Spongy Brake Pedel Help

Discussion in 'Fox 5.0 Mustang Tech' started by Slo5Oh89, Jun 17, 2013.

  1. Guys I need advice.

    I upgraded to mm brake hoses I bled the brakes had a shop bleed the brakes. Was bit better but pedal was soft. They said no air in it. If u get 3-4 pumps in when slowing the pedel firmed up.

    I have had zero issue before I need ideas other than the master cylinder failing with less than 80k miles on a 89. I mean im pretty sure I did not put calibers on upside down. iv heard u cant get all the air out if they are on wrong side

    Help please!
  2. Sounds like you should double check that you didn't do what you just mentioned. Bleeder valves should be on the top of the caliper so all the air can escape. If you MC was good before the upgrade then there's a fat chance that suddenly it's failing.

    Another thing to remember (and yes shops can mess things up too) when bleeding brakes you start with the RR brake, RL brake, FR brake and then do the driver side. Use a DIY bleeder kit. Don't let the MC get to low and suck air.
  3. Here is a picture u can see the bleeder in the pic. I need help guys I am so frustrated with this car right now. Did all these suspension upgrades for 3 months get it all done now this brake issue.

    Can anyone tell if the calipers are om right from pic?

    Attached Files:

  4. Take a look at this picture. See the red circle where the bleeder screw is? It should be at the top of the caliper.

  5. Yes I see the picture and mine appear to be pointed to the top when I look.. can anyone see from my picture?
  6. Garden Sprayer Pressure Bake Bleeder

    1 each pump type garden sprayer, 1 - 1 ½ gallon capacity (size doesn’t matter much, it just has to be cheap and small enough to be easy to work with)
    6-10 feet 3/8” clear plastic tubing
    1 each ¼” brass pipe tee
    1 each ¼” pipe to 3/8: hose adapter
    1 each pressure gauge 0-60 PSI or so – all you’ll ever need is 5- 10 PSI, so the gauge range doesn’t have to be high.
    1 each large rubber stopper – this is the hard part to find. It may take some searching to find one that is a snug push fit to the inside of the filler port on the master cylinder. You can use silicone rubber to seal a brass fitting to an old master cylinder cap, but they tend to leak too much.
    Home Depot or Lowes has some ¼” brass pipe stock that is continuously threaded in the electric lamp repair department, along with the brass nuts that go with it. This is better than a pipe nipple, since the nuts can be used to secure the pipe in the cap or stopper.
    OR if you can’t find the threaded pipe stock,
    1 each ¼” nipple, 1 ½”- 2” long

    The rubber stopper needs a hole drilled in it for the ¼” pipe nipple or threaded pipe stock. After you drill the hole, use some silicone gasket sealer to seal the pipe nipple as you push it into the rubber stopper. If you used the threaded pipe stock, use the nuts to secure the stock into the stopper.

    If you can’t find a suitable rubber stopper, an old master cylinder cap can be used. Drill a ½” hole in the center for the pipe fitting. Cut the brass pipe stock to about 1”- 1 ½” long, the exact length isn’t too important. Push it through the hole in the master cylinder cap and thread one nut on top of the pipe stock where it sticks though the cap. Put another nut on the other side of the cap to lock the pipe stock in place. Apply some silicone rubber gasket sealer to both sides and when it is dry, screw the ¼” pipe that sticks out of the top of the cap into the tee.

    Remove the sprayer hose and wand from the garden sprayer. You may find it easier just to cut the sprayer hose off short and connect it to the 3/8” plastic tubing. The idea is that the 3/8” tubing connects to the pickup tube inside the sprayer in a reliable, leak proof fashion. Another alternative is to remove the spray nozzle from the end of the spray wand and connect the 3/8” tubing to the wand. This leaves the hand valve in place and may be useful to start/stop the flow of brake fluid.

    The 3/8” plastic tubing connects to the pipe tee using a push on hose barb type adapter. The pipe tee has one port for the gauge, one for the 3/8” hose and the other to connect to the rubber stopper or master cylinder cap that you modified.

    Fill the pump sprayer with a quart of brake fluid. Set the garden sprayer on the ground and screw the pump handle down tight, and pump until brake fluid fills the plastic tubing. Then put the modified stopper or master cylinder cap on the master cylinder and pump slowly to make sure that nothing leaks or pops loose. No leaks, continue pumping until you get 5-10 PSI.

    Start with the brake assembly furthest away from the master cylinder. On 5.0 Mustangs, it's the passenger side rear brake. Follow up with the driver side rear brake, passenger side front brake and the driver side front brake. Put a 6”-12” length of clear plastic tubing on the bleeder ports. Then open the bleeder ports on the wheel cylinders one at a time and bleed until the bubbles are gone. I use a 2 liter soda bottle with a coat hanger to catch the fluid . DO NOT REUSE THE OLD BRAKE FLUID. Repeat the process until you have finished all 4 wheels. You will have to pump the sprayer several times to maintain the 5-10 PSI needed to do the job. When finished bleeding, loosen the pump handle to relieve the pressure, remove the stopper/modified master cylinder cap and test the pedal.



