Brake bleeding

[blab]

Still working on this, lol.

Turned out that some connections were too lose. I could stop the bubbles during bench bleed. But still had brake fluid leaking from the master during brake bleed. I finally made a little tool



and tightened the connector block to specs. Required more force than expected. So it should be sealed now.

However, now the angle is not good for the rear line:



Hard to see here but the brake line almost goes as high as the lower edge of the lid.

Is it OK like this? I would have to buy more connectors, with no guarantee that I will not end up at the same angle or worse.

[sseebart]

That's a clever tool. I always worry about stripping out that junction block. Do you know how much torque you put on it?

Based on your photo, it's not pretty, but as long as it's not leaking and there's no interference/rubbing on the line, I think it would be fine to run this way.

~Steve

[64ZCODE]

Yes. I suppose you could use teflon tape on the threads and that might give you more ability to adjust the position of the block and not have any leaks.

[blab]

@sseebart, I torqued to 12 ft lbs which is the max amount according to manual. I'll proceed then, have to redo the rear brake line because it's too short for the different angle. The brake line junction behind the inner front fender will be really useful here.

@64ZCODE, when I couldn't get rid of the bubbles I did a test with teflon tape and it sealed immediately. In the end I didn't use it because 'the internet' said don't. Using it would have required extensive research.

[sseebart]

@64ZCODE, when I couldn't get rid of the bubbles I did a test with teflon tape and it sealed immediately. In the end I didn't use it because 'the internet' said don't. Using it would have required extensive research.

A mechanic advised me once to use PTFE paste instead of tape. Since then, I've used it on all threaded connections that require some extra sealing. Easier than tape with fewer risks.

~Steve

[paulr]

@64ZCODE, when I couldn't get rid of the bubbles I did a test with teflon tape and it sealed immediately. In the end I didn't use it because 'the internet' said don't. Using it would have required extensive research.

A mechanic advised me once to use PTFE paste instead of tape. Since then, I've used it on all threaded connections that require some extra sealing. Easier than tape with fewer risks.

~Steve

Every mechanic I’ve ever asked has strongly advised no tape; use dope or nothing.

When I had your same issue, Blab, I removed the tape I initially used (prior to being schooled) and it had degraded pretty bad. I did not end up using pipe dope, just tight seats, but that’s not saying I wouldn’t use it next time.

Bottom line, when I taped, I had seals that lasted a week. Not expert advice, Jmho.

[blab]

I made a new break line from the junction behind the inner fender to the master. Much better now, the old one was way too short. Time well spent.

Still leaking at the master / distributor block connection. Even with another quarter turn it wouldn't seal.

Not sure what I can do now beside buying a third master and another distributor block. Right now I'm so annoyed by the whole issue and the inherent problems of the parts or construction that I might just ignore it for now and let it leak and refill. Then convert to a dual master in winter. The more I worked on this, the more I saw where things can go wrong. Should have done the dual conversion from the start. Going to read up on that now.

Thanks for the tips on teflon paste, I hope I can get it here.

[David Langhorne]

FWIW I had this problem many years ago. I tried a couple of replacement taper thread fittings I got from U.S. as never seen them here in UK.
In the end I took the M/C and fitting to a brake specialist (an old guy who makes classic car brake lines etc). He scratched his head and said that'll never work so he took it out back and melted some copper on it and machined it down to make a compression type end. He screwed in to the angle I requested and never had any more leaks - maybe 15 years now.

[jtschug]

Tape and sealer are made for pipe threads, like used on the heater hose neck and the vacuum ports.

Brake lines use an SAE 45° flare fitting. The sealing is between the tube flare and the seat. The threads just push the two metal parts together with a large force which is intended to create a metal to metal seal. Pipe threads are fine when you have less than 20 psi pressures like the heater hose and the manifold vacuum, but the pressures in the brake line are much higher. If the metal to metal seal of the brake fitting leaks, then doping up the threads will do absolutely nothing to stop a leak. Worse, the sealants can get into the brake fluid and cause a clog.

Never Never Never Never use a thread sealant on a flare fitting. Just don't. It is an amateur mistake.

[blab]

@David: Wish I had someone like that!

@jtschug: The flare nuts seal fine. The problem is the tapered thread of the distributor block that goes into the master. Which doesn't seal when torqued to specs. My theory is that these replacement parts are not exactly like they were back in the day. But yes, getting sealant into the system sounds bad.

[jtschug]

Ah. Tapered thread = pipe thread, it does require a sealant. This must be a '64 because I don't think the disc brake system uses any pipe thread in the brake lines.

[blab]

Yes, '64.

[blab]

What about Loctite 542? Looks like this is made for threads on hydraulic tubing.

[RAVEN]

I recommend that everyone go back and reread this post from the start as items are just going around again, and small things are getting missed.
The brass block is pipe thread, and basically is a one time use per rotational location. Every time you tighten it the block needs to turn a little more, do to its taper to get a seal. Brass on steel Master; brass is soft, it deforms, loss of seal.
Sealant is required on the threads, but it will not make up for the deformation of the brass block due to over tightening. This is why I recommended to get several blocks, and mix and match the orientation to get a correct fit.
Good luck, and keep on trying, you will get there. Do not give up.

[rzcrisis]

Totally agree with Raven on the brass block fitting. Goes the same for copper type washers. Both soft metals. Recently helped a fellow tbirder with a fuel leak on a 1957 bird carb and ended up purchasing a new brass banjo fitting to address it. No overtightening and do your best to make sure your connections are square and well fit before tightening down. The 57 is now a happy puppy with no fuel leaks!

Randy