jacked 5.0 brakes

[mynephratieri]

help! my brakes are rock solid and dont want to stop.new pads,swapped calipers from another car,slotted new rotors,swapped the master cylinder and brake booster and no change.i can slam on them and barely stop.i had a shop do a rear brake job also.yes has all been bled as well.it still is just as hard to stop as before all changes.also the e brake can be yanked at any speed with no results,just the brake light.what is up????????

 

[Mustang78]

sounds like the rear brakes are out of adjustment, pull the hubs off and you'll see the clicker at the bottom, turn that and test fit the hub again, if it drags slightly it's ok, thats properly adjusted, or so

~Mark~

 

[Roland69]

you can just remove the little rubber plug on the inner side of the backing plate and adjust the rear brakes that way...you want it to just slightly have drag and an even amount on both sides. But as for your question I would lean towards a Vacuum problem perhaps...I have stock brakes and can lock them up kind of easy

 

[mynephratieri]

the only vacumm goes to the booster to the intake right?i will try the adjustment part today and see if it changes anything.is there any other vac lines i should check?thanx

 

[jrichker]

Check the rubber grommet for that brake booster check valve mounts in. It is a known source of leaks. The check valve is the metal fitting on the vacuum line that comes from the vacuum distribution block.

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

 

[mynephratieri]

ok,the vac line is all good.the e brake cables are rusted to not moving.i got one broke free, working on the other.i tried the adjustment thing on both sides.totally loose ,then tighter then dragging,then full tight.nothing changed except when full tight,did not spin at all,obviously.tried driving all three times as well as spinning the tire.at 45 mph,the front can lock but not the rear.but the pedal is still so hard not even funny.my 90 vert and 91 gt both are very touchy lock up right.i swapped all components other than the lines themselves,no dice.could the ebrake lines have something to do with this?this sucks!thanx for the reponses guys,appreciate it.

 

[jrichker]

Power brake booster test:
1.) Check engine vacuum you should have 14"-18" of vacuum at 625-750 RPM, 18"-21" vacuum at 1000 RPM.
2.) Vacuum checks good, start car and run engine up to 1000 RPM for 30 seconds.
3.) Cut off the engine and then press the brake pedal 3 times. It should get harder to press and travel less each time you press it. If it doesn't, then the brake booster is suspect.

 

[mynephratieri]

the vac is good,the pedal gets harder.i also swapped the booster from my 90 vert with this one and no change to either vehicle.the booster was what the book said it could be but worked fine in the other vehicle.also when i pull off the vac line the engine wants to die so it is all good there also.crazy huh?

 

[mynephratieri]

ok,i rebled the system again,then put the rear on stands.started the car put in drive and ran it up to 35 mph while on the jack stands.i hit the brakes.my rear wheels barely slowed down!the ebrake did not do anything either.so i obviously got a problem in the rear.the rears are getting fluid,when i bled no problem,and after adjusting the rear, hard to get the drum off ,so i know the adjuster works that way.any other ideas?