Lexus082

I have a 94 sc400 with about 300,000 miles on it. It seems that my brakes are getting slowly worse over time. I have new pads and rotors all around. When I apply the brake the pedal to stop it travels quite far (a few inches). It never goes all the way to the floor. On a new car you barely touch the brake pedal and you can feel the strong bite. My car you push the brake pedal half way down to the floor and it has a very loose bite. If i lift up a hair on the brake pedal the brakes pretty much release and the car will start to go forward. I'm almost certain there is no air in the system and the fluid has been changed every two years. I have no idea what is causing this problem, cause I've never encountered this before. I tested the brake booster by pumping the brakes and the pedal gets firmer. Could the master cylinder be failing or could the brake booster be bad? It just doesn't seem like I have alot of hydraulic pressure behind those pads. Could the old rubber brake lines contribute to this problem I'm having. I tried installing steel braided lines but they wouldn't fit my car.

SChema

iTrader: (2)

Look into your initial thought of the booster and master. Sounds to me the master is bypassing pressure causing low pressure at the corners. That is if you can insure you're not loosing any fluid anywhere in the system.

It doesn't hurt to re-bleed the system as it costs only a bottle of fluid. That would be the cheapest place to start when trying to figure this out.

scfou

iTrader: (3)

Definitely go the cheaper route first and do a good job bleeding it with 2 guys. If you get the same results definitely replace the brake master cylinder immediately as this may be a warning indicator of total failure soon to come. The brake booster may need to be replaced as well cause we are talking 300k miles on your sc.