For the past month, I've noticed that the brake pedal in my car is much softer than usual, not at all as firm as it normally is (or was), and that I'm having to depress the pedal further to get the car to stop.
All rotors and brake pads have been replaced within the past three years, and I've taken it to three separate auto shops who cannot find anything wrong with the braking system, or at least nothing that's apparent to them.
So my question is: Where would you look/what would you try to do in this situation when three separate routine brake inspections have yielded no results?
My car has 147000 miles.
My car has an automatic transmission.
First, I would road test the vehicle to verify there is a problem. Then I would check the parking brake is adjusted up tight. A loose adjusted parking brake means the rear brakes are out of adjustment. The parking brake should start to engage after the third or forth click when lifting handle slowly.
I would then remove all four wheels and check the brakes for problems with the brake lines, caliper slides, rotors, calipers and pads. Then remove rear drums and inspect the rear brakes for problems with the brake shoes, springs, adjusters and wheel cylinders. Once a full inspection of the entire system is done, if no problems are found, then I would check the brakes for air in the system by bleeding them out. If problem continues, then check the brake master cylinder and booster along with the brake pedal linkage. If you need help pinpointing the problem, a qualified professional from YourMechanic can come to your location to diagnose the brake system and proceed with the correct fix.