RRranch wasn't talking about the parking brakes being stuck on, he was talking about the rear brake pads not being adjusted properly and if they arent they would cause the brakes to be soft.

 

WoW!! Pretty stupid question coming from a RR engineer who operated air brakes for 30 years. I should have my first cup of coffee before displaying my intelligence, or lack of!! LOL I'll blame that one on Uncle Jesse.

 

I had to see if I could slip that one past anyone

 

LOL

 

A bad booster would make the pedal rock hard.
On some gm's a leaking booster under vac will
lock the brakes.


Have the bulletin? It has to be for something else.


My .02 is the master is bad.

Bill

 

I was talking about the parking brake being stuck. If the lever on each rear drum does not release completely then your wheel cylinders have to move whatever amount before they even touch the shoes every time you press the pedal. THAT MAKES A SOFT PEDAL.
Don't believe me go look real close at one. Look how the parking brake assembly works on drum brakes. Boy someone sure likes trying to point out ways that I'm wrong even though he hasn't gotten me yet.
That service bulletin is easy to look up. You can do it yourself. Just google zero loss brake booster. When the old one goes bad it causes fading pedal, soft pedal and a low pedal. Sometimes all three.

Ya know I get on here to help people. I actually do know what I'm talking about. I admit it when I don't and ask for help. People trying to point out ways I'm wrong is getting annoying.
The master could very well be bad but without seeing it all any of us are doing is making educated guesses. Well some of us are. Some are just trying to argue.

 

1997 and earlier diesel trucks equiped with vacuum power brakes--Low/creeping pedal:
Many owners have complained of a low or creeping brake pedal on their trucks, often mistaken for a bad master cylinder or Rear ABS valve. If the condition occurs after the vehicle has come to a stop, and no other brake concerns are found, (worn or out-of-adjusted brakes, cocked pads, or hydraulic problems) the condition is normal and the result of the vacuum pump replenishing the vacuum inside the power booster. Ford has developed a Zero-Loss Travel brake booster to correct this condition if the customer finds it unacceptable. This part is only for use on diesel-equiped trucks--P/N F5TZ-2005-CA--and is not a service replacement; it must be ordered by the part number, not vehicle application.
This condition is similar to the low brake pedal concern on all 1995 F-series that required a larger-diameter master cylinder:




Still make no sense at all? I guess I was just talking out my tail pipe huh?

 

Not trying to argue , I just want poster 's with problems ,to get good info ..

 

We know about that issue & it is not the same thing as a soft pedal ..

 

It's not? How do you figure that? I guess you have never had to talk to customers about their brake problems before. Low, creeping, soft, whatever. It is the same thing. Like I said. I was trying to help. You're not. So how about get back on the topic and try to help the guy.

 

I was trying to help ,not just spewing info . The OP has a soft pedal that he can pump up momentarily . That is not covered in the bulletin. You are mistaken on the rear parking brake making the pedal soft . If It is on ,or partially on , the cylinders are already extended to start out with . The pedal will be higher . The rear cylinders retract from spring pressure ...

 

Would you go pull one of your drums and look real close at the parking brake levers. Look at the cam assembly at the top. Move the lever inboard and see how that cam forces the top of the shoes off of the wheel cylinder. I am not mistaken. Go look. Seriously. If that parking brake lever is not completely released then it will cause a low pedal. I've been working on these a while now and know my brakes.

You have two separate and independent brake systems on the rear drums. One hydraulic actuated by the wheel cylinders forcing the top of the shoes out against the drum and one mechanical that works through a cam and lever which overrides the hydraulic system and forces the shoes out at the top. The mechanical brake cam will force the top of the brake shoes out of contact with the wheel cylinder. When this happens you have to press the pedal down farther to overcome that gap before you get good pedal. That is a "low pedal"

If you adjust your brakes with the parking brake released fully at the drum then you WILL have a low service brake pedal when the parking brake is engaged or when the parking brake lever is stuck. The cure for it is complete dis assembly of the parking brake system in the rear, thorough cleaning and lubrication of the contact points between backing plate and shoe and the anchor pin and cam assembly. Often frozen or rusted parking brake cables also cause this problem. The way to know if yours are stuck is the levers should almost be touching the edge of the backing plate when released. If not then something is stuck.

 

Pump the pedal once & the cylinder will catch up & stay there till the springs can retract it again ...I don't need to go look ...

Take the shoes off & pump the brakes & tell me what happens ...

 

Whatever, you know everything so I give up. I hope you pay someone else to do your brake jobs though.

 

Ouch ...

In the 6 thousand or so posts I have here , How many of them were from me whining about something I couldn't figure out ?

I will admit that there are plenty of things on the PSD you know quite a bit more about than I . This is not one of them....