is your enemy on a brake job. Therefore, you must eliminate all sources which might cause the introduction of air into the system.


Stock Man
1967 Galaxie 500 Convertible (HELP!---I need 15 x5 factory rims)
1967 F-250 FE 390 4wd
1966 F-250 I6 240 2wd LWB Flare Side
<a href="http://www.hometown.aol.com/tbeeee">http://www.hometown.aol.com/tbeeee</a>

 

Matt welcome to the club. I have a 79 ford bronco with the same problem. I have replaced every thing but the truck.I have blede the lines till my arms hurt to no avale. Phillip,gave me a way to try and bleed them see my posting on page one 4x4 Brakes to see if this help and let me know because I can't do mine until after xmas. Your MC oand booster should't move if it does check your mounting bolts. Good luck.

Dan

 

My uncle just gave me this idea the other night. Is it possible that that proportioning valve can get gunked up or something and make them not work right? It's the only thing I Haven't had off or changed.

Matt

p.s.from what I can tell, my mounting bolts are all tight. The whole firewall moves (flexes) when I hit the brakes, not just the MC or the PB. I have no idea how to fix that...

 

Maybe you should take a closer look at your m/c. The cups inside might be hooped(junk) due to a negligent rebuild or reman job. I bought a defective one once. Good luck.

 

>OK, I have a pretty small problem.
>My brakes SUCK. I don't know
>what's causing it. I have a
>78 F150 4x4, std. cab. Basically,
>The brake lines are new from
>the proportioning valve to the rear
>wheels. I replaced the master cylinder.
>I replaces the front right brake
>hose(and caliper). the left is fine.
>The entire rear end is new.
>Axle, brakes, wheel cylinders. I had
>to replace the brake lines to
>the proportioning valve from the master
>cylinder.
>I took extra time to make sure
>everything was bled well. The master
>cylinder was tricky though, cuz as
>soon as you got the bleeding
>kit out of the way to
>put the line on it started
>leaking, probably introducing air.
>Anyways. The problem I have is that
>the pedal goes way down to
>the floor(not all the way, but
>more than I'd expect). Then from
>there I have barely any braking
>power. I have to stand on
>the pedal to stop. And then
>it doesn't seem as hard as
>I would expect it to be.
>I did notice that when I
>step on the brake, the whole
>power booster/MC system moves down and
>to the right. Is this normal?
> The PB doesn't seem to
>leak, it doesn't change idle RPM
>at all.
>Should I go through and rebleed everything
>some more? Is that PB/MC system
>moving my most likely problem? How
>could I fix that?
>Thanks for your inputs. I have the
>truck parked in my driveway right
>now, but I have to start
>driving it soon.
>Thanks all.


I notice that you also said in a later reply that your power brake booster was deforming. Seems to me that if you have a bad booster pump (leak in the diaphragm, vacuum hose, etc.) that would cause most of your problems because at the bottom of pedal travel you are going to be using all foot power with no booster power to help you stop the truck and I'll bet that flexes the whole firewall!(and your leg, knee, etc.) . I say most because they are still going to be Ford truck brakes.

 

If its any help. There were some years with the fire wall cracking and flexing. But this was most notice on standard tranny trucks. clutch would not engage right. And when installing this from Ford there where usally stress cracks behind the master cylinder. Just my two cents.

 

That's what I was somewhat thinking, but my dad and uncle managed to shoot me down with that. (the PB being bad, so I have to use the leg more, making the firewall flex, instead of barely using the leg and the PB doing all the work on the other side of the firewall, hence not flexing.) Does that seem like what your saying? I may replace the PB just for the hell of it.

Matt

 

Matt, a couple of things here..
the booster could be bad, check the line from the mainfold to it, to make sure no leaks. Pull the mc from the booster and turn the rod out two turns. Put a pencil mark on it for refference, and measure to make sure that you are turning it out.
This is a simple procedure, and don't loosen any brake lines.
You will cause the pedal to reach maximun farther from the floor.
If the booster is working properly, you would not have to push the pedal hard at all. I have to feather mine to keep my nose off the glass.
John

66 F100s
In the still cool hours of the night, you can hear chevys rusting away.