My 2003 Saab 9-3 recently failed inspection due to spongy brakes. I didn’t think they were that bad - a little soft maybe - but I figured it was possible I didn’t notice because the change was gradual. I assumed the culprit was the master cylinder, so I replaced it (thank you GM for making the simple task of removing two nuts difficult) and flushed the old fluid.
I didn’t notice a whole lot of improvement, but the car stopped well enough. Not like new, but well enough I thought. Unfortunately, the inspector didn’t think so, and he failed it again.
I took the car home and re-bled the brakes, and there wasn’t much change. Then I did the same test as the mechanic. He accelerated for about 20 ft then slammed on the brakes. He then let the car roll about 10 feet and slammed on them again. When I replicated the test, I noticed that for the second stop the brake pedal was good and firm, but the car rolled 5-10 feet further than it should have. After slamming on the brakes the first time, I couldn’t get the car to come to a jerky stop shortly afterward.
I didn’t bench bleed the master, which I didn’t realize until after I had it back in place. At that point I figured it was easier to just bleed the air out of the system (I was going to do a complete flush of the old fluid anyway) than to remove the new cylinder, bench bleed it, and re-install. Wouldn’t the full system flush remove any air that would have been in the master?
A brake hose (or hoses) might be bad. They’re original equipment as far as I know, which makes them 10 years old. But wouldn’t that mean the brakes would be spongy all the time? Why would the second stop be so much worse than the first?
I read something about vacuum hoses for the brake booster, but there was a lot of jargon and I couldn’t make heads or tails of it. I’m not lucky enough for this to be as simple as replacing a vacuum hose.
Does this have something to do with the anti-lock brake system? Do the brakes need a few more seconds to recover after the ABS has been triggered?
Anyone have any ideas?