The Stovebolt Site Forums The Shop Area Driveline 1957 GMC stock brakes

I'm looking to replace my master cylinder, and I would like to know if the current brake line configuration leaving the master cylinder is stock or not.
Can someone share a pic of their stock master where lines connect and then split to front driver side and the rest?

Thank you

I don't have any pictures (and my '57 is long gone), but the Master Parts Book calls out different part numbers for depending year and model. But the interesting thing is they have the lengths of the fitting listed. Might help??

jmoore - If you could post pictures of your current setup, it would help identify if it's stock or something else. I have a 1955 GMC Model 100-500 Shop Manual, but it doesn't provide a diagram of the lines. The only hard copy GMC Master Parts Book I have for 1957 is a 1955-57 Chevrolet/GMC of Canada Book given to me a by a generous fellow Bolter. It does have a drawing, but it's lacking in clear details, just a general this line goes here/there/etc. I think it's actually the same drawing as in the US 1957 Chevy Master Parts Book. Gotta go look at that one.

frame or firewall mount

Stock frame mount. I'll try to snap a picture.

I can describe as best I can.... short line from the MC to a "T" fitting.
Lines going back and forward to "T" fittings. Lines going to each wheel, left to right.

Is the first fitting leaving the master stock? The short line from there to the first tee seems amateurish.
From tee is one line forward to driver front, the rest fed from line going toward the rear then splitting off farther back to feed the other three.
Thanks for the input.

I believe that the plug marked by the arrow in the attached pic could be removed and a brake line connected there. That would do away with the funky short line and tee hanging out in space.

IIRC '54 and '55 trucks used that spot for a line to the left front wheel with the other line going straight out of the MC over to the right side frame rail and a tee to the right front wheel and to the rear axle (both wheels). The earlier trucks (my '51 included) used a single line from the MC to a tee on the right frame rail and another tee at the RF wheel branching over to the LF wheel across the front crossmember.

[on edit]It looks like the '57s would have the same configuration. The second picture is a composite from the 1929-1957 Chevrolet Parts and Accessories Manual. It show the brake diagram and the 1957 brake line lengths. I believe the GMCs would be the same.

JMoore: I'm pretty sure my '57 GMC had a brass fitting on the back of the master cylinder that screwed into the master cylinder and had two female connections for brake lines. One went to the left front brake. The other followed a crossmember behind the engine to a T on the right side frame. From there one line went forward to the right front brake hose and the other went rearward to a hose that joined another T on the rear axle.

But I'm 78 years old and I swapped that master cylinder out for a 2 pot disk/drum model in the early/mid 1990s, so I could be wrong. Some days I can't even remember what I had for breakfast by noon.

Bill, based on my research, you're likely spot on. I don't think you're wrong.

But I know about being old. What day is it, anyway.

Thanks everybody.

And for some reason, no one makes a set of pre-made lines for a 57 longbed for comparison that I can find.
Everything else but that.

BD - jmoore's "long bed" is a GMC 150, 3/4 ton so the 1/2 ton long bed lines above aren't going to be the same. Classic does offer a 1955-56 Chevy/GMC 3/4 ton long bed line set but that doesn't say it covers 1957 3/4 ton long beds and the 1958-59 3/4 ton line sets don't indicate long bed either.

what would be the difference? 3/4 -1/2 ton. add a line from the parts store. They have different lengths.
Id run lines like a 58/59. Simple. Like I described. MC drivers side frame mount

Can't you just duplicate what's there in new line? Brake line isn't that difficult to work, and the flaring tool is cheap and easy to use. If you're not building a show truck you can just make it work. If you are, then buy the Blue Point (Snap-On brand) bender and carefully duplicate the original lines.

If you have the originals and don't want to make your own, InlineTube will make a new set for you using your old ones as templates.