What could be wrong with my brakes?

[roadrunner19va]

I have a 1991 mustang 5.0. The brakes on this thing suck. I put new pads, rotors, and bearings on it in order to pass Md. inspection. This car will not lock the brakes up. I can push it as hard as I can and the car will not lock up the brakes. Also the pedal feels really stiff. I figure that is from the stainless lines that it has. This thing almost scares me because the stopping distance sucks. If I had to stop fast I would be screwed. I had a 1993 before this one and the brakes were way better. I do not want to start throwing parts on it until it fixes it. Thanks in advance for your help.

 

[86bluecobra]

perhaps your power assist is not working. Make sure the vacuum line to the brake line is not damaged and see if there is even vacuum at the tee where the line comes off.

 

[Roland69]

are they bled good

are the rear adjusted right...both should just have a touch of drag

also check what 86bluecobra said.....

 

[adversary]

I dont suppose you have a picture of where that vacuum line is do you? I'm having the same exact problem on the same exact year car! thanks guys!

 

[GearHd6]

The vacuum line comes out of the booster and goes to the main vacuum junction mounted to the firewall.

 

[jrichker]

I dont suppose you have a picture of where that vacuum line is do you? I'm having the same exact problem on the same exact year car! thanks guys!

Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel pump, alternator, ignition & A/C wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Computer,. actuator & sensor wiring
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Fuse panel layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Vacuum routing
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

Check the power brake booster rubber grommet where the vacuum line fits. They are known to leak. To check the booster, start the car and run the engine for 30 seconds at 1000 RPM. This builds up vacuum for the power brakes. Cut the engine off, and press on the brakes. Each time you press on the brake pedal, you should have a harder pedal, and it will travel less before it gets hard.

I would recomend that you use a vacuum gauge to check the vacuum. You should have 14"-18" of vacuum at 625-750 RPM and 18"-21" of vacuum at 1000 RPM.

 

[Drinknbuddy]

I had the same problem... it was the brake booster not getting any vacuum. now car stops like a champ.

 

[Mustang5L5]

Have you bled the brakes? If the fluid is dark colored, that could be your reason right there

 

[dec322]

I had the same problem on my first car (super cool 84 Ford LTD). It was the brake booster.....I had to replace it.