85 Brake Issue
Thread Starter
Racer
Joined: Aug 2019
Posts: 260
Likes: 94
From: Wilmington, Ohio
85 Brake Issue
I just put on new pads and rotors a few days ago, brakes were bled perfectly. Now, just the last couple days, my brake pedal becomes soft and wants to travel to the floor, if I give it a quick pump it becomes firm again. I checked for leaks as someone pressed the brake pedal and I found no leaks, and the master cylinder was full of fluid. Is it possible the brakes need bled again, even though we were very thorough the first time? I appreciate any input.
Racer
Joined: Mar 2020
Posts: 387
Likes: 148
From: Langton, Ontario, Canada
2025 C4 of the Year Finalist - Unmodified
A bad master cylinder can be identified this way:
Press the brake pedal so that it's firm under your foot. If you let off the pressure slightly, then the pedal will go to the floor on its own. If it's consistently soft, or firm then goes soft after a while, or if you can pump it up, then it's air in the lines.
Check all around the master cylinder for fluid runs on the bottom of the brake booster. Occasionally, it could leak into the booster, but that's rare.
Press the brake pedal so that it's firm under your foot. If you let off the pressure slightly, then the pedal will go to the floor on its own. If it's consistently soft, or firm then goes soft after a while, or if you can pump it up, then it's air in the lines.
Check all around the master cylinder for fluid runs on the bottom of the brake booster. Occasionally, it could leak into the booster, but that's rare.
Drifting
Joined: Aug 2019
Posts: 1,339
Likes: 225
If you're pretty sure they are bled correctly, then I would suspect the master. They can leak internally without any external indication, One dead indication will be to pump up the brakes, then wait....if the pedal sinks slowly, then I would consider the master.
