who has done a front disc brake conversion, help

Discussion in 'The whoa and the sway.' started by jaye, Aug 7, 2018.

  1. knucklebusted

    knucklebusted Well-Known Member

    I think you can modify the old drum hose brackets to work as they have too much metal and you can file/grind them out a bit. I got the ones off the car I got the rest of it from but it didn't have the right prop valve nor the hold off on the master.
     
  2. BrianTrick

    BrianTrick Brian Trick

    Yes,correct. The small hose brackets that bolt to the frame have a different-shaped opening for a drum hose versus a disc hose. I have some disc brackets,if needed,but most people just modify the opening with a file. There are also different thicknesses forbthe brackets. Some are a single thickness of steel,and some have two layers of steel. I have seen them both ways for drum & disc. I think it was a plant/supplier thing.
     
  3. BrianTrick

    BrianTrick Brian Trick

    That style sensor plug was used in the later 70’s. You can get it to work like that,with a little creativity. Trimming some of that sleeve down,so you factory plug/boot will fit snug.
    Your first idea might be to switch that sensor with the original in your old block,but I have found some of these to be different sized tapped holes. Again,depending on the manufacturer of the aftermarket valve. I know Inline Tube offered the correct style sensor,as I have bought a few.
    The first thing I would do is check to make sure all of your brakes lines thread into their respective holes. Some of these parts vendors are trying to sell a universal valve,for GM Ford,etc.,and that is where you could run into the chance of having different port/thread sizes.
     
  4. jaye

    jaye Well-Known Member

    I’m having some issues with the m/c leaking where it bolts to booster. Is the booster and pushrod the same for drum & disc ? Do I need to change the booster rod location where it bolts to the brake pedal. Pedal feels ok and stops when initially stops, try pushing to the floor and it will eventually not but not right away, like when floored it’s losing pressure which is probably due to the leak .
     
  5. BrianTrick

    BrianTrick Brian Trick

    The booster itself is the same for drum or disc. Anything with a booster uses the lower hole on the brake pedal. The manual brakes use the upper hole.
     
  6. jaye

    jaye Well-Known Member

    I changed the master cylinder last weekend and
    finally got a chance to test drive this morning and so far its good. After a few miles I'll get it up on a lift and check again for any leaks.
    Brian thanks for all the information you provided
     
  7. BrianTrick

    BrianTrick Brian Trick

    I hope it helped. Keep us posted.
     
  8. knucklebusted

    knucklebusted Well-Known Member

    Well, my combination valve didn't work. The lines are a different size. I've sent it back to Amazon.

    Brian, do you have a part number/supplier for the ones you've used that are drop in replacements on a drum/drum to disc/drum car?
     
  9. BrianTrick

    BrianTrick Brian Trick

    I will see if I can find it.
     
  10. jaye

    jaye Well-Known Member

    All is still brakes working great
    thanks everyone
     
  11. Schurkey

    Schurkey Silver Level contributor

    The NUT on a given section of brake tubing can have one of several thread sizes. The OEMs do this to positively prevent some idiot from screwing the tubing into the wrong port of a master cylinder or control valve.

    Easy enough to buy an assortment of tube nuts (flare nuts) from Summit or some other supplier, and just slide the proper-sized nut on, before flaring the tubing.

    Rule-of-thumb for brake plumbing is that if a tube is supplying ONE wheel cylinder (including calipers), the OEM will probably use 3/16 tube. If a tube is supplying fluid to TWO wheel cylinders, the OEM will probably use 1/4 tubing. So on a combination valve, there's two 3/16 tube outlet ports for the front brakes, each front brake has a separate tube supplying fluid. There'll be a SINGLE, 1/4" tube outlet for BOTH rear brakes, the 1/4 tube runs the length of the chassis ending at the rear brake hose, which then "Y" into left rear and right rear 3/16 tubes at the rear axle.

    Examples of flare nuts for 3/16 tubing
    Regular
    https://www.summitracing.com/parts/sum-220137
    Stainless steel
    https://www.summitracing.com/parts/sum-220237

    Other sizes are similar.
     
    Last edited: May 3, 2019

Share This Page