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-   -   Please Guide Us: How to stop a car that has lost its brakes (https://www.team-bhp.com/forum/technical-stuff/16368-please-guide-us-how-stop-car-has-lost-its-brakes.html)

can some one guide me as to how to stop a vehicle if the brake have failed and its an automatic transmition ?

Edit...

Errr, since you have lost brakes and even the handbrake wont work, your best bet would be to take the car off road and get ready for damage control. Shifting the car to lower drives would be off little effect but atleast slow it down a little.

Hi,

Other than the above you can keep pumping the brake pedal. Even if you loose hydraulic pressure the brakes should still work and get your car down to a reasonable speed.

I have unfortunately faced this situation at the speed 90kmph in my 123 series 300D Merc on the lonavala ghat coming down. The stupid driver had overfilled the brake oil which caused loss of hydraulic pressure.

Was only presence of mind, no traffic and experience that saved us from a crash.

Viper

umm? If you lose all hydraulic pressure, there are no forces acting on the pistons pushing them out to clamp the rotor. So pumping the pedal in this case is useless. The only think that would work would be the cable operated hand brake.

Robin,

The brakes will work in the absence of hydraulic pressure for 2 or 3 pumps which should be enough to slow down to a decent speed. Try switching off the ignition and cruise in any car then try braking. The pedal will become hard but with a bit of extra effort will still work. Same as the case for Hydraulic power steering.

Have been in the situation 3-4 times in different cars and that little extra knowledge is what saved the car from a crash.

Viper

hi Team,

i have a question here if no breaks what if we switch off ignition? what will happen.. will the car come to halt if it is not in neutral? if so what this will effect the engine or any other thing?

forgive my ignorance...

Hey Viper,

I think you're mixing up the loss of power assist with the loss of hydraulic pressure. With the former, yes, you will have brakes, but would just loose the booster assist.

Hydraulic loss means that there is a leak somewhere which causes the brake fluid to leak out leaving you with no brakes whatsoever.

Hi,

Am referring to the same situation. Happened to my on my diesel Tata Mobile, Contessa 1.8l Petrol, Esteem. In all 3 situations there was fluid leak. Brakes will work albeit for the first 3-4 pumps only.

Viper

Sure, it would work till the fluid leaks out. But his question was what to do after that, as it would be instinct to keep pumping the pedal till it finally has no further effect.

In a MT, shift to first gear.
In an AT, its more a case of "least damage" rather than stoppage,
One way is to shift the car into "P" or 1/2. Most AT cars have 1/2 for hill climb etc.,
Try to find some bushes or a ditch where the effect of the crash will be minimal. In hilly sections try the hillside if possible. You can always use friction braking. I once lost brakes on the indica due to leak in the rear master cylinder. Combo of first gear, pumping and handbrake saved the day. After that I drove at 10kmph to a petrol pump(which was nearby), purchaed brake oil and that was enough for next morning when I took the car to the workshop.

Hey,

My mistake then I misunderstood the question.

Viper

@Dhananjay - Minimise damage. Thats all you can do in an AT.

Happened to these and your Merc? Man...you need to maintain your cars brakes more often! I have had only one brake failure, and it was more than 10 years back on my Padmini diesel. Luckily I was barely at the speed of 10 km/h.

if anybody does do this make sure that you turn the key to the off position only and not the lock position.

if there is no traffic and you have a fairly long stretch of road then you can get off the throttle and put it into L and use engine braking.

good point made heel, switching off the engine doesn't mean locking the steering as well. that could become very dangerous.
the best bet would be to put the car in 1st gear and find an isolated spot or an uphill & brace urself.

man, i didn't know so many people had such a serious situation with their cars & never told about it here. so far, by god's grace, even with minimum maintenance sometimes, i haven't had that experience. touchwood. no one should never have.

When I was descending from Ooty in a Fiat (1960's model) my father warned me not to shift to first -- he said something like the transmission rod will get broken. Does this apply to modern vehicles as well? Of course in the case of brake failure, one shouldn't worry about such issues-- but it might be difficult to engage first gear at speed, so second might be a safer option.