I was driving my girlfriends Ford Fiesta last week and it started to experience brake fade.
It always happened after driving the car at higher speeds over 100kmh (60 MPH). The brake pedal became spongy and there was a diminished braking effect. I noticed the left rear wheel heating up, so I guess the left rear brake is not releasing completely.
After reducing traveling speeds, driving at around 70kmh (around 40MPH), brakes become responsive again and sponginess went away.
This leads me to think that the left rear brake is scraping and at higher speeds causing heat to build up which boils the braking fluid. So I scheduled the car for brake fluid replacement and a brake inspection to determine why the brakes are scraping.
The guys at garage saw the rear braking cable was damaged and said that the braking issues came from the brake cable. I am not saying braking cable couldn't cause this problem, but I doubt it, and they haven't opened the drums to see why the shoes don't fully release.
I asked them to just replace the brake fluid and see how that works but they refused. They said that I either replace the brake cable or go elsewhere.
Was I right, or wrong? I think they want to fool me and I don't have money for repairs that are not completely needed.
I still think its suspicious as the high temp was causing the fading and it wasn't something permanent like a broken brake cable.