My Intro/2006 Yukon Brake Issue

[6977Gregyver]

Likely the rubber brake lines are collapsing. Are they original?

Yes they are original. How would the lines collapsing cause the brakes to 'apply themselves' randomly while driving? Is the rod from the master cylinder that connects to the brake light switch and brake pedal adjustable?

 

[Fless]

I don't know about the MC rod. It may or may not be the case for yours, but the rubber brake lines have been known to get soft and collapse, not allowing the calipers to fully retract the pads after braking. Maybe heat causes an issue while you're driving, that's just a WAG to consider.

Air in the system is much more likely a problem.

 

[MassHoe04]

I have seen what @Fless has described with collapsed hoses. That happens fairly frequently on old rubber brake lines.

Are you sure the caliper pistons are moving freely?

My rear calipers were fine when I bought it. The brake pads were already worn down and really thin at the time, so it wasn't long before I did new rotors and pads.

It turned out that the brake pads had been on for so long and warn down to the metal backing, that over time corrosion build up behind the pistons. When it was running the worn pads and the pads wore down more and more, the piston was way out and only moved a small bit to apply the thin pads.

So when I put fat new pads on there, the pistons were now pushed back into the crusty part of the cylinder. First application of the brakes, the piston did push out to apply the pads to the rotor nice and hard. But... The cylinders would not move back to release at all! The rotors were smoking and glowing cherry red!!! It was new calipers for me... Luckily, there was no damage to the rotors or pads.