Brakes

[Woodie1]

I am about to start changing out brake cylinders. Is it best to adjust the brakes after bleeding or before? I have also seen mention of using teflon tape on the bleeder screw threads, shouldn't the tapered end of the bleeder seal the system when the bleeder is screwed back in?

[solidaxle]

I have questions about your questions.


I'll assume you're having a problem with your brakes, hence changing the cylinders. Please describe your symptoms.


What year brakes are you referring to?



The tamper end of the bleeder will seal the system if not corroded or damaged. The reason for teflon or sealant is to stop the air from entering though the threads when bleeding.



It's been discussed many times with detailed instructions on here how to adjust early Ford brakes, if that is what you are working on. Try searching under the advance option.

[Woodie1]

I worked on our 1939 brakes a little last year. I had to replace 1 front wheel cylinder because of leaking & corrosion. I have since learned I should have replaced both front wheel cylinders. I pulled the rubber boot back on a rear wheel cylinder yesterday & it started to weep brake fluid. The car supposedly had all new wheel & master cylinders replaced in 2014. I believe the car sat a lot though. I have the detailed instructions for doing the brakes.

[Flathead Fever]

When we did brake jobs at work, we suctioned out the master cylinder and filled it with clean fluid and left the cap off. We opened the bleeders and let them gravity bleed while we were doing the brake job. That worked because the master cylinder was higher than the bleeders, but it won't work on an Early Ford. If you're bleeding the brakes the traditional way of having someone push on the pedal while you open the and close the bleeder the person on the pedal needs to know when the pedal travel gets hard. If the brakes are not adjusted up the pedal will not be hard until the shoes make contact. That's the only reason I can think of to adjust the brakes first. My last two years at work I was by myself at night with no one to push on the pedal and no brake bleeder, the phone company wouldn't pay for them. I gravity bled every brake job and that worked just fine. If you step on the pedal and it goes down mor than normal and then immediately step on it again and you get hard pedal they need adjustment, If it still feels spongy, they probably have air in them.

If you are doing disc brakes always open the bleeder first before puching the piston back in, that way you're not forcing that old fluid back up into the system. Then when you are bleeding tap on the caliper. This releases air bubbles clinging to the cylinder walls and it will speed up the process. That was from a factory Ford Brake class I took.

The Teflon tape on the bleeder would only be required if you were using a vacuum bleeder The hose is hooked on the bleeder and it will pull air in through the threads of the open bleeder. It still works it's just slower without the tape.

[Woodie1]

Thanks Flathead Fever.

[Flathead Fever]

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Originally Posted by Woodie1

I worked on our 1939 brakes a little last year. I had to replace 1 front wheel cylinder because of leaking & corrosion. I have since learned I should have replaced both front wheel cylinders. I pulled the rubber boot back on a rear wheel cylinder yesterday & it started to weep brake fluid. The car supposedly had all new wheel & master cylinders replaced in 2014. I believe the car sat a lot though. I have the detailed instructions for doing the brakes.

It's always a good idea to replace or rebuild all the cylinders when you find one leaking. If one is pitted, they possibly all are. For safety reasons I would at least take then apart and insect them on a single system. Plus you don't want them leaking and ruining your lining. The lining absorbs the brake fluid or gear oil. You might clean the brakes and they look good but the heat will pull that fluid back out of the lining. For the price of some rubber cups, it will save you money in the long run. We had an EIS wheel cylinder cup assortment with every size cup and boxes of the most common sizes we used. We usually just lightly honed them and replaced the cups. The phone company was too cheap to buy rebuilt kits.

Master cylinders have a residual brake valve that holds a little amount of pressure in the system. This keeps a constant force against the wheel cylinder cups which keeps them tight against the cylinder. This is to prevent them from leaking when not in use. Over time that pressure can bleed off and the cylinders can seep a little. With collector cars that are not driven very often it' s a good idea to step on the brake pedal every once in a while, to maintain that residual pressure. The fluid is hydroscopic, it attracts moisture. It can absorb as much as 2% water a year even in a sealed system. As the pistons return back they can suck moisture in past the rubber cups. This is what causes the rust pits in the cylinders. They would never rust if that moisture was flushed out. At a Ford training class, they said if people would flush their brake fluid every two years the wheel cylinders would practically last forever. I'm guilty of not doing it. I only do it when I do a brake job on my daily drivers.

[Woodie1]

Makes good sense.