Car doesn't stop?

Discussion in '2007+ Mustang GT500 Tech' started by Speedboosted, Aug 28, 2016.

  1. Speedboosted

    Speedboosted Found missing cylinders

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    Been fighting an issue on my dads car for a few months now and I am just lost. Car is a 2011 GT500, lots of drivetrain and suspension mods and.

    The initial few mm of brake pedal travel yields reasonable braking performance, but anything past that and it just seem like there is no more force, like at all. It stops the same by just barely pressing on the pedal as it does slamming it down all the way.

    When I first started noticing it, I thought it was just glazed over pads and rotors so I took a scotch brite wheel to them and cleaned it off, nothing changed. Then decided to flush the factory brake fluid out and put in some generic DOT4 and of course bleed them. The initial little bite was better after bleeding, but still the same dead pedal after it.

    Fast forward to yesterday when the fresh Stoptech pads and Brembo rotors get here. I took a scotch brite wheel to the rotors again to get the gross shipping coating thats on them, and then got everything installed. Greased everything, did new rear pads as well (rear rotors were fine). Bled them, and took it for a drive. After bedding them in and using the same procedure I've used before and on my car (2006 with Brembo's, stops fantastically), NOTHING HAS CHANGED. And the driver rear caliper was smoking after the initial bed in process lol. What...da...hell...

    I should also mention that the car absolutely DESTROYS the front rotors after a weekend of drag racing. It has 700 whp so it hits decent speeds, but the rotors look like a Dalmatian puppy with the hot spots all over the surface. It eventually slows the car down, but I really feel like it should have way more braking force than it does.

    Any ideas? Have two race events these next weekends with it where it'll be exceeding speeds over 160 mph and I am scared to drive this death trap.
     
  2. 07TGGT

    07TGGT @user

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    Are the brake lines the original factory lines? If the rear is smoking after the bed in process I would say you have a sticking caliper. I'm not really sure what else could be causing the issue(s), but possibly a faulty master cylinder.
     
  3. Speedboosted

    Speedboosted Found missing cylinders

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    Yes, original lines. Car has 62k on it. And as much as I would like to think I didn't mess up because I've done S197 brakes countless times, I have to wonder if I screwed up somehow on that caliper. It had been fine before that. I noticed while bleeding it that it flexes a lot while the brake is being pumped, is that normal?

    The master cylinder came to mind as well.
     
  4. Pentalab

    Pentalab forum member

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    Get it sorted out b4 you wind it up to 160 mph. If a caliper locks up, you could end up flying off the track. Are you using SS brake lines ?
     
  5. Speedboosted

    Speedboosted Found missing cylinders

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    Well duh lol. And no, stock brake lines. The more reading I do, the more I think it is the brake master cylinder is faulty. Would explain why all my attempts to fix it aren't working at all.
     
  6. 07TGGT

    07TGGT @user

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    It's more than likely to be the issue. I would swap out the factory lines for a set of braided SS lines. Especially if you will be tracking the car. SS lines don't expand line rubber lines under pressure and will give you more consistent braking, as well as a slight increase in clamping force.
     
  7. Speedboosted

    Speedboosted Found missing cylinders

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    I've got stainless lines on my car, and the difference I noticed after swapping isn't the feeling that is the problem with the Shelby. Going to steal the master cylinder and rear calipers off my parts car today and see if that solves it.
     
  8. Candy10

    Candy10 forum member

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    ABS module could be at fault if you are getting uneven pressure at each corner.
     
  9. Speedboosted

    Speedboosted Found missing cylinders

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    Wouldn't a code or message pop up for that?
     
  10. Candy10

    Candy10 forum member

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    You would think so, but Im going through some things right now (not brakes), with no codes. These cars are smart when they want to be.
     
  11. Speedboosted

    Speedboosted Found missing cylinders

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    Well I think I overlooked a major point...didn't even notice how shiny the rotors are even after scuffing them up with the scotch brite. You can count the threads on the wheel studs in the reflection off the rotor lol. I'm going to assume the rotors are glazed over and not letting that surface layer from the pad get laid down. The car is stopping ever so slightly better now, so going to put some more miles on it and try to get the layer laid down. If nothing changes, time for fresh rotors and go from there.
     
  12. 01yellerCobra

    01yellerCobra forum member

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    Years ago I had a 94 Trans Am. I took the rotors in to have them turned and when I went to pick them up the machinist asked exactly how fast do I drive. Apparently I had hardened the rear rotors from heating them up. The cutting bit just skipped over the surface. I ended up getting new rear rotors.