Bleeding Master cylinder

[Ralph]

I have been restoring my 73cuda and had the power booster restored and will use the existing brake cylinder and proportioning valve that was checked out as well.

How is the best way to bleed the master cylinder. I understand that it is bench bleed ? The brake lines and all the brake components are new.

Any help would be appreciated.

Thanks to all

Ralph

 

[moparleo]

Are you re using your old master cylinder ?

 

[NoCar340]

Get a couple of short lines that thread into the cylinder where the brake lines would be. Install them, then bend them so that the open ends empty back into the reservoir chambers below the level of the fluid. Mount the cylinder to the car, fill it with fluid and pump slowly until no bubbles come out of the fluid being squirted back into the master cylinder. Go easy on the pedal, light on pressure and with a slow foot, because with no hydraulic resistance it's easy to push and you don't want to shoot brake fluid everywhere. If you don't have a helper to watch, just get out and look after every other pump to check for bubbles. No more bubbles means you're done. You can then install your brake lines and proceed to bleed the car. In case you don't know, and for anyone else reading that's not aware, the proper sequence when bleeding all four brakes is passenger rear, driver rear, passenger front, and driver front.

 

[moparleo]

That is the correct sequence for non abs brake systems. If m/c is old, replace with new m/c. Do not use a rebuilt. Use only brake fluid from a sealed container. Use a high quality ,name brand and DOT 3 spec fluid. Most new master cylinders come with bleeder tubes for bench bleeding. Be sure to also adjust your rear brakes. Check your flexible brake lines for wear/cracks. If older than 10 years old, replace with braided lines. They are very reasonably priced and give a firmer brake pedal because the lines will not expand when braking. Remember that the braking system is the most important system on your car and you should use only new, name brand parts.
A 1 pint bottle should be all you need to flush the brake system. Brake fluid should be changed every three years due to moisture absorbed in the system. Brake fluid is hygroscopic , which means it absorbs water. Under hard braking the fluid will see over 200 degrees temp. Water boils at 212. This is what causes brake pedal fade or the pedal going to the floor. Since water boils at a temperature lower than the brake fluid reaches, it will boil/evaporate causing the pedal to drop. Could be very dangerous.

Here is a link to brake fluid info:
http://www.stoptech.com/technical-support/technical-white-papers/brake-fluid

 

[Ralph]

moparleo, my car has a new master cylinder and has checked out good by a mopar brake specialist, he also rebuilt the power booster and checked out the proportioning valve. All brake lines, disc's pads, cylinders, springs, rotors are new. I used the braided lines in the front. Redid all the emergency brake stuff as well. This will be a good driver for me so I need it to brake well.

nocar340, thank for the information on how to do this on the car.

Thanks to all and the fast turnaround on the info

Ralph

 

[moparleo]

Excellent. The info was also for any members that were reading your post.

 

[ramenth]

As has been said, slowly and light pressure. Push too much and you'll push pass the cups in the master. Not good.

 

[bc3j]

I have used a mc brake bleeder kit but sealed the threaded plastic fittings with epoxy. No tubes leading back to the mc. I then pushed slowly on the brake pedal by hand while my helper watched until there was no more air. I only hand pushed the brake pedal approximately 3/4ths of its travel. The mc was filled to little less than half. Less likely to have the brake fluid squirt out. Worked great and very easy to do. The pedal will become hard to push.

 

[js29]

I thought I would ask a question on using DOT 5 silicone brake fluid sense the system is new. it's non hydroscopic as as it is called so it's not suppose to absorb water. I was wondering if any one has had any experience doing this. or any thought's on this. I have read that car's that sit allot can benefit using it P.S. grate job on explaining the proses of the brake bleed

 

[MOPARMITCH]

I use Dot 5 silicone in all my hot rods/resto's. It is more expensive, but it is not hydroscopic, and also will not eat painted surfaces like Dot 3. I like it a lot.

 

[moparleo]

For more info on using DOT 5 on a street car, please read the link I left on post #4