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07-26-2009, 03:07 PM | #1 |
Drives: '08 Bayou Blue LB AT Join Date: Oct 2008
Location: West Hills, CA
Posts: 2,517
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Anyone have their brake pedal go rock hard on hot days?
I first noticed this on a hot day while autocrossing and thought it was brake fade.
I've since swapped in SS brake lines, a high performance set of rotors, and high performance pads. (this was done for the autox, not the hard brakes). Now that summer is here, I'm getting the symptoms again. My mechanic filled the system with the ATE Super Blue brake fluid so I don't think the heat is affecting the fluid. I'm sure that if I take the car in to the dealer, they'll blame these aftermarket parts so I'll go back to my mechanic. Thanks in advanced.
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aFe Intake | Blitz Supercharger | Megan Header | TRD Exhaust | NST Pulley Set TRD Shocks/Struts | Tanabe NF210 Springs | TRD Sway Bar | Motegi TRAKLITE wheels | Kuhmo Ecsta XS R1 Concepts slotted rotors | Carbotech 1521 brake pads | stainless steel brake lines | Seibon vented carbon fiber hood |
07-26-2009, 06:06 PM | #2 | |
Quote:
Sounds like Vapor lock, too me . Brake fluid boiling , |
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07-26-2009, 06:20 PM | #3 |
Drives: '08 Bayou Blue LB AT Join Date: Oct 2008
Location: West Hills, CA
Posts: 2,517
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The DOT 4 racing brake fluid is supposed to stop the brake fluid boiling. I'll have to check to see what could be the cause of vapor lock.
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aFe Intake | Blitz Supercharger | Megan Header | TRD Exhaust | NST Pulley Set TRD Shocks/Struts | Tanabe NF210 Springs | TRD Sway Bar | Motegi TRAKLITE wheels | Kuhmo Ecsta XS R1 Concepts slotted rotors | Carbotech 1521 brake pads | stainless steel brake lines | Seibon vented carbon fiber hood |
07-27-2009, 03:18 AM | #4 |
Learn to Relax
Drives: 2007, Meteorite, LB Join Date: Dec 2008
Location: Anaheim, CA
Posts: 2,070
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Vapor lock applies to fuel lines. When fuel lines run close to the exhaust manifold or near the exhaust pipe, the gas will boil and instead of liquid gas, just vapor would feed the carb.
Long, you're not giving enough information to make a diagnosis. It could be that before you had air in the lines and now you don't. |
07-27-2009, 10:50 AM | #5 |
What?
Drives: 2007 Yaris LB Join Date: Nov 2008
Location: Safety Harbor, FL
Posts: 1,006
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I've had that problem. I generally chalk it up to pad fade. It's not fluid fade. The pedal goes mushy when your fluid boils. What you're describing (and what I sometimes feel) is that you're giving the pedal a good firm push... the pads just aren't biting. Pad fade.
It just happens so rarely for me that I haven't bothered to change out my pads yet! |
07-27-2009, 01:27 PM | #6 |
Banned
Drives: 2007 4 Door Yaris Join Date: Jan 2009
Location: Southern California
Posts: 1,357
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^^ I agree, and its not air in the line or it would be constantly crappy.
Have you converted your fog lights to brake vents yet? :D |
07-27-2009, 05:41 PM | #7 |
Or you could put on some nice , well vented Alloy's
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07-27-2009, 09:56 PM | #8 | |
Drives: '08 Bayou Blue LB AT Join Date: Oct 2008
Location: West Hills, CA
Posts: 2,517
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Quote:
I wait 10 seconds, pump the brake pedal and then it depresses and I feel the brake pads bite like normal. It's almost like something is getting under the pedal and I just can't push it hard enough to slow down. I'm not too cool about this because it could happen at a bad time.
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aFe Intake | Blitz Supercharger | Megan Header | TRD Exhaust | NST Pulley Set TRD Shocks/Struts | Tanabe NF210 Springs | TRD Sway Bar | Motegi TRAKLITE wheels | Kuhmo Ecsta XS R1 Concepts slotted rotors | Carbotech 1521 brake pads | stainless steel brake lines | Seibon vented carbon fiber hood |
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07-27-2009, 09:58 PM | #9 |
Drives: '08 Bayou Blue LB AT Join Date: Oct 2008
Location: West Hills, CA
Posts: 2,517
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I've got the ten feet of RV sewer hose. Just need to get down there and cut the foglight inserts.
I'm slow that way.
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aFe Intake | Blitz Supercharger | Megan Header | TRD Exhaust | NST Pulley Set TRD Shocks/Struts | Tanabe NF210 Springs | TRD Sway Bar | Motegi TRAKLITE wheels | Kuhmo Ecsta XS R1 Concepts slotted rotors | Carbotech 1521 brake pads | stainless steel brake lines | Seibon vented carbon fiber hood |
07-27-2009, 10:11 PM | #10 |
What?
Drives: 2007 Yaris LB Join Date: Nov 2008
Location: Safety Harbor, FL
Posts: 1,006
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Hmmm... that IS strange. I've only experienced it at the track and sometimes at an autocross.
Maybe you have a vacuum leak and are losing boost? |
07-27-2009, 10:12 PM | #11 |
What?
Drives: 2007 Yaris LB Join Date: Nov 2008
Location: Safety Harbor, FL
Posts: 1,006
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Wait... you're supercharged, aren't you? Supercharged cars often have problems with vacuum... hard to have vacuum when you have boost! Look into it. You may need to add an electric vacuum pump.
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07-27-2009, 10:17 PM | #12 |
Drives: '08 Bayou Blue LB AT Join Date: Oct 2008
Location: West Hills, CA
Posts: 2,517
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Ok, but the first thing I looked at was my vacuum gauge and was showing good vacuum. I'll have to find where vacuum is going to the brake system.
__________________
aFe Intake | Blitz Supercharger | Megan Header | TRD Exhaust | NST Pulley Set TRD Shocks/Struts | Tanabe NF210 Springs | TRD Sway Bar | Motegi TRAKLITE wheels | Kuhmo Ecsta XS R1 Concepts slotted rotors | Carbotech 1521 brake pads | stainless steel brake lines | Seibon vented carbon fiber hood |
07-28-2009, 11:20 AM | #13 |
ULTIMATE
Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
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There is a vacuum check valve on the brake booster. If that valve fails it will cause the pedal to become mighty hard. You can unscrew it from the booster and blow in either side to see if it is OK.
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