Spongy Brakes?? Tried everything!!

[RACERGIRL]

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]

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

 

[Sevan]

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]

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

 

[RACERGIRL]

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

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]

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.

Did you bench bleed the MC before installing the lines?

 

[RACERGIRL]

Did you bench bleed the MC before installing the lines?

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]

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]

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.

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.