Very, very strange problem. Brakes applying themselves, and holding. WTF?
#1
08-10-2009, 12:15 PM
Very, very strange problem. Brakes applying themselves, and holding. WTF?
I have a brain stumper. We have not run into ANYONE with this problem on a G/Z.
'04 Coupe, Brembo's.
Basically, my car builds pressure on the brake system after driving it. Idling it builds a tiny, tiny bit. Not terrible, but noticeable. Enough to know that vacuum hasn't released.
But when you drive it, and get a half mile or so it's almost as if you have the brake pedal 1/3 of the way down. I mean, you let off the gas and within 2 seconds the car is stopped.
It's the whole system, all four corners. When you pop the vacuum off the brake booster then it releases pressure.
All suggestions, guesses and otherwise are welcome! None of the tech's we've spoken to have never run across this, but most people point their finger to the brake booster. Thoughts?
The story behind it as was posted on another forum by my buddy helping me out:
'04 Coupe, Brembo's.
Basically, my car builds pressure on the brake system after driving it. Idling it builds a tiny, tiny bit. Not terrible, but noticeable. Enough to know that vacuum hasn't released.
But when you drive it, and get a half mile or so it's almost as if you have the brake pedal 1/3 of the way down. I mean, you let off the gas and within 2 seconds the car is stopped.
It's the whole system, all four corners. When you pop the vacuum off the brake booster then it releases pressure.
All suggestions, guesses and otherwise are welcome! None of the tech's we've spoken to have never run across this, but most people point their finger to the brake booster. Thoughts?
The story behind it as was posted on another forum by my buddy helping me out:
We swapped my coilovers from my Z to a friend's 04 G35 coupe.
Everything went without a hitch last night. Drove home 20 miles with a mix of street and interstate roadways.
This morning, after trying to diagnose a brake light switch issue on my Z by borrowing the switch from the G, the problem arose. (Neither vehicle was turned on while doing this)
The switch that I pulled was the lower switch since there's two switches on the brake pedal assembly which I'm thinking may have been the ASCD switch. (The one that disengages cruise control when brakes are applied.)
^^This switch work may not have anything to do with this as it may be coincidental with timing.
The brake system in the G is building vacuum pressure, but not releasing. It will build pressure on its own or when you press the brake pedal. This is causing the entire system to apply the brakes and stop the car.
This happened as soon as we left the house and we didn't make it but five blocks away. In order to get home, we had to pull the vacuum line to release pressure a couple times on the way back home.
04 G35 coupe, 6mt, with oem brembos that have never been touched and brake lines were not kinked during installation of coilovers.
Does ANYONE have any ideas??
Everything went without a hitch last night. Drove home 20 miles with a mix of street and interstate roadways.
This morning, after trying to diagnose a brake light switch issue on my Z by borrowing the switch from the G, the problem arose. (Neither vehicle was turned on while doing this)
The switch that I pulled was the lower switch since there's two switches on the brake pedal assembly which I'm thinking may have been the ASCD switch. (The one that disengages cruise control when brakes are applied.)
^^This switch work may not have anything to do with this as it may be coincidental with timing.
The brake system in the G is building vacuum pressure, but not releasing. It will build pressure on its own or when you press the brake pedal. This is causing the entire system to apply the brakes and stop the car.
This happened as soon as we left the house and we didn't make it but five blocks away. In order to get home, we had to pull the vacuum line to release pressure a couple times on the way back home.
04 G35 coupe, 6mt, with oem brembos that have never been touched and brake lines were not kinked during installation of coilovers.
Does ANYONE have any ideas??
#2
08-11-2009, 08:25 AM
Todd, I would also check the one way valve that is located on the passenger side of the motor in the S shaped hose to see that it is functioning correctly. I know if you but it backwards no vac can get to the brakes, causing a no brake feeling... I would just give it a look that is a much cheaper fix than the booster.
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