Hard brake pedal

None2Slow

Registered User
I have done the swap from abs to standard power assist. Here is a past link where I posted about this problem. http://www.sccoa.com/forums/showthread.php?t=87412
I have since put in a MC from a 93 Crown Vic that I bought new, not rebuilt. I still have a hard pedal. When I bleed the brakes, I start with the pass rear first. The first couple times its soft, then firms up, then pretty much the pedal is hard whenever I pump the brakes. Open the bleeder and the pedal goes to the floor. Close it and pump it maybe twice and the pedal is very hard. Open the bleeder and goes down again. Is it possible that I have a bad caliper? The reason I did the swap is that I had a hard pedal and I bought an accumulator ball and that didn't fix it. Didn't want to throw a bunch of money and the swap is so simple and cheap, why not. Now I'm wondering if it was necessary. Any place to look would be a help.
 
Do you have a vacuum source for the vacuum assist plenum on the new brake master cylinder? You did get the vacuum assist plenum didn't you?
 
I have the vacuum hose hooked to the T on the back of the engine near the firewall. That shouldn't make a difference when bleeding brakes with the car off should it?
 
If there is no vacuum, you have no assist. With no assist, the pedal will be hard. I don't know what T you are talking about, but if that T doesn't see Vacuum when the engine is on boost, you won't get any assist.

Make sure any place that you take vacuum off of is connected to the intake plenum after the throttle body, but ahead of the blower inlet.

If you get assist when the engine is at idle, but loose it immediately after you shut the car off, either there is a problem in the master cylinder booster (it's not holding vacuum) or there is some component missing that is normally on the crown vic (some sort of oneway valve on the vacuum line?)
 
I'm wondering if its more a problem with a caliper than anything else. The pedal feels exactly like it did before I did the swap. At the time I was driving truck across country and had very little time to drive the car. It would sit for 2, 3 or ever a month at a time. I would drive it to work, let it sit, then when I would get back in I would drive it home and it would again sit for 2-3 days. Then back to work. Maybe I should just get it up and pull the wheels and see if the calipers are nnot sliding on the pins. Anybody think this may be the problem?
 
If there is no vacuum, you have no assist. With no assist, the pedal will be hard. I don't know what T you are talking about, but if that T doesn't see Vacuum when the engine is on boost, you won't get any assist.

Make sure any place that you take vacuum off of is connected to the intake plenum after the throttle body, but ahead of the blower inlet.

If you get assist when the engine is at idle, but loose it immediately after you shut the car off, either there is a problem in the master cylinder booster (it's not holding vacuum) or there is some component missing that is normally on the crown vic (some sort of oneway valve on the vacuum line?)



The T is at the firewall just behind the SC and it feeds off the intake just after the throttle body. I have No assist at any time. I have a hard pedal when I bleed the brakes. After releasing the bleeder screw and the pedal goes to the floor, I pump it back up and at maybe 2 pumps, the pedal is hard again, not firm, but hard and barely moves. Today I pulled the front calipers off and greased the sliders and the caliper brackets where the pads slide. It seemed to make a bit of difference. Maybe tomorrow I will try to get the rears done and see if that takes care of it. Other wise I don't know what to do next. Maybe start replacing calipers?
 
Even with stuck calipers, you should be able to notice if there is any assist. My gut is telling me your master cylinder isn't holding a vacuum.
 
Been busy with life and all, but I am still in the same spot with the SC. After doing the swap, I installed a longer "bolt" into the end of the push rod to lengthen it. I ground the head down to a round nub as the original is. Would a push rod thats to long cause the pedal to stay firm and maybe not release? I have been driving my 99F350 with the 7.3 power stroke daily, and with diesel now at $3.50, about $.45 gallon more than premium, I need to get this running. Plus the stereo is SOOOO much better.
 
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