Brakes dragging/wheels locking

[TimBird]

I️ have a 1957 Tbird and the last two times we’ve taken I️t out to drive, the wheels have locked up after parking the car and then starting the car up to drive away. I️t seemed like the brakes would slowly start to rub and there was a smell of burning metal and then they completely locked after stopping. I️ was able to drive through I️t at first, not knowing what I️t was and there was smoke coming from all four wheels. After letting the car sit for a few hours, the problem went away only to re-occur the next time I️ drove I️t a few days later. Is I️t the master cylinder? A clog in the in the brake line? Please help

[Yadkin]

You may have water in your brake lines that expands when hot. Although there is no scheduled maintenance to change out brake fluid for these cars, there is for many European cars, and it makes sense because DOT3 fluid absorbs moisture over time. I would change out the fluid and see if that works.

Buy a quart bottle of fresh DOT3. Use a turkey baster and remove what you can out of the master cylinder reservoir, then fill it with fresh fluid. Then bleed the right rear brake until you see fresh fluid. Keep an eye on the master and keep it filled. Then bleed the rear drivers side, followed by right passenger, and finally the left passenger. Each time bleed until you see fresh fluid.

[TimBird]

Thanks! I’ll give that a try. I’ll let you know how I️t works

[TimBird]

I got back from the fire station today and went through the process of bleeding the brakes. It went well and I drove it around and the brakes seemed spongy and weak at first but then they seemed to be working great. I went to pick up my son from school and sat in stop and go traffic and the engine got very hot, temp gauge near “H” and the brakes started locking up again. Let the car sit for a few hours and checked again and they were working great. Then I went to pull it into the garage and they were locked up again. This time I noticed the brake lights were on and it clicked that the pedal seems to be stuck down and that’s why the brake lights are on. The lights had been staying on sometimes through this brake issue but I thought they were tail lights and there was a short and it was a coincidence. Now I think the two are related. Any help here?

[Yadkin]

I don't believe in coincidences. The older Fords used a pressure switch teed into the hydraulic brake line, so this is telling me that your master cylinder is, somehow, building pressure an not releasing it.

From the factory these came with a single master and drum brakes at all four corners. Good and proper modifications include conversion to a dual master, and converting the fronts to disc brakes. Once discs are used a proportioning valve should be installed. Another good mod is eliminating the hydraulic switch and using a mechanical one.

You have an issue somewhere in this system and it would be helpful to know more of what you actually have installed.

At the least you are looking at replacing a defective master. Since you need to do that, it is a good opportunity to consider upgrading the system.

[TimBird]

Thanks for the help. After some trouble shooting, I’ve decided to go with a dual master cylinder. As I do not have the ability to add additional brake lines to the system, I am having it done by a local guy that specializes in classic cars. I’m a little disappointed I couldn’t fix this myself but I like to know that when I drive my kids around the brakes work properly. I appreciate the help. When I get it back I’ll be cleaning up the undercarriage and trying to make it look good.

[paul2748]

Sounds like the master cylinder is not working properly. Possible dirt in the relief
hole not allowing for the fluid to return when the brake is released. There is a little hole in the bottom of the master.

Another think that could cause what you are experiencing is not enough gap between the rod and the master cylinder. When the fluid gets hot, it expands closing the gap and not allowing for fluid return.

The above is if all four wheels are hanging up. If it's only one or two, check the flex lines. They can go bad internally and not release fluid when the brakes are released. Since there is only one flex line to the rear, a bad one would effect both rear brakes.