I need some help with a chronic brake problem. I have a 2000 Mustang GT convertible with 78K miles. Many years ago I had problems with the front brakes dragging and heating up the front rotors and the entire wheel. I swapped the pads and calipers out, which seemed to address most of the issue. There was much less drag, but still a little. After that, I gave the car to a family member who only put about 3K miles on it over 11 years. I now have the car back again and discovered the brake drag problem was really bad again with the front wheels heating up. Rotors near 200F after a 5 mile drive - and I even downshifted and used the parking brake to stop the car. I went ahead and swapped pads and calipers again, which yielded some improvement, but after driving on the freeway and never touching the brakes, it still has the rotors running at 110 - 120F, so they are definitely still dragging a bit. I also have the brake dust to prove it.

My next step was to swap the master cylinder. When I removed it, I noticed some staining on the backside, showing that it was probably leaking a bit. I went ahead and purchased a brand new one - the car quest brand - and did the bench bleed. After 2 days of manually pressing the cylinder in, I felt satisfied that I had bled every last bubble out of it. The piston would only depress about 1/8 inch with good force on it. Next, I installed in on the car and bled the system at every wheel from the furthest away to the closest. My method was a 15 year old kid pressing the pedal until I pushed enough new fluid through each one to ensure no bubbles and that I had nice new light colored fluid coming out of my clear bleeder hose. So it was essentially a total fluid change.

Here's what I have now: The brake pedal still feels spongy and goes in too easily for a few inches before good braking begins. It acts as though I've still got air in the system somewhere after I've pumped about a quart of fluid through everything already. The front brakes still have a little drag on them, so perhaps some improvement, but certainly not freewheeling like it was new. What ideas do you have for me?

 

hoses or proportioning valve

 

Replace ALL the hoses. They turn to cheese when they age.

 

thus accumulating in the calipers

 

+1 on hoses. They’ve likely partially collapsed internally causing the drag. Watch this first…it is an excellent tutorial for diagnosing your problem.

 

Def an interesting video...specially around the 0600 minute mark.

 

I hear you on the hoses...but they're new. At least the ones on the front. I changed them when I changed the calipers and pads. The ones on the back might need a swap to be safe. The back ones aren't dragging though, so it would seem a little weird if that were causing any dragging on the fronts. As for the soft pedal, I'm going to bleed the ABS and see if I get more air out of the system. Seems strange that it would have gotten air in it since I bled the master cylinder very well, but who knows...

 

Here's an update on this issue. I used a Foxwell 510 scanner with the ABS bleed function to successfully bleed the brake system. I went through the procedure twice and had a much better pedal, but I'm still feeling a little too much travel before brake engagement - a softer start than I remember this car having. On a good note, I'm not having any more brake dragging going on, so I've concluded that the master cylinder was the culprit. I'm going to run the procedure a couple more times and see if the pedal gets any better. The trapped air bubbles are tiny and don't escape very easily. I have a couple of lessons learned to share as well. First, there are two master cylinders available for these cars. One is for ABS and the other is for a non-ABS car. I thought they all had ABS, but apparently not. The difference is that one of the master cylinder outlet ports is larger than the other on the ABS version. The non-ABS master cylinder has two outlet ports that are the same size. The second lesson is that the Foxwell scan tool will do the job but the instruction sheet that comes in the box is useless. Download the full manual from their website. You'll have to connect the scanner to WIFI And download the Ford software. The special function for ABS is in the main Ford software file. You don't need any other special file to access that function.