  7. So can anyone see from the picture I posted if the caliper is on right?
  8. Nobody can SEE your picture but I can virtually guarantee that if all you did was lines, didn't install a proportioning valve or mess with the rear brakes or stock master cylinder, and the brake pedal will hold pressure once it's pumped and held, then you have the calipers on upside down.
  9. Nice little setup J! I've used a 1 man bleeder from Matco for years but this is pretty cool. Wonder if you drilled a stock master cylinder cap and screwed in a pipe fitting with the hose attached to it then to the pressure gauge if that would work?
  10. I can see your picture but it doesn't show the bleeder valve. All I see is the brake line disappearing behind the caliper and can't tell if it's connected at the top or bottom of the caliper. Get off the computer and go look for yourself bro!

    Awesome MacGyver brake bleeder Jrich!
  11. After you have bled it to death,
    if this part of the project took a while, the MC could have chosen then to die. Any time is a bad time as any other for the MC to go.

    The other thought is if the vac. hose is hooked up right to the M Cyl. It would be very easy to bump it part way out while working in the area and you would have to pump the pedal.
  12. I will post a better picture of the brake bleeder orientation. FoxMustangLvr iv spent hours messing with it so I have seen it. I pretty much am at a loss other than the MC. And im pretty sure the calipers are on the correct side. Thats why i was asking to double check I will post better pic.

    Thanks for the help as always guys.

  13. When you say things like "i'm pretty sure" instead of "i'm positive" it leaves room for doubt and keeps the conversation open about it possibly being a problem with your spongy pedal. If you are POSITIVE that the bleeder valve is on top then that rules out your calipers being on the wrong side.

    Now that we have ruled that out I would have to ask, How was the brake bleeding was performed?
    Did you completely flush all the old fluid out with new fluid?
    Did you simply "bleed" the brake lines?
    Do you still have drums on the rear brakes? Have you checked you MC's on your drums for leaking?
    You said you also went to a shop to have the brakes bled, shops mess up too. Heck, I wouldn't trust them to air up my tires.

    If it were me, i'd check my rear drums for bad MC's, if those are OK then i'd FLUSH those brake lines with brand new fluid. Cheaper and easier than anything else. Besides, if you haven't flushed out your brake lines, how old do you think all that fluid is? 10 years? 15 years?

    Good luck!
  14. The truth is, it could be a number of things can be causing this

    1. bad MC/seals on piston
    2. hoses
    3. wheel cylinders
    4. caliper piston seals
    5. bleeder screw valves not closing all the way
    6. calipers installed upside down
    7. leaks at stock prop valve or hard lines/fittings The lines are 20 years old and can break, rust

    spongy feel can also be from
    1 Old rubber brake lines stretch
    2 Improperly bled brakes
    3 air in system
    4 improperly adjusted drums or e brake
    5 old fluid that has moisture in it
    6 crap brake pads
    7. bad vacuum booster or vacuum leak
  15. And if it was bled by stroking the pedal, you could have hosed the MC. Which is why I mentioned, if it'll hold pressre on the pedal once it's pumped up. But I think the board is tired of speculating without more facts.
  16. Ok guys I took it to a shop I trust they did find some more air but still a little spongy. And the determination was after that the MC is failing but the power booster is working fine.

    Could you guys give me an overview of what that takes to replace the MC? I have not replaced one in the past.

    Again thanks for the help!
  17. Not to come across like an ass, but if you had issues with bleeding the brakes after simply swapping hoses, I wouldnt suggest you tackle replacing the MC. In addition to bench bleeding the MC, you will need to make sure the MC piston length is properly adjusted, and then bleed all 4 lines again. You'll run into the same problems.

    I would not get a reman MC as I have found the tolerances in the bores suspect and often lead to premature failure.
  18. No mikestang63 your not coming across as an ass! I was asking to see if its something I wanted to just let the garage do! So all good man! I do think I will just have them do it was just seeing if it was a easy thing to do with brake inexperience.
  19. Are these stock brakes??

    And the only change was to add MM SS hoses?

    How were the brakes before the change? Were they good?

    What banjo bolts did you use? The ones supplied in the kit? Any leaks?

    If you double pump the brakes, does the pedal feel improve? In other words, find a good long straight road and get up to speed and then get on the brakes. After a few seconds, do a quick release and reapply of the brakes....basically a double pump. Does the pedal feel firmer?
  20. I tried drilling the stock cap and it leaked badly. The rubber stopper makes a better seal.