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Old 09-08-2014, 10:06 AM   #1
Cooleronie
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Unhappy Sudden brake failure that caused an accident, how?

Hello!

I apologize if this thread is misplaced, as you can see I am new.

So here it is. I was driving in my friends car going max. 30mph (50km/h) when I had to slow down / stop for a car in front of me. Just like any other situation I geared down and slowly applied my brake pedal. But the car barely braked at all! It was when I pressed the pedal even further I finally got some brake power. At approximately the same moment I felt my car slip and I steered to the left to avoid an accident, but I still (back-) side hit him.

Two things. First, there was only one tire slip (?) on the road and that was from (probably) the front-left tire. Second, the car seemed to be braking just fine somewhat an half / hour later. It was then carried away to undergo a technical inspection which I have not heard from yet.

Is there any way this could have technically happened, and if so, how?

Info:
- Car: Seat Toledo TDI ('98).
- The car had a few brake lines (pipes?) replaced about a few weeks / month ago.
- From what I can recall (it happened in a few seconds) the brake pedal was lighter than usual, but got heavier at the end (but not like I am used to).
- I have not yet got the inspection results back, but since the brakes worked again I doubt they'll find something.. ?

Thank you!
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Old 09-08-2014, 01:23 PM   #2
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Re: Sudden brake failure that caused an accident, how?

Since you mention you geared down, I'm assuming this is a manual transmission vehicle. And, since you mention it was a friend's car, I'm further assuming you are not real familiar with this car.

Based on the two above assumptions, is there a chance that you stalled the engine in the process and that's why the brakes did not work as you were expecting? Was the steering also harder than usual, contributing to what you think might have been slipping? What about the weather or the road surface leads you to think a wheel might have slipped?

-Rod
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Old 09-09-2014, 03:30 AM   #3
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Re: Sudden brake failure that caused an accident, how?

Thank you for your response.

The engine did not stall when it happened. I had plenty of time to decelerate and it was a regular situation I was in (so no rush), it was only when I started to hit the brakes I noticed I barely had any braking power whatsoever. So I pushed the pedal further down, with more force, (probably) causing the front tire to slip, but this was just before I steered away. This is confirmed by the stripe on the road (little straight, then to the left). The road was dry as well as the weather.

The reason I was asking in the first place is that I am somewhat baffled by how this could technically happen..

Edit: Oh, and I was comfortable driving the car, was definitely not the first time. And yes, it is a manual.
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Old 09-09-2014, 07:36 AM   #4
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Re: Sudden brake failure that caused an accident, how?

Quote:
Originally Posted by Cooleronie View Post
This is confirmed by the stripe on the road (little straight, then to the left). The road was dry as well as the weather.
By this are you referring to a skid mark left in the road by the rubber from a tire sliding across dry pavement? If so, that would suggest the brakes were working well enough to lock up, at least for one wheel. Does the car have ABS?

-Rod
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Old 09-09-2014, 07:55 AM   #5
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Re: Sudden brake failure that caused an accident, how?

Yes, I meant a skid mark. It is not that long (like 1 car - 1,5 car long) and it felt like when I finally got some (but still not much) braking power it immediately started slipping. Apparently only the left front wheel, that is. If you would like to have a picture of it, just let me know.

The car has no ABS.
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Old 09-09-2014, 11:25 AM   #6
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Re: Sudden brake failure that caused an accident, how?

could be a failure of several components, if power booster fails brake pedal responce will be much harder to get car to stop. may also have a frozen caliper or wheel cylinder. i would suspect the power booster failed but they can look over the whole system for a issue
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Old 09-14-2014, 01:48 PM   #7
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Re: Sudden brake failure that caused an accident, how?

Hi, Cooleronie!

Sorry to join in late; I'm not familiar with Seats, but if a tandem master cylinder fails internally or runs low on fluid in a car with diagonal hydraulic circuits (rather than front/rear circuits), what you described can happen. Loss of one circuit's pressure will almost double the pedal travel needed to pressurize the other circuit.

Did you say that the brakes resumed working later?
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