I will close out my related question once I finish the job. Quick question. Looks like a defective caliper can cause excessive brake travel. How in the world does it do this? In my minds eye I think of a hydraulic piston at the end of a sealed brake line. Its probably obvious but, where does excessive travel come from?
thanks, John

 

John, Need a little more info. How long since you've been able to bleed the brake lines or completely change out the brake fluid?

 

Quick answer. It comes from air bubbles in cool lines. It comes from water vapor in hot lines. As redline says neither exists in a properly bled system with fresh fluid.

 

Ah! Trick question? lol...

 

Hi Thanks for the answer. Here's the thing:

I've been chasing low brake pedal, extra effort needed to engage hard. Completely changed the brake fluid. After extensive bleeding, got her back to where she was before I started to fix the low pedal.

Finally hit the end of my abilities - took her to a mechanic. He test drove, concluded that I either had binding caliper pins or a bad caliper. I lubed the pin of driver side rear - it made a big difference for the better. As I lubed the pin I checked the pad, kind of low going to replace. But here's the thing. I had been getting an intermittent squeal from this brake, it comes and goes.

When I looked at the rotor - I noticed rust on the inside 1/2 of the rotor. Here's what I mean: Let's assume the rotor surface is 6 inch diameter inner edge, to 10 inches outer edge. Imaging a 8 inch concentric circle on top of the rotor - its all rust. The outer 2 inches are polished normal looking. Other 3 rotors have no rust. I am going to replace this caliper.

As I looked into the root cause of the extra brake travel / low brake everything including this mechanic says defective caliper can be a cause. I posted this question because I'm having trouble picturing what about a defective caliper could cause a low pedal. Its probably something obvious, but as I picture the caliper in my minds eye it's just a hydraulic piston at the end of a sealed brake line. What could go wrong to increase brake pedal travel from a defective caliper? Is it the piston retracting too much or unevenly?

Please let me know what you think, I'd love to learn.

Going to pick up the new caliper tomorrow, put new pads on and see if I can track down a new rotor (no one seems to turn rotors around here anymore). Will let you know how it goes. Right now I'm just wondering about the question: How can a defective brake caliper cause low pedal?

Thanks,

John

 

You have a cocked piston or the pad is not seated in place.
Lucky for you it's releasing, well, sometimes it's not.
The new caliber will surely help, but have a look at the pad when you take it out, notice if it's twisted in the framing of the bracket or some sort of debris keeping it from seating.

 

Wayne, I've gotta work around an upcoming snow storm, but I'll let you know theyblook like when I'm done.

Sure did want to thank you though. I appreciate it.


John