1994 mustang gt brakes question

neonstang · Dec 26, 2014

Hi, First Merry Christmas and a happy new year to everyone. My car is a 94 mustang gt, the car is painted dark tourmaline metallic and has 18 X 9 Saleen replica wheels. The problem I have is when I lift the back of the car and let the tires spin in the air and come to a stop, the back wheels only stop for a moment then begin to move slowly with the brakes completely apply. Is this normal or there is something wrong with my brake system? Already install new master cylinder, new brake calipers in the back, PBR calipers in front, russell streel legal brake lines, new rear center brake hose and drilled and slotted rotors. Right now the engine is stock, but the transmission(AODE) has been rebuild with upgraded parts like transgo shift kit, mechanical diode, hardened intermediate shaft and many other things. The differential has 3.73 gears and has been completely rebuild including the posi unit. For the engine, since this is my daily driver and don't have many money to spend, I already has to upgrade it, Explorer heads and intake, intake elbow, Edelbrock 65mm throtle body, c&L intake calibrated for 24pounds injectors, 24 pounds injectors, 1.7 cobra roller rockers and an adjustable fuel pressure regulator. Almost all was buy through ebay. Still need to buy bbk shorty headers, spark plug wires, gaskets, the spring kit for the heads and send the heads to the machine shop. Sorry about the long post but need you to know everything about the car so you can help me. Thank You.

Addermk2 · Dec 26, 2014

Probably still have air in your brakes. If you can't get a good bleed, you should consider having a shop do a power bleed.

mcglsr2 · Dec 26, 2014

Just making sure: when you say the brakes were applied, were you talking about pressing on the brake pedal, or pulling up the emergency brake?

Either way, the wheel should not spin with the brake applied. Depending on which brake you were applying, the cause could be different things. If it was the pedal brake, then listen to Addermk2. (This is also assuming you have good brake pads in and that they are not worn to the metal - right?)

RichV · Dec 26, 2014

How does the pedal feel? soft or firm?
Do the wheels still spin if you pump the pedal multiple times?

neonstang · Dec 26, 2014

Thank you all, I put new pads when the rotors and calipers were installed. The brake applied is the pedal and the pedal feels normal not soft or hard. The car only do this if you come to a complete stop. The tires stop completely then begin to move slow with the pedal applied, but there is no change in the pedal feel. If I pump the pedal you can feel the calipers apply and the tires stop, then do the same thing they begin to move slowly again.

RichV · Dec 26, 2014

My guess would be the booster, MC, or a possible ABS issue.

Could definitely be air in the lines as well. I would do a complete brake system flush with new fluid, and start there.

How did you bleed the system after you replaced the rear calipers?

brendancunningham · Dec 26, 2014

did you bench bleed the master?

neonstang · Dec 26, 2014

Yes the master was bench bleed. We bleed the brakes until only fluid was coming from the hose and do the right rear tire, left rear tire, right front tire and left front tire. RichV, maybe you have a point with the ABS issue, because the ABS unit was disconnected(fuse removed) long ago because it was giving me issues. When you try to stop slowly in traffic the calipers acts like they are supposed to do when you are doing an emergency stop and make the car hard to stop because of all the apply and release the calipers were doing. When we bleed the brakes the ABS unit was disconnected but we did not see any more air coming from the hose. Maybe it can be the brand of fluid we use. It was DOT 3. What brand of brake fluid do you recommend. Thank You.

Addermk2 · Dec 27, 2014

neonstang said:
Yes the master was bench bleed. We bleed the brakes until only fluid was coming from the hose and do the right rear tire, left rear tire, right front tire and left front tire. RichV, maybe you have a point with the ABS issue, because the ABS unit was disconnected(fuse removed) long ago because it was giving me issues. When you try to stop slowly in traffic the calipers acts like they are supposed to do when you are doing an emergency stop and make the car hard to stop because of all the apply and release the calipers were doing. When we bleed the brakes the ABS unit was disconnected but we did not see any more air coming from the hose. Maybe it can be the brand of fluid we use. It was DOT 3. What brand of brake fluid do you recommend. Thank You.

brand of brake fluid in a street car is basically irrelevant. If you have a bad ABS module, just delete it. You've probably got air trapped inside it from changing the master. You are never supposed to pump air through an ABS unit. You should have gravity bled the lines right to the ABS pump itself, so that air transmission would be minimal.

neonstang · Dec 29, 2014

Sorry for the delay, but had problems with my internet connection. Thank you all, I will try to find the ABS unit and then take my car to a mechanic for the unit to be professionally installed and bleed. For now the car is been painted and cannot used it until september of next year. Happy Holidays for everyone in the forum.