# Lost all braking, pedal to the floor. minutes later braking fine again...??



## surfo (Jan 6, 2006)

Ok here is the issue explained fast...
2 cars different cars, same problem.
Leon Cupra 1.8T
Subaru Imprezza wrx 2008...
BBK 13" 8 piston
On a track day after 5-6 laps from one turn to the next, braking simply was CERO!!.. and brake pedal went all the way down! pumping it real fast got 20% braking back... so down to pits... no leaks, bleeded again, and off to the track once again...
7 laps later... same problem!!! no spongee pedal feel, no fading, just brake all the way down and no braking with out warning!!!
Both cars have the same issue... more less same number of laps from each other, no leaks, no visual problem..
if Master cylinder fails, it wouln`t recover braking again I suppose? so why we were abble to race several times again, just waiting for it to happen again, and it did... 
Brake pads are for up to 800ºC (1472ºF) and I know (maybe wrong) when pads exceed the working temperature pedal feels spongee and braking is reduced, but never brake goes all the way down and get no braking from one second to the other!!!
Talked to the BBK company and they are "checking" since they have had never this issue so they point to a problem not related to the brake kit..
the most weird thing is that happens exactly the same on 2 different cars/brand/model !!!








thanks!


_Modified by surfo at 10:07 AM 4-26-2010_


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## surfo (Jan 6, 2006)

Bump... !


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## sheetmetal (Dec 1, 2005)

*Re: Lost all braking, pedal to the floor. minutes later braking fine again...?? (surfo)*

Have you solved the problem? If so what was causing this?


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## veedubb7 (Apr 20, 2002)

*Re: Lost all braking, pedal to the floor. minutes later braking fine again...?? (sheetmetal)*

It sounds like your brake fluid is boiling. The temperature rating for your pads is probably higher than the rating for your fluid.


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## GTijoejoe (Oct 6, 2001)

*Re: Lost all braking, pedal to the floor. minutes later braking fine again...?? (veedubb7)*


_Quote, originally posted by *veedubb7* »_It sounds like your brake fluid is boiling. The temperature rating for your pads is probably higher than the rating for your fluid. 

http://****************.com/smile/emthup.gif 
This is the same kit on two different cars/brand/model??? Scary coincidience if you're using race fluid


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## waabaah (Jun 24, 2006)

*Re: Lost all braking, pedal to the floor. minutes later braking fine again...?? (GTijoejoe)*

yeah..technical term is called "brake fade".
dot 3 fluid has a lower boiling point as opposed to dot 4 fluid. good thing that dot 3 and dot 4 are compatiable.
so change your brake fluid to dot 4. 
changing your brake fluid is also mentioned in most (if not all) race events. same pamphlet that says tape headlights, wear helmet, etc..
brake fluid is porus (sic?) meaning that it absorbs moisture. so old brake fluid will absorb moisture which results in a lower boiling point then fresh fluid.


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## surfo (Jan 6, 2006)

well, one car had dot 4 other dot 5 (wich is not recomended for long term use... one car had Race pads, other Street/semi race pads... And we are the ONLY guys with this problem using this BBK... so maybe we left some air on the system? don`t think so, but who knows...
We are re-doing the bleeding process, and although we have no way to really test them until next track day... we will do our best effort!


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## waabaah (Jun 24, 2006)

*Re: (surfo)*

air in the system will present itself on the first application of braking. so if your brake pedal feels good then you should be able to rule this out.
did you do a full system flush before you went racing?


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## GTijoejoe (Oct 6, 2001)

*Re: Lost all braking, pedal to the floor. minutes later braking fine again...?? (waabaah)*


_Quote, originally posted by *waabaah* »_
brake fluid is porus (sic?) meaning that it absorbs moisture. so old brake fluid will absorb moisture which results in a lower boiling point then fresh fluid.

The term you are looking for is "hygroscopic" http://****************.com/smile/emthup.gif


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## surfo (Jan 6, 2006)

*Re: (waabaah)*

For the Subaru, yes... full flush, for the Leon no since fluid had no more than 2 months and was clean... 
Any more ideas?


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## GTijoejoe (Oct 6, 2001)

*Re: (surfo)*

It must be something with the actual parts, its too much of a coincidence, ..... and sometimes companies lie or other's are not using the products in the same fashion as you... Something like air in the lines is something that is always there, what you describe is some type of heat concern making things deflect, expand and become uneffective. 


_Modified by GTijoejoe at 1:07 PM 5-1-2010_


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## surfo (Jan 6, 2006)

well... the thing is that there are actually other cars using this parts in the same matter or harder than us... we won`t be abble to try them again in about 3 weeks, so now we just bleed again, and checked all... see what happens...


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