11

I have been working on a 1999 Buick Century Custom that had rusted brake lines. I get strange pedal feel that I will attempt to describe:

  • From 0% to about 15% depression, there is resistance and most braking force is generated

  • From about 15% to about 70% depression, there is less resistance and no braking force is generated

  • From about 70% onwards, brakes feel normal

I am looking for insight into the cause as well as a solution. On this car, the two rear lines each have a floating portioning valve (Dorman 905-952). This car has ABS, front discs and rear drums. Recently I changed all brake lines and replaced one portioning valve (it had been deleted by the previous owner). I have bled twice (RR, RL, FR, FL). When I bled, it was not level (sitting on a jack with tires off).

I have checked for leaks on the new lines, no leaks found. The wheel cylinders don't leak. I want to also say, the car seems to stop just fine every time (just requires a lot of travel).

Alex Hirzel
  • 328
  • 2
  • 9

2 Answers2

2

It turned out the drum adjusters were set wrong and seized. As near as I can reason, what I was feeling at first was the fluid back-pressure needed to overcome the portioning valves (and some braking force from the discs). Then the "dead zone" was fighting the drum's wheel cylinder return spring after the portioning valves had opened. The final stage of normal braking occurred after the drum wheel cylinders expanded fully.

Thanks everyone for your answers! I hope this helps someone in the future.

Alex Hirzel
  • 328
  • 2
  • 9
-1

Master cylinder is going out of business. Make sure to replace it and bench bleed it before re-installing.

race fever
  • 3,353
  • 13
  • 23