Did you bench bleed the new master cylinder? I would try gravity bleeding them and see if that will fix it. Basically, make sure the M/C is full, starting with the RR, loosen the bleeder and let the fluid drip into a pan for 15-20 minutes, tighten the bleeder. Watch the bleeder as the fluid drips for any bubbles. As long as there are bubbles, there is air in the system. Then go to the LR and do the same thing. Next, do the RF and then the LF. Keep an eye on the fluid level during the process and don't push on the pedal. Let us know if it works.79bird said:Ok So a while ago, as stated before,my mom made me go to the local mechanic shop to fix my brakes and told me that my proportioning valve and master were out. So i just replaced the master myself with a cheapo $25 one. Problem is that ive bleed the system for like 2 hours straight and now with the new master, the car doesn't lockup tires when i slam the brakes like it used too, and i have to push down pretty far to get the brakes going and its not very good either. Should i replace the PP valve with another one or try a different master cylinder? I think the quality of the master might be bad as well..What do you guys think? I tested the booster and it checks out and no brake fluid leaks anywhere else....Please help I know this sounds weird but I have a date with the girl i like in a few days and i dont wanna crash my firebird with her in it!!