Technical Why does almost every fitting on my brake system leak?!

So anyway, I annealed my copper washers, plus my unions. Also quenched them...I think that really helped since I got the front to seal up.

One union sealed up right away, the other gave me shit until I realized it was one that I did not anneal.
Swapped it out for one that I did and it sealed up first try.

I recently found that my parts store has 72" lengths which would be perfect to get rid of these things. If they give me shit one more time they will be out, but as of now they are fine.

The tip regarding loosening and retightening worked for a couple of them. Pretty stoked!

Right now I have one new leak that popped up. It's a tiny piece that goes from my MC to the residual valve. Plans are to just get it out of there later this week.

Thank you all for the awesome help! The combine of all the input has put me in a much better spot with this thing.

By the way, here's my little masterpiece, last piece had a union in the middle.

 

Glad to hear you are making progress.

 

You can get 25' of cunifer brake line on Amazon for $26. That eliminates needs for unions, removing potential leak points from the system.


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Had the same issue with some new so-called " early Ford banjo bolts". Bullshit! They're late model disc brake hose to caliper attaching bolts; not long enough and no inverted taper on the end!

 

As the OP has stated his unions worked better when they were soft (annealed). The reason for brass unions and washers in the system is so they conform to the steel flare's peculiarities (minute flaws). So, I would think a steel union would work even worse than a brass one. Also, I don't re-use unions and other brass fittings if at all possible.

I make sure to use brake line wrenches, and tighten/loosen/retighten each nut a few times before I ever put fluid in that line. I get real nervous giving that nut a big crank, but it's better than having it leak after ten minutes of fluid in the system.

 

While we are on the topic of unions...one of mine was leaking this morning. So out they go

 

37º is AN (Army/Navy) or JIC (Joint Industry Council, less precise than AN, same theoretical specs) flare. It is not specific to stainless steel lines. It can be used with steel, stainless steel, aluminum, etc.

I double-flare all 45º lines, including stainless steel, but those are rare, as customers have almost never requested it.

I have not seem a OEM or OEM-style master cylinder, combo valve, block, tee, caliper, wheel cylinder, power steering component, or transmission fitting with a 37º cone in it, ever. If you wanted to get a 37º line attached, you'd have to use an adapter, which is yet another avenue for leaks, and clunky aesthetics (and expense).

 

I have one union in my Ford that went with the disc swap, no leak. They're okay here and there but the best way to go is in a single run. I did my brake conversion with the green NAPA lines, not the soft coffer stuff. I almost got it but don't like the look of it un-rolled. I have never seen it in straight lengths. Another plus of the NAPA pre-made lines, it can cut your flaring down by 1/2.

 

gimpy, I used the word "usually" for that reason............................

 

AutoZone carries straight sticks of NiCop in useful lengths.

Unrolling and straightening NiCop isn’t hard to do.

 

I have since found it in straight sticks. I still don't like the look of straightened out lines on my cars.

 

There are all manner of tools for sale that will take a coiled line and render it dead-straight.

 

I know this is an older thread but I eliminated ALL leaking flare fittings when I purchased a lever action flare tool from Eastwood. It’s available from others but every flare is perfect and it leave almost no marks on the tubing. They are very quick to use. I clamp it in my bench vice and lightly lube the tubing. They also sell a tighter hand bender.

 

Consistently leaking flares had to be a tool issue.

I ran for years with a manual KD Tools flaring tool. As it wore out it rendered a lot of leaking flares.

I have a hydraulic one now and the only problematic flares I do now are the ones that I do before I put the nut on!

 

I've replaced , installed , fabricated , in general worked with many hydraulic assemblies for at least 60 years , other than my making a couple bad flares early on & a bad (whoopty doo) SS brake hose from speedway , I really don't recall having problems/ leaks . I just don't understand all the troubles ?

 

operater issues maybe

 

Problems I've had was trying to use a smaller flare tool, such as KD 2199, on the pre-sized thick wall pre fabbed tubing that NAPA sells. Two inches too long, lop off the end slide on the ferrule, try to re-flare, never worked out as well as it should have.
Roll of normal brake line or Ni-copp stuff was never a problem.
Trying to modify the prefabricated stuff was where I had a problem with flaring.
As for leakage, I'd have the occasional weeper, would end up just loosening the fitting and then tightening the begeses out of it. I use the largest(stiffest) adjustable wrench that can fit in the area on fittings.

Better than any of those fancy flared wrench sets I've bought over the years, they flare out when you put some torque on em, must be why they call em 'flare wrenches'

 

buying the correct good quality spanner is allways good advice

 

Affirmative.

You can get used Snap On ones on eBay.

 

Also said already but there’s a lot of junk fittings around today. I had a leaker messed with it a while then pulled the fitting. The threads stopped short of letting the flare seat tight. The nut was tight but lightly touching the seat. Also messed up the threads on the end of the nut.
I’ve been turning wrenches for more than 50 years and crazy stuff like this is becoming way to frequent with this global economy