Brake line unions

Discussion in 'The whoa and the sway.' started by rh455, May 20, 2005.

  1. rh455

    rh455 Well-Known Member

    Do you think it's safe or okay to use a union in the 1/4" brake line that runs to the back of the car in the frame rail? I'm using a Wilwood proportioning valve and I'm installing it next to the master cyl. Is it too risky or should I just order a roll of tubing and bend up a new line?
     
  2. BillMah52

    BillMah52 Well-Known Member

    Reynold,
    Mild steel or stainless? You can use the unions if you like but make sure you have the correct double flare on the ends of the tubing and have the right unions. Better safe than sorry.
     
  3. 12lives

    12lives Control the controllable, let the rest go

    Some stock GM cars and trucks used unions, like Bill said, use the double flare (OEM if you can) and you should be fine. I don't know the rules for racing, so if you are going that route check the tech inspection rules.

    - Bill
     
    Last edited: May 21, 2005
  4. rh455

    rh455 Well-Known Member

    Bill
    It will be mild steel lines. Do you mean inverted flare or double flare?
     
  5. GStage1

    GStage1 Always looking for parts!

    If your lines are questionable, contact www.inlinetube.com
    They carry a kit to relocate the prop valve to the master cylinder (70-81 F-body style) for our 68-72 A-body cars.
     
  6. bignastyGS

    bignastyGS Maggot pilot

    Reynold,
    Do yourself a favor and buy quality fittings too.I needed to make a union in my lines and spent 3 bucks on one union that will accept the std ends on brake lines.Use a double flare kit and keep it safe.It takes a little more time to double flare it but much safer in the end,and by all means DO NOT use a compression fitting!!!
    Pat
     
  7. rh455

    rh455 Well-Known Member

    George
    I'm using Gary Kubisch's idea on a proportioning valve. I also went with a manual m/c from a '73 Chev truck. The only difference is the large reservior is in the back vs in the front like GS power brakes so I'll swap the lines front/rear at the m/c and use 1/4" line to and from the Wilwood prop valve. The other side of the prop valve bracket is the Hurst line loc. I'll run 1/4" from the m/c to the line loc then 1/4" from the line loc to a tee where I'll split into 3/16" to each front caliper.

    Pat
    To clear up my confusion, inverted flare is when it flares twice outward like a bell. Double flare is where it flares out, then back inward? Want to make sure I get it right because some of the brass fittings I have are inverted meaning that looking into the fitting, you'll see a flat area on the outer edge then it comes up to the flare to an orifice.
     

    Attached Files:

    • mc3.jpg
      mc3.jpg
      File size:
      56.5 KB
      Views:
      93
    Last edited: May 20, 2005
  8. BillMah52

    BillMah52 Well-Known Member

  9. rh455

    rh455 Well-Known Member

    Guess I'd better go buy one of those.
     
  10. Truzi

    Truzi Perpetual Student

    By a union I hope you don't mean compression fitting.

    Even if you don't, why not just run some new line? After all, you're adding an after-market proportioning valve, not fixing a broken line.
     
  11. rh455

    rh455 Well-Known Member

    No, not a compression, a union just like AN line unions. I would run a new line but I'd have to order a roll of 1/4" line and pull the rear suspension and the trans x-member. The line is about 12' and the longest sticks you can get are 5' or 6'. I planned on keeping all the original style parts that I have (new master/booster, original prop. valve, and hardlines) in a box in case I decide to go back power. If I use a union, I can use the existing rear hardline and make a new line to the new prop. valve(like an extension). If I decide to go back power, or original, I can put the original valve back where it was with the original hardline.
     
  12. Truzi

    Truzi Perpetual Student

    Oh. That does make a lot of sense. I've used unions when patching together daily drivers, and have never had a problem with them. (Even used a compression fitting once with no ill effects... but I'm much better now).
     
  13. 12lives

    12lives Control the controllable, let the rest go

    Reynold - when you buy the lines from a shop they come with "OEM" flares on the ends. That's what I meant - I don't know the technical term for them (double or inverted). The advice I got on this board was that it is difficult to make the "OEM" flare without cracking the flare or otherwise messing it up. I used the "over the counter" lines with pre-formed flares and used the union made for those lines. This was not an A body, but similar requirement.

    - Bill
     
  14. rh455

    rh455 Well-Known Member

    Thanks Bill. I don't know what I was thinking. Double flare is similar to standard flare, but I guess the technical name is inverted. The "other" flare that I was thinking of is ISO which is a bubble flare. :Dou:
     
  15. DaWildcat

    DaWildcat Platinum Level Contributor

    Reynold, below is an illustration for an inverted double flare. Common tube-to-tube unions use this design out of the SAE J512 & J533 specifications; the 90 (45) version is the most common. The 2x wall thickness at the sealing surface is there to resist splitting and is what's needed for high pressures as seen in brake systems.

    [​IMG]

    Devon
    (fuel & brake engineer)
    :Brow:
     
  16. rh455

    rh455 Well-Known Member

    Thanks for the info Devon. I bought a double flare tool this past weekend and worked ALL day Sunday on the lines. Double flaring is a bee, eye, tee, sea, eight-ch! My hands are killing me. All done now with the front and the union seems to be fine. The brake hose at the caliper keeps leaking on the left side. I've put three sets of copper gaskets on it and it STILL leaks. Tomorrow I'm going to Advance Auto to get a few more pairs of 'em and I'm going to clean the hose surface and the caliper surface with lacquer thinner and scotchbrite. THAT oughta do it. If not, I might weld the darn thing on there. That'll fix 'er! :laugh:
     
  17. 1979SHX

    1979SHX derevaun seraun

    From your pictures, it looks like you are using at least some AeroQuip-style fiittings. Be aware that brake lines and AN fittings are different angles....45* (brake line) vs 37* (AN).
     
  18. rh455

    rh455 Well-Known Member

    Reid
    The photo is of Gary Kubisch's car. Mine is similar but used standard brake line fittings. The Wilwood porportioning valve and Hurst line loc don't have brake line flares in them. They're square (open ended). On the m/c he has standard inverted flare fittings.
     

Share This Page