Master cylinder brake lines

derjackistweg · Mar 17, 2018

I got the issue that my brake line @ Master cylinder is not tight. It Leaks.

My mechanic said he was not able to fix it, or he thought he did - who knows.
He said it's unusual stuff.

I noticed recently that one line, the leading one, has no nut between the brake line and the cylinder. The other one does.
This doesn't look stock/OEM to me. Can anyone underline that?

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DrCharles · Mar 17, 2018

That looks exactly like the master cylinder on my '93 F250. MC says "Ford" right on it.

I believe the front disc brakes have a residual pressure valve (which is what the "nut" is) but both should have the standard inverted-flare connection to the steel lines.

79jasper · Mar 17, 2018

Pretty sure you are bassackwards. Residual valve is for the rears.

I would replace the line, or at least a new fitting and reflare. Remember, it HAS to be a double flare.

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DrCharles · Mar 17, 2018

I think you're right, 10 psi residual for drum rears but I remember reading something about 2 psi residual valves for disc brakes too.

Which brings up an interesting question, which port on our master is for front brakes and which is rear brakes? I haven't traced the hard lines.

Is it different for Fords... on my Mopars the rear port (closest to the firewall) is always for the front brakes.

Thewespaul · Mar 17, 2018

Rear port is rear brakes iirc. Only residual on the front brakes would be from gravity

derjackistweg · Mar 19, 2018

thanks guys :Thumbs Up

I actually my 1993 E350 Quigley does have drum brakes in the rear. And it has a rear ABS.

- What does "Residual valve" mean? Does it reduce the brake pressure to not lock the rear? Which it does quite nor really.
- What does "double flare" mean?

Actually my rear ABS light came on in the dash, after it fitted 315/75 on one side and then turned the truck. Turning shouldn't be an issue though.

79jasper · Mar 19, 2018

It just keeps a slight pressure to the rear drums.
Double flare is the flare of the fitting. It's stronger than a single flare.

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Master cylinder brake lines

derjackistweg

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DrCharles

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79jasper

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DrCharles

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Thewespaul

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derjackistweg

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79jasper

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