Brake Problems

[ZachStack]

Alright. so when i got this truck the brakes pedal would go to the floor and the brakes are very weak. but its got a new vacuum pump hoses master booster lines calipers wheel cylinders. I do not know if the rear brakes on this truck are self adjusters or not but ive drove around in reverse and hittin the brakes to adjust em but it doesnt help. sometimes if the rpms are still up on it itll brake just fine....but i cant find any vacuum leaks anywhere. any advise? anyone with the same problem?

 

[79jasper]

You need to check out your brakes. Look at the rear shoes. And lube the self adjuster.
You will need to adjust the brakes.

 

[Oog]

Are you sure brakes are properly bled?

Get yourself a friend and bleed them again.

 

[058hammer]

That's the first places I'd start.

 

[lindstromjd]

Vacuum has nothing to do with the brake pedal going all the way to the floor. Either you have air in your system, or your back brakes are locked up. In the 4 trucks I've had, 3 of them have had locked rear brakes that needed replacing. After replacing the back brakes, no more brake problem.

 

[rattleonby]

Ditto on the above suggestions also. I had a similar problem with my truck having the brake pedal going almost all the way to the floor before it started braking. I crawled under and put the rear end in the air on jackstands to find they were way out of adjustment when i bought it. Bleed it first and make sure your calipers arent seizing up and thoroughly check your entire system. I have a feeling you either have air in your system and/or your rear brakes are way out of adjustment.

 

[ZachStack]

i bought the truck off my step dad and he had replaced almost the entire brake system from booster, master, brake lines, calipers, pads, disks, wheel cylinders, shoes, drums, and the hardware...my first thought was that he didnt either adjust the rear correctly or just didnt bleed them all the way. thanks for the advise and help!

 

[79jasper]

My 94 was the same way with the brakes since I've owned it. (Almost 3 years but hadn't been driven since the first year until here recently) Anyways I replaced the master cylinder a few months back, then adjusted the rears, then flushed and bled all the lines a few weeks ago. Brakes worked great until I got back from a road trip. I'm guessing the rears broke in so to speak. (From being glazed over) So now I need to readjust them and replace the shoes.

Don't forget the bleeder on the rabs valve.
And also, normal speed bleeders will NOT work on the front. They're not long enough. (Ask me how I know )

 

[SearsMech]

Ther's a thread over at FTE about the rear ABS controller/modulator.

http://www.ford-trucks.com/forums/783071-brake-fade-soft-pedal-rabs-bypass-repair-92-f-250-a.html

 

[ZachStack]

i am going to try this in the morning.

 

[G. Mann]

Just did a brake job on my 87 F250, 4x4 two weeks ago. Came time to bleed the system and no helper to be found, so I picked up a used cheap electric fuel pump out of my "spare parts bin" and some clear plastic tubing and did this:

Put the tubing on the "intake side" of the fuel pump on the bleeder valve, put the tubing on the "output side" into a clean soda bottle, took the cap off the master cylinder and set it on loose.

Applied 12 volts to the pump and used the pump to pump the old brake fluid out of the line and master cylinder, into the soda bottle. Closed the bleed screw, went to the other side, repeated the same proceedure. At this point, master cylinder is empty, the tired and dirty brake fluid is pumped out of the system.. moved to the rear, longest line first, same thing, then the "short side" line.

Now to fill the brake system and bleed it.. one man style... reversed the pump.. dropped the "intake side" tubing into a clean bottle of brake fluid, hooked the "output side" tube to the bleed valve, Opened the valve, applied 12 volts to pump. Watched the fluid pumped from the bottom up to the master cylinder, nice solid supply, no air bubbles going in to the bleed port. Watched the master cylinder and when the bottom of the master cylinder tank had about 1/4 inch of new brake fluid in it, I closed the bleed valve and unplugged the pump. Move to other side, repeat.. add another 1/4 inch of fluid pumped from the bottom up to the master cylinder tank, close bleed valve, move to back wheels, do same thing.. pump from the bottom up, longest line first.

Don't try to fill the master from the bottom, soon as you have fluid covering the port + a little, you are good. When you get all 4 wheels bled from the bottom, close the last bleed screw, unplug the pump, fill the master cylinder to the required level.

Now, get in and pump your brake peddle a few times. It should feel nice and solid. [manually adjust the rear shoes, I took the automatic adjusters out, I'll adjust them myself]

By pumping fluid from the bottom, the air in the system is pushed UP, which is how air wants to go. One man brake bleed, took all of about 10 minutes... and no mess. The clear line lets you see what you are pumping out.. and pumping in. Any low pressure electric fuel pump will work. About 4 ft of clear plastic hose from the hardware store..

Hope this helps

 

[79jasper]

I would do like G. Mann suggested. Sounds great.
Bleed and adjust before condemning the Rabs valve.

To me, the rabs valve can't really cause the symptoms you described. (Albeit not impossible though)

 

[ah1988ford]

Dont forget to bleed the little brake distributor under the drivers side on the frame rail its a bit hidden.

 

[79jasper]

Dont forget to bleed the little brake distributor under the drivers side on the frame rail its a bit hidden.

Rabs valve.