Brake Failure.......

teulk

teulk

teulk

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Bit of history first........For a few months now the right hand caliper had been sticking and binding and causing some heat and squeeks and squeels. Also when braking you only had to breath on the brake pedal and you had whiplash. I removed it, re greased the slide pins (girling brakes) and put them back together and this seemed to solve the problem and allowed it to move freely. Also the car pulled to the left slighlty when braking. Now i managed to free the right caliper up and everything seemed ok as far as that was concerned but it still pulled to the left.........I looked at that caliper but it seemed fine, no binding, no leaks and it moved freely. I did the work on the right caliper on saturday, took it for a test drive and all worked ok, no more binding and no more whiplash....... the car was driven on sunday and covered around 50 - 60 miles on normal roads and motorways so the brakes got well used. Today is Monday and the brakes have just failed and resulted in my g/friend going into the back of another car. She said the pedal just went straight to the floor and nothing happened. The impact was at very low speed, probably around 5mph. I cant help thinking its something ive done thats caused this but im confident when it comes to working on brakes and have done many times. Im guessing its perhaps the master cylinder but ive just checked the car and they work ok now. What could have caused the brake failure and is it something i could have done to cause this or could it just be a coincedence ?

The pedal does not sink to the floor when pumped with either the engine on or off. The car is a 1999 Renault clio RXE
 
doesnt make sense... she said that it goes to the floor when it doesnt etc. all i can imagine was that after moving the caliper around a bit you may have damaged the brake line if it was old etc but if it had split, you wouldnt have any pressure.

maybe she just wasnt used to not having whiplash brakes and just went into the back of it
 
Hmm, without wishing to cast aspersions, are you sure that your GF is giving you the facts i.e. she didn't just have a lapse of concentration?

It would be most unusual to have complete brake failure that instantly rectifies itself. The pedal sinking to the floor with no braking effort being applied would point to a seal, or pipe failure somewhere in the system, but even then there are two independant circuits, and have have both fail at the same time would be very unfortunate indeed. Is the fluid level normal?
 
I trust my g/f and what she say's..........im a bit baffled too but i have thought the same about the leaks and seals - the brake hoses look to be in really good condition. I had a quick look and i cant see any leaks anywhere. Is it possible that this is a cause of what ive done - but why does the fault disapear as quickly as it happened......????? Could the master cylinder indeed be a fault ????? Yes the fluid level is ok
 
the master cyl can die, they often die slowly, but if they die to the extent that it just goes to the floor its unlikely (ie not really possible) to 'just come back to life' and hold a solid pressure
 
Maybe the brake is still binding and overheating, boiling the fluid and resulting in brake fade?

Now it's cool again, it all seems to be working.
 
even if it was the master cylinder and it went the pedal went to the floor, she would have pumped the pedal again (natural reaction) and it would have braked..

Fluid levels ok.
Brakes ok.
Pipes ok.
No Leaks.
Pads still in their carriers.

Points to your GF i'm afraid.

Edit: even if the brakes were faded on the front the rears would have stopped it at 5mph!
 
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volospian said:
Maybe the brake is still binding and overheating, boiling the fluid and resulting in brake fade?
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A reasonable theory, but the brakes would have been *stinking* by that stage, and probably smoking a fair bit. Assuming the brake fluid isn't 99% water of course...
 
As everyone else, I can't think of any brake faults that would result in complete brake failure and then rectify itself.
things like brake fade and reduced braking, but not complete brake failure.

Did she hit the clutch by mistake.
 
Matt82 said:
i thought that too (the clutch one) but thats a massive boo-boo to make lol
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at the moment That's the only thing I can think of, the accelarator would be obvious of you did that.

there's no leaks in the system, which means what ever happens you're almost certainly get some braking power.
 
Dogbreath said:
A reasonable theory, but the brakes would have been *stinking* by that stage, and probably smoking a fair bit. Assuming the brake fluid isn't 99% water of course...
Click to expand...

Yeah, but, like others, I can't really think of anything that may cause a failure which seems to rectify itself.

My initial thoughts are user error, but I posted fade as a possibility.
 
volospian said:
Yeah, but, like others, I can't really think of anything that may cause a failure which seems to rectify itself.

My initial thoughts are user error, but I posted fade as a possibility.
Click to expand...
very unlikely to affect the rear brakes though, so the pedal would still have resistance.
 
volospian said:
My initial thoughts are user error, but I posted fade as a possibility.
Click to expand...

And I totaly agree it's got to be one of the very few scenarios that could actualy cause the events describes by the OP. I would think that burning smells and smoke are just the sort of things a concerned female driver would be keen to report however.

AcidHell2 said:
very unlikely to affect the rear brakes though, so the pedal would still have resistance.
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That said a single circuit failing will make the pedal sink much lower than it does normaly, so it could be possible to think that the pedal was "hitting the floor" in the heat of the moment, even if it actualy wasn't.

However I am still somewhat dubious that any fault actualy exists...
 
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AcidHell2 said:
very unlikely to affect the rear brakes though, so the pedal would still have resistance.
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Yeah. Although we are all assuming that the pedal did indeed have no resistance at all. Just because she said "oh, it went flat to the floor, nothing there" doesn't mean that's exactly what it did (no offence intended).

Dealing every day with users makes me somewhat sceptical of claims that they "didn't do anything, the computer just started deleting my files" and so on as, more often than not, technology doesn't suddenly start acting randomly.
 
you have to remember that girls are never at fault, so it would have to be the work the OP has done on it recently ;) (really, im just kidding lol)
 
Dogbreath said:
A reasonable theory, but the brakes would have been *stinking* by that stage, and probably smoking a fair bit. Assuming the brake fluid isn't 99% water of course...
Click to expand...

plus if it had got that bad then it would have a naff pedal now. might have a pedal just not a very good one.
 
possibly air in the sytem? that can sometimes make them need to be pumped before you get any real braking power....
 
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