My car suffers from insufficient braking. It stops, just not very well. In a panic stop I am unable to make the car skid (lock up the wheels) at any speed. The car does NOT have ABS (although I wish it did). The original rotors showed signs of excessive wear such that the contact surface with the pads was below the original face of the rotors by more than a few hundredths of an inch. So I replaced all 4 rotors & pads front & rear. I replaced the fronts with slotted rotors in an attempt to improve wet braking. With the original OE rotors there were times in the rain when I had absolutely NO brakes. I think the slots have fixed this situation. But still I can't make the car skid. Something is still wrong.
I've checked all the plumbing front to back & top to bottom for leaks & can find no external leaks. If there are internal leaks in the Master Cylinder or Booster they're not visible.
The pedal is NOT spongy. When I press on the brakes the pressure holds fine. The pedal NEVER goes to the floor. Even when I had no brakes in the rain the pedal held firm, the car just didn't stop (it actually felt like it accelerated when I slammed on the brakes. Yikes.). If I held the brakes on periodically in the rain the rotors stayed dry enough that I had brakes, but it meant riding the brakes, a situation I find very unnerving.
I ran a diagnostic for the booster which claims the booster is working A-OK. I had a booster fail on my truck a number of years ago & I could spot the problem when I first started it up in the morning. I would step on the brake before starting the truck & when the engine vacuum was applied to the booster the brake pedal would drop. This car shows no signs of the pedal falling under any circumstances so I'm not convinced that the booster is the problem.
I can't locate the proportioning valve. I'm sure there's one in there somewhere but it's not obvious. I'm not sure how to reset it even if I knew where it was.
So I'm stumped. Any suggestions appreciated.
Friday, November 17th, 2017 AT 7:22 PM