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Post by nfsp350z on Feb 13, 2012 19:59:27 GMT -6
So yesterday, my 5th & 7th runs I had brake failure. I was on the limiter comming up to the last turn, I stabbed the brakes for the last corner but nothing. Brake pedal seemed to have standard travel but no stopping force. On the 7th run I let off and reapplied a few times but had to pull the hand brake. Before that no problems, 6th run no problems, on the way home no problems. Any ideas?
BTW, the car is 04 350Z Enthusiust 64,000miles, StopTech slotted rotors, Hawk HP Plus pads, newer high performance fluid (dont remember brand).
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Post by Ninelives17 on Feb 13, 2012 20:31:12 GMT -6
Check vacuum line going to brake booster, then check valve in line, and then the brake booster itself. If you really STAND on the brakes they should work, just no power assist.
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Post by jessew on Feb 13, 2012 20:37:42 GMT -6
sounds like you boiled the fluid. I've had the same problem in the mustang making half mile top end runs back to zero
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Post by Ninelives17 on Feb 13, 2012 20:42:56 GMT -6
Boiling the fluid would put air in the lines, he would have no pedal instead of a hard pedal.
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Post by jessew on Feb 13, 2012 20:48:49 GMT -6
Fade then?
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Post by Ninelives17 on Feb 13, 2012 20:56:18 GMT -6
Fade usually comes from boiling the fluid
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Post by Ninelives17 on Feb 13, 2012 21:04:05 GMT -6
Either his motor isn't producing enough vacuum, or he has a vacuum leak. The leak is far more likely. Unless he has drastically modded his motor
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wes
Junior Member
Posts: 60
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Post by wes on Feb 13, 2012 21:27:31 GMT -6
ABS icing? The turboed cobalts have this issue. Vacuum related going from full boost to max braking.
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Post by nfsp350z on Feb 13, 2012 21:30:41 GMT -6
No fade. Fluid was not boiled. Motor has intake manifold & short ram intake. I will have to start checking lines first it sounds like. thanks.
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Post by nfsp350z on Feb 13, 2012 21:33:56 GMT -6
ABS icing? The turboed cobalts have this issue. Vacuum related going from full boost to max braking. Im not boosted but I wondered if this was relevent. I was going straight from full throttle rev limiter to full breaking each time.
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Post by Ninelives17 on Feb 13, 2012 22:41:15 GMT -6
Engines produce the most vacuum at low rpm, at high rpm they make hardly any at all. This is where the check valve comes into play. The check valve enables you to "store" vacuum until you need it for brakes. You could have a tiny hole in either the check valve or the booster. I'm far from an expert but I do work on my own cars. there might be a mechanic on this forum that can chime in.
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Post by DAN on Feb 13, 2012 23:37:02 GMT -6
Doesnt it have a vacume canister to store vacume.
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Post by primaris on Feb 13, 2012 23:59:20 GMT -6
I can think of only two possibilities for what you describe: Fade or no vacuum. Fade is when the pads are too hot. It has nothing to do with fluid temp. The pedal will feel normal, but you are not getting the same amount of deceleration as you should. No stored vacuum. You have brakes but the pedal is hard as a rock. This is my vote on what was happening to you. You were full throttle so no vacuum was being made and you used it up in the previous brake zone. Or, your check valve is bad. Just pull it off and suck air through it from both sides. Here is about as good a definition for brake fade as I could find: www.elephantracing.com/techtopic/brakefade.htm
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Post by DAN on Feb 14, 2012 0:45:04 GMT -6
No vac would = extremely hard to depress peddle,After re-reading your post I didnt see that in the description and you said it had normal travel. So I have to agree with Jeff. However with the set up you have fade doesn't seem like the right answer. My question is how did you bed the pads in, I have read a few articles on hawk pads and most pointed to bedding them correctly was very important.
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Post by Ninelives17 on Feb 14, 2012 10:29:37 GMT -6
As the tech article stated, boiling the fluid is directly related to fade. they claim street pads to be good to about 700 degrees, but clean DOT 3 fluid is only good to about 340 degrees with the exception of Motul and others which can handle about 650. Dirty or fluid with moisture will be significantly less I know the pads get hotter than the fluid, but I've always heard fade caused by boiling fluid to be far more common. Either way I think we all agree this is not his problem, and that he has a vacuum related problem
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