cor72vette

It's 3&4 syn. Not all synthetic is 5.

Caliper 1=stock. 2=Autozone. 3=Napa. I purposely bought from a different supplier.

cor72vette

After determining the right replacement rebuilt caliper was defective, I replaced it again. Right front still had problems. Starting working backwards... replaced all the brake hoses with Crown braided lines. BINGO! That was the fix. After removing the stock lines, I could actually collapse them with a vacuum. Typical Chrysler junk. The upside of the braided lines is a nice firm pedal.

Mr.T

How can a flexible brake line cause brake bind when the temperature goes up? Brake lines are not subject to vacuum, only pressure -- I'm thinking that changing brake lines was a coincidence and something else changed to affect the symptom.

In any case, glad it's fixed

cor72vette

Easily. The rubber line gets soft and deterorates with age and heat exasperates it. You push the pedal, the line expands, you let off and it contracts not letting the brake leave the caliper as it normally would.

Mr.T

That's not the way it works. When the pedal is released the fluid has a direct path back to the brake fluid reservoir.

That's why the brake fluid level goes down as brakes wear, and why hot expanded brake fluid doesn't hold the brakes on.

cor72vette

No point debating it. That's what was happening. Youtube it. There's plenty of vids that show brake prblems caused by collapsing brake lines.

Mr.T

https://en.wikipedia.org/wiki/Master_cylinder

See the article above. Click on the "master cylinder schematic" and note the hole labeled "fluid intake and return port". This port is uncovered when the pedal is released, and covered during the first few millimeters of pedal travel.

Youtube has a lot of BS, not exactly a tech book.

ronjenx

Are you confusing synthetic DOT 3&4 with silicone DOT 5?

Mr.T

How about taking some dikes and cut the old brake hoses in a few places, look inside, and see what condition they're in. Maybe the brake hose was simply clogged up with particles that made the brake very slow to release.

Smudgeontheglass

Pressure on the line causes the line to swell, releasing the pressure causes a slight vacuum on the line which causing the old line to collapse and basically sealing in the fluid. This means that the majority of the hydraulic pressure is off of the piston, but there is still enough there to maintain contact with the rotor causing the brakes to stick.

Stretched, sagged, hot or old, the stock lines work for basic road duty but will fail on heavy duty use after a while.