soft brake pedal

[Michael Saul]

2008 Mustang GT, manual transmission, 18,000 miles, soft brake pedal.
I discovered the soft pedal about 75 miles into a 150 mile drive through Trinity County, California. When I got home I replaced the master cylinder. Did my best to bleed it before putting it on the car. Then I pressure bled the calipers. No change or improvement in brake pedal feel. No ABS warning on dashboard. Suggestions?

 

[rocknrod]

Have you change anything before this like the calipers? - https://www.speedwaymotors.com/the-...cylinder-bore-size-on-your-brake-system/30895

 

[Michael Saul]

Thank-you for your response. Calipers are original. I have pressure bled them every year, despite very low miles. When new I changed the driveshaft for a one piece one, air box, subframe connectors, some other things.

 

[Samos3]

One or more calipers could be sticking on their slides.

 

[DieHarder]

Might want to check the vacuum hose for leaks (between the brake booster and intake manifold). Be care with the hose connector that plugs into the brake booster; it's plastic and can be easily damaged attempting to remove it but difficult to find anymore so be careful with it.

If no leaks and brake booster is good you might want to consider upgrading to Brembo 4 puck calipers and steel braided brake lines. Just order replacement calipers/rotors/pads for a 2008 GT500. Cost is low and the improvement is worth the $500 to upgrade. Most any autoparts store carries them. Got mine from O'Reillys.

 

[Michael Saul]

Again, I thank-you for your responses. I will examine the items you listed.
Thanks again, MSaul

 

[Michael Saul]

Booster bad.

 

[brasil]

..a bad booster causes a HARD pedal.. on poor braking performance.

I would take a closer look ...at the brake hoses. The now 18 years old rubber hoses often are swollen. This causes a soft pedal ( first ) and there after o total loss of the brake circuit.

..Also possible - at the time when you changed the MC perhaps...some air went into the ABS Block. This causes soft brakes too.... The get rid of the "air " inside the ABS Block you need a scanner..

Hope this helps

 

[Michael Saul]

Thank-you for your recommendations Mr. brasil.
Stainless steel brake lines are my next project.
The ABS light did not come on with my MC replacement, but I expected it to, as fluid was running freely from the MC as I positioned it and attached the brake fluid lines.
This MC was the most difficult I have ever replaced.

 

[MasterofDisaster]

I installed braided stainless steel lines a couple years ago. Love 'em.

Be careful about the banjo bolt torque in the rear.

 

[Michael Saul]

Okay.