brake levels

[twofst4u]

Just wondering if anyone had noticed the brake pedal, when depress the first time it's low then the second time it's a bit higher. I'm not sure if this is the ABS or just g35 feature.
Modified by twofst4u at 3:50 PM 12/12/2006

[Q451990]

Do you mean just on the first time you press them after starting and moving the car? If so, you may be feeling the ABS self-test. It'll sound and feel kind of like a "crunch" in the brake pedal. I find that it's more pronounced in cold weather.

If you mean every time you press the brakes - you're having a low pedal the first time - that does not sound normal. That's a classic sign of air in the lines. Could have gotten there during brake bleeding, or from some sort of defect.

Heath

[twofst4u]

I'll have it check...it definitely not the crunch sound ABS self test. It's the first time you hit the brakes, then you pump it again the pedal is definitely a little bit higher. But the car is only 2months old. I hope it's not major.

[C-Kwik]

Anytime you pump the brakes, the pedal will become stiffer and engagement will be higher. Master cylinders work by revealing an orafice to the reservior when the pedal is released. But if you release the pedal and then push it in again quickly, the negative pressure in the lines when releasing the pedal will pull a small amount of fluid into the cylinder from the reservior. When you quickly depress the pedal again, you won't give the system a chance to equalize the pressure and you'll force more fluid into the cylinder than before, which raises the engagement point. This is why you're instructed to pump the pedal if you ever lose pedal pressure. You can actually get some braking if you force some additional fluid or air into the lines if you should ever have too much air in the lines or perhaps a leak.

Try pressing and releasing the brake, then wait 10 seconds or so and do it again. It should have the same pedal engagement height.