Spongy Brakes?? Tried everything!!

R

RACERGIRL

New Member

Aug 30, 2005

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Aug 30, 2005

#1

• Aug 30, 2005

• #1

Ok here's the situation- I road race my mustang and when I pulled it out of storage to run this year the brakes were spongier than normal. First we flushed whole system with Wilwood fluid. nothing-- We thought booster because the master wasn't leaking. Changed it and it was worse with the auto parts store booter than the original. So we changed the master with a rebuilt auto parts store one. Pedal still spongy.
Then we replaced the master with one we had off of an 89, and it improved it a little, but still spongy. When the car is started it will stop the car but the pedal will eventually fall 2-3" instead of staying hard.
Any ideas??

It has no bubbles- braided lines- no collapsed hard lines and it's losing no fluid.
We're completely stumped.

 

88GT17MA

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Nov 1, 2004

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Aug 30, 2005

#2

• Aug 30, 2005

• #2

need more info on your brake setup. 4 wheel disk? what brakes? drum?

 

S

Sevan

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Dec 4, 2001

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IL

Aug 30, 2005

#3

• Aug 30, 2005

• #3

hmmm. Do you have 4 wheel disk? If so, is your master big enough, like the 1993 Cobra's master? What condition are your rotors, pads and calipers? Are you using stock brakes? Or you can use Wilwood Proportioning Valves


http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=1179&prmenbr=361

 

garystocker

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Jan 2, 2005

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New Jersey

Aug 30, 2005

#4

• Aug 30, 2005

• #4

wheel cylinders

pull the boot on the wheel cylinder. It can slow- leak past the piston but stay in the boot keeping a dry appearence and a full fluid level.

If fluid drips from the wheel cylinder (and I assume you have rear drums) replace both wheel cylinders.

Let us know how you make out...

Gary

 

R

RACERGIRL

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Aug 30, 2005

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Aug 30, 2005

#5

• Aug 30, 2005

• #5

88GT17MA said:

need more info on your brake setup. 4 wheel disk? what brakes? drum?

Click to expand...

73mm MarkVII upgrade in the front and the baer disc touring kit in the back. Baer states that the bigger master is not needed. Upon pushing the pedal down it stays full fluid in the reservoir.
SSBC proportioning valve, and fresh slotted rotors with Black cmpd Baer pads.

 

tunedin302

I AM the law!!!

Jul 29, 2004

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Pennsylvania

Aug 30, 2005

#6

• Aug 30, 2005

• #6

RACERGIRL said:

73mm MarkVII upgrade in the front and the baer disc touring kit in the back. Baer states that the bigger master is not needed. Upon pushing the pedal down it stays full fluid in the reservoir.

Click to expand...

Did you bench bleed the MC before installing the lines?

 

R

RACERGIRL

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Aug 30, 2005

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#7

• Aug 30, 2005

• #7

tunedin302 said:

Did you bench bleed the MC before installing the lines?

Click to expand...

Yes but we used our fingers then recapped with the plastic plugs when we mounted it. Is it possible that there's still air in the master if we pushed 4 cans of fluid bubbless through the whole system? I didn't think it could stay in there.

 

garystocker

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Aug 30, 2005

#8

• Aug 30, 2005

• #8

Master must be bench bled free of bubbles prior to bleeding of entire system. The brake pedal does not push the piston as much as you can on a bench with a dowl.
Bleeding kit has hoses which recirculate the fluid and you pump with a dowl and tap the side with a tool to help dislodge the bubbles.

 

tunedin302

I AM the law!!!

Jul 29, 2004

1,251

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36

Pennsylvania

Aug 30, 2005

#9

• Aug 30, 2005

• #9

garystocker said:

Master must be bench bled free of bubbles prior to bleeding of entire system. The brake pedal does not push the piston as much as you can on a bench with a dowl.
Bleeding kit has hoses which recirculate the fluid and you pump with a dowl and tap the side with a tool to help dislodge the bubbles.

Click to expand...

Take the MC out of the car to bench bleed it. I used my old steel brake lines, put them into the MC and then used plastic lines off them to bench bleed it. Good luck.