bigearl56

Took the ‘66 out for cruise a couple weeks ago for the first time this year. All going smooth, got to the second intersection and she stopped beautifully. Pulled away and had no power. Pushed in the clutch and car came to quick stop. Back in low and barely pulled off then broke free. Made a u-turn heading back to the barn with a burning smell coming in the cabin. Got her up on the lift and all four wheel would barely turn by hand. Let it set for a day and they freed up. Did another road test and she did the same thing. I’m thinking deteriorated rubber brake lines so I now have four American made new ones which I plan to install this week. Anyone’s thoughts on this problem is greatly appreciated.
Earl

Powershift

Master cylinders have a pressure release port in the bottom that relieves the line pressure when you take your foot off the brake pedal. If fluid is old or has some solids/deterioration this could plug. Or the o-rings in the MC are deteriorated and sticking. Since fluid will be changed during brake bleeding things may clear up on their own after you replace the hoses. If not, a MC rebuild may be needed.

Larry

Pop Chevy

All four ! Could be the lines, but I would be taking a close look at the master and the pedal itself.

Bluestripe67

After you do the repairs, drive the car a lot more often. Sitting for extended periods of time doesn't do it any good. Dennis

65GGvert

All four didn't suddenly go bad at once. Your problem will be around the master cylinder.

Aflyer

I agree with others, start with Master Cylinder.
I completely rebuilt my brake system about 5 years ago, and converted to silicone brake fluid. I did it because I got tired of the maintenance, required by lack of use.
If you drive them often, and change out the fluid often all is good, but if they sit in the garages more than they are driven, you will have issues as you are seeing.
Aflyer

63 340HP

Replace the flex lines, but moisture in brake fluid can swell and expand to lock the brakes.

I worked on a Pantera for an owner who I learned lived at the beach. He let the car sit for a year or more after buying it at an action and trailering it to Willow Springs. He achieved about two laps when the brakes froze up. He called a local shop, and they referred me as I lived close to the track. The brakes had partially released by the time I arrived, but the owner was hammering the brake pedal up and down the entry road to the track, with more lock up. Moisture turned to steam in the calipers, and the line pressure exceeded what the master cylinder would build to release the check valves. Opening the caliper bleed valves resulted in fluid spitting ten feet. We bled the fluid, but the driver's pedal hammering with the heat and pressure had already warped the calipers. The car sat in the shop that referred me for three weeks as new brake parts trickled in.

GTOguy

Good advice by all, but I too would start at the MC. Usually one or at most two hoses will go bad during an event, not all 4. I'm betting the MC is holding pressure.

bigearl56

Well I know we hate it when someone ask for help and never gets back when the problem is corrected. Let me begin by thanking all who offered solutions to my braking problems. As it turns out the MC was defective. I sent it out to White Post for sleving and rebuild. All four calipers were filled with mud and some of the inner passage ways were blocked. Thank goodness the calipers were SS lined so they cleaned up nice. I also rebuilt the parking brake and as we all know that is an adventure all it’s own. Did the final bleed this AM and we have a solid pedal and no leaks. So after several months and COVID-19 the ‘66 is back on the road.
Stay Safe
Earl