Final Brake Bleeding and adjustments

Personally I've expeienced more controversy with people claiming the brakes are soft/hard, etc.

Street cars in my views should have a softness to them. They are not race brakes.

If you need to go further, research just about any Ford service manual of any car of any year that is using power brakes.

You are going to find a picture of a brake pedal having the effort on the pedal measured with a dial gauge.

That's how that is measured. Not weather you were barefoot, had Nike's on or your bed room slippers.

Production cars are made for average everyday people, not Nicky Lauda's demands.

You are getting nowhere unless you read pressures directly from the master and the calipers. You need hard numbers to compare to.

Fully agree Doug.  

Percy, I can't tell about your hoses from here. Braided-stainless-reinforced plastic lines pretty much all look alike. But inside are the real differences: The original lines had/have translucent whitish poly-tetra-fluoro-ethylene (teflon) hose and use the braid as reinforcement & protectant against weathering and external-object damage. Others use poly-sulfone plastic (not translucent) that are higher temp rated than teflon. The fittings were/are 6061-T-6 aluminum with 410-stainless steel hose attachment parts, as sold under the Aeroquip brand. They are aircraft flight-certified and test loaded to over 3000 psi burst pressure for dash-3 and -4  sizes. They work fine for brakes & clutch hydraulics and are monstrous-overkill for automotive fuel, cooling or vacuum systems. The 37-degree cone fittings do not seal well against AC freons. The slick teflon lines flow 4- 5% more fluids at any given pressure than other plastics.

There are visually identical hoses available in which NONE of the listed plastics or metals are used. On our Sept '72 car, there was a stock braided-metal hose used as part of the fuel or smog system. It was visible from the engine compartment and ran across the rear firewall above the engine screen to- I think- the charcoal canister. Since our canister and the hose have been gone for decades, I can't really remember. Inside the braid was a cheap rubber hose crimp-fastened to fittings and the braid was dull tin-plated mild steel. It leaked. I've found others that use brass inner hose fitting parts. They seem OK but cannot mix-&-match.with stainless Aeroquip stuff. I stay away from those. YMMV-

Bleeder valves seal by the tappered seat, not by the threads. You can use some anti-seeze on the threads but keep extras and expect that if they have been locked up and unbled for years that you may strip them out.

For some still unexplicable reason, often the hex is not a full 3/8" and more like 11/32".

I just replace the valves when I do a major bleeding which is a good thing since you should flush out the old fluids periodically anyway.

Watch the color of it. It changes color as it absorbs moisture which is natural just from the atmospheric humidity.

Caution is advisable on ANY pure stainless steel threaded parts. "Stainless" has a nasty habit of stripping the threads for no reason at all. You need to use anti-seeze on them but that doesn't always eliminate the issue.

Neither can they take the torque load often required in the original engineering specs. I've had them pop out of the casting. Stainless to an aluminum casting in particular is just not a good idea at all.

I've had aluminum -3 ends SPLIT from just the normal brake pressure generated by the master.

There are SOME ordinary AN fittings not made in -3 sizes. Take a different route.

You are better off using the cad plated steel hose ends and fittings and never use aluminum fittings on brake lines. They just don't have the tensile strength of steel.

You can create reliability issues by trying to be too fancy because you want to add bling.

In panic stops master cylinders can produce instant pressures of 900 to 1000 psi loads in the lines. With the wrong materials you can absolutely strip the threads and pull the fittings out. That probably isn't a good thing.

Remember that "braided metallic" lines and fittings were initially adapted by racers from aircraft applications but aircraft has regular document service intervals that will often require complete replacement of hoses and fittings periodically.

AC lines generally use SAE 45° fittings but good luck on getting even those to completely seal in your refrigerant. That's why you need to recharge your system  periodically and often annually.

All materials have a porosity to them. In the case of A/C lines, some materials are better then others.

It's like raw magnesium castings that leak air when they are cold because the porosity at a molecular level when cold becomes larger then the "air" molecules and escapes through them. You have to coat magnesium wheels to prevent that.

A/C lines are that way but have less porosity so they leak right through the material but at a much slower rate. If you get two years without having to recharge your Pantera's system, you did good.

Those are long hoses and give more surface are for microscopic leaks.

Goodridge was the first company to produce braided stainless steel brake lines for automotive use and established them as the standard in motorsport around the world. Each line they sell is tested to 3000 psi.  Their brake line kits are the best money can buy.  I promise you these are not your problem.  The Pantera line kit is an identical fitted set to to stock in terms of fittings, down the the washers and banjos. They will outlast most other components of the car once installed properly.

FWIW, I use several turns of teflon tape around bleeder screw threads- not as a sealant exactly but to keep air from being sucked back in during bleeding when you release the brake pedal after each stroke. Might not happen with pressure or vac bleeders but it does when you're doing it by yourself. As several have said, the actual fluid sealing is on the tip of the bleeder needle, not on the threads. Take the tape off after you're done bleeding if it bothers you.

Thanks so much for all of the detailed information and advice. This is the first time I have used gastight teflon around the bleeders and I think it did improve the prevention of air being sucked back into the bleeder. I would do it again like this. I would also go the extra yard to manipulate the front calipers to extract the last of the air.

I have re-inspected the Goodrich braided lines and steel fittings and they are very very solid. No issue there  re metallic differences.

Dougs comments on gas porosity in metals and hoses are very interesting . At the risk of going off topic I offer a  personal observation on this.

A good example of gas porosity is in  heavy wall high pressure pressure vessels working in  hydrogen rich environments. These in operation can develop blisters on the inside surface where hydrogen seeps through the steel ( one molecule at a time ) and binds up at a point of laminar inclusion in the plate. This results in a high pressure  hydrogen bubble inside the steel that, if untreated, will split the pressure wall. Treatment was simple and nerve wracking   - use a mag drill to puncture the blister.

Unfortunately the high pressure hydrogen would come out the hole when it reached the blister and spontaneously ignite - very tough on the front of the mag drill and on the operators nerves !! ( .....you always seemed to be holding your breath  ....!!)

This was the most graphic example of osmosis of gas through metal that I have seen. A little off topic for this post but interesting none the less.

It is surprising to most until they get into the engineering.

Another example that comes to mind and not to be off color. That is not my intent.

Standard latex condoms are only 32% effective against the HIV virus. What exactly is only 32%? Beats me. I need explanation of that term.

What I read was that the HIV virus is small enough to pass through the porosity of the latex. How small is that? I don't know. Ask the engineer but still very concerning scientific fact.

The first I came into contact with this subject was with magnesium wheels. American was making them in the '60s uncoated. Just as cast and machined.

Racers were having issues with the tires the next day as they were going flat. No leaks could be found.

At some point it was found that it was the porosity of the magnesium itself would vary according to temperature.

Maybe some of you Aerospace engineers are aware of this from the beginning but I have to learn by the empirical method. So far it hasn't been fatal and I suppose as long as you hear the bullet go past, you live...for now?