Fox Brakes - Can't lock up if I tried

[Zoom50]

I am thinking its time to address my poor braking with my 91 GT. I can press the pedal as hard as I can and the car will still not lock up the tires. I have owned a fox before and know their brakes suck, but these are not even to that level. I have not tried to diagnose the problem yet, but I am assuming that it is related to 1 or more of the following:

1. Calipers need replaced
2. Issue with the pads
3. Master cylinder needs replaced
4. Brake booster needs replaced
5. Brake lines need replaced

Any thoughts on what to look out for before I start replacing crap that does not need replaced?

[PaxtonShelby]

Have you flushed the brake system with fresh fluid and then bled the system? If not...start there.

[mustang50lx]

Don't forget also that there is a big difference in how hard you are pushing the pedal between just going out and trying to lock the brakes up and how hard you push in a panic situation like if a deer runs out. When I was working in a bodyshop we had a Lumina come in with a twist on brake booster that the lady actually pushed off the firewall she hit the brakes so hard and still wrecked. Is the pedal high and does it feel okay just driving around? Wheel cylinders can freeze / rust and quit working. I would lift it up and make sure all 4 wheels are actually working.