brake problem-master cylinder maybe?

[dondiesel444]

here are the symptoms: when driving, I apply the brakes and the pedal is soft and not much braking, so I let off the pedal then push it again and then the pedal is firm and good braking. and when sitting in the X at a stop, if I push the pedal down I can feel it sink or drop a little, sometimes.

is this the master cylinder? how much am I looking at to replace it?

oh yeah I put new pads and rotors on all 4 wheels a few months back, so they are like new.

 

[unclemeat]

If it is the master cylinder when you apply pressure the pedal go to the floor. I would check the vacuum assist, and fluid. You may have a vacuum leak or air in the line.

 

[old mechanic]

Sounds like the master cylinder. How were the brakes before you put the pads & rotors on? You could have a bad caliper or you could have gotten some air in the lines. Did you check to see if your losing brake fluid?

 

[G-rigged]

if its the master cylinder your pedal will go down constantly and not stop and get firm. Sounds like you have air in your lines.

 

[dondiesel444]

the pads/rotors were shot before I replaced them, but the pedal didn't do this. I replaced the pads/rotors afew months ago but the pedal just got soft recently. I don't know how air could've got in the lines, I should check to see if any of my brake lines are leaking b/c my X is kinda rusty underneth...

 

[Ford_Racing_Guy]

sounds like the master cylinder to me

 

[Mendonca00]

If the brake pedal is pulsating like mine was, then its you VSS.

 

[jimbo74]

to me, it sounds liek you need to have the system bled...... and if you have 4 wheel abs, some pulsating pedal is normal..... i would rule out that there is air in the line by bleeding prior to assuming its the MC

 

[dondiesel444]

I guess I'll try to bleed the system and see if it helps, I am gonna have a hard time I think b/c the bleeder screws look pretty ruted, if I break one I an screwed...

 

[JimT]

I have a '91 Explorer with similar soft brakes. Bleed, bleed, bleed, pump, pump, pump, Brakes are still soft.

This is all after changing the master cylinder, both calipers, and front brake lines.

So....how do you "check/test" the booster and vacuum lines, and how in the hell does an average human with tools bleed the rabs box!!! My ABS box is located on the driver's frame but directly under the drivers seat. It appears that I'd have to drop a bunch of stuff to get to it.

Also who has the scoop on the rear disk conversion and the rabs disconnect plan?

Please email/copy paste me directly if you could.

Thanks

Jim Tallant
skyepuppie@aol.com