Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 24th March 2011, 16:20   #46
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,057 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by bblost View Post
Please try this at slow speeds in a very controlled environment. ....

... As soon as the steering locks up.
hmm.. not sure you got my point.. I would still prefer to turn off the engine at slow speeds and help the car slow down even more faster. Yes, as long as its steerable, however hard the steering is. With the wheels rolling, most cars 'should' be steerable, even with some effort.

About removing the key, you serious?

Quote:
Originally Posted by shankar.balan View Post
As far as possible in these situations it is sensible to bang on the emergency flashing lights

..
Along with that, I would like to add 'honk' whenever you manage to free up your hand.
Quote:
Originally Posted by Gansan View Post
This thread reminds me of a person from my middle school days in the 70's.
Motoring was an entirely different 'thing' those days. Not that I've seen the 70's but even in the 80's things were not so different.
dhanushs is offline   Reply With Quote
Old 24th March 2011, 17:45   #47
Senior - BHPian
 
Join Date: Apr 2008
Location: Dombivli
Posts: 2,627
Thanked: 1,191 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by dhanushs View Post
hmm.. not sure you got my point.. I would still prefer to turn off the engine at slow speeds and help the car slow down even more faster. Yes, as long as its steerable, however hard the steering is. With the wheels rolling, most cars 'should' be steerable, even with some effort.
I don't understand how switching off the engine can help in this situation. You lose the power assist on everything, including brakes and steering. Plus when the engine isn't spinning, you also lose engine braking. On a descent this will be extremely dangerous as your brakes have failed and you can't downshift to slow down. Why would you want to recommend that??
honeybee is offline   Reply With Quote
Old 24th March 2011, 18:46   #48
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,057 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by honeybee View Post
I don't understand how switching off the engine can help in this situation. You lose the power assist on everything, including brakes and steering. Plus when the engine isn't spinning, you also lose engine braking. On a descent this will be extremely dangerous as your brakes have failed and you can't downshift to slow down. Why would you want to recommend that??
I apologize for not communicating clearly.

"Switch the engine off when its still in gear."

A non-firing engine will create more engine braking than a firing one. And.. as mentioned above, the brakes are already not working, so no point in assisting them, and as for steering, as the speed is low, even if its 'hard', the response will not take you by surprise.
dhanushs is offline   Reply With Quote
Old 24th March 2011, 21:35   #49
Distinguished - BHPian
 
libranof1987's Avatar
 
Join Date: Sep 2010
Location: All over!
Posts: 3,742
Thanked: 2,872 Times
Default Re: What to do in case of Brake Fail !!

I feel switching off the engine while in motion is one of the most dangerous things to do.

The steering wheel will lock; what then?! Even if one does manage to ensure the steering doesn't lock, the wheel will be terribly hard to maneuver. And in that state of panic where a second misplaced could be disastrous, loss of steering power will make matters worse.

I feel it would be much more helpful if the driver manages to downshift as quickly as possible and then either scrape the sides or pull the handbrake. Again, surrounding traffic will play a huge role in how one goes about it.

I'm curious - to what extent will zig-zag driving cut down stopping distance. I feel a lot would depend on the speed. If the speed is considerably high >40 km/hr, doubt driving zig-zag will reduce the speed of the vehicle significantly.
libranof1987 is offline   Reply With Quote
Old 24th March 2011, 21:41   #50
RGK
Senior - BHPian
 
RGK's Avatar
 
Join Date: Feb 2010
Location: DPM and CHN
Posts: 1,355
Thanked: 206 Times
Default Re: What to do in case of Brake Fail !!

All folks have clearly highlighted what to do in these severe conditions.
I saw one Tempo Traveller driver long back (in 90's) was using downshift always while braking. when I asked him "is this a good practice and will not cost more wear & tear, less mileage" he replied, " I have practised like this only sir and i can stop anytime suddenly as I got the habit of downshifting. Also when you drive vehicles with main axle types (vans, buses) this helps me a lot in safe stopping during emergency situations".

I think downshifting will help to reduce speed drastically and also it is a safe method.
RGK is offline   Reply With Quote
Old 24th March 2011, 22:34   #51
BHPian
 
star_aqua's Avatar
 
Join Date: Aug 2008
Location: BLR
Posts: 612
Thanked: 88 Times
Default Re: What to do in case of Brake Fail !!

All i can say "SWITCH OFF THE IGNITION" then "DOWNSHIFT to lowest possible gear AND DON'T DEPRESS THE CLUTCH then after until vehicle comes to halt"
its a misconception that power assistance will fail. NO it will not until the engine is being driven by the vehicle. The assistance will fail only with EPS(Electric) during key OFF and not with SERVO(Mechanical) Assisted vehicles.

What happens if you don't switch off the ignition: The low idle governor will power the engine and the vehicle will not come to halt immediately.

If your car ignition fuse blows up while driving at a good speed, does it mean very dangerous??
star_aqua is offline   Reply With Quote
Old 25th March 2011, 10:38   #52
Senior - BHPian
 
Join Date: Apr 2008
Location: Dombivli
Posts: 2,627
Thanked: 1,191 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by RGK View Post
All folks have clearly highlighted what to do in these severe conditions.
I saw one Tempo Traveller driver long back (in 90's) was using downshift always while braking. when I asked him "is this a good practice and will not cost more wear & tear, less mileage" he replied, " I have practised like this only sir and i can stop anytime suddenly as I got the habit of downshifting. Also when you drive vehicles with main axle types (vans, buses) this helps me a lot in safe stopping during emergency situations".

I think downshifting will help to reduce speed drastically and also it is a safe method.
With diesels, the downshifting will help reduce speed much faster than petrols. Whenever I drove a diesel Padmini or Uno, I have experienced that the moment I take my foot off the accelerator, the speed drops significantly. With a petrol M800 or the Santro, it is a much lengthier process as the vehicle doesn't lose speed in a hurry.
honeybee is offline   Reply With Quote
Old 25th March 2011, 13:01   #53
BHPian
 
Daewood's Avatar
 
Join Date: Dec 2009
Location: Chennai
Posts: 943
Thanked: 223 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by honeybee View Post
With diesels, the downshifting will help reduce speed much faster than petrols. Whenever I drove a diesel Padmini or Uno, I have experienced that the moment I take my foot off the accelerator, the speed drops significantly. With a petrol M800 or the Santro, it is a much lengthier process as the vehicle doesn't lose speed in a hurry.
That must be due to the ECU setting of modern cars.
Even when you take your feet of the pedal in Santro or M800 the engine revs don't come down below a certain rpm. Added to that both M800 and Santro have good low end torque.
Daewood is offline   Reply With Quote
Old 25th March 2011, 13:27   #54
Senior - BHPian
 
mooza's Avatar
 
Join Date: Oct 2009
Location: Bangalore
Posts: 1,056
Thanked: 245 Times
Default Re: What to do in case of Brake Fail !!

Seeing this thread, I feel it is important for me to go through emergency stopping drills on open stretches of road, with both engine ON and engine OFF, so as to not develop panic when the actual situation does arise, if ever.
mooza is offline   Reply With Quote
Old 25th March 2011, 15:25   #55
BHPian
 
Sprucegoose's Avatar
 
Join Date: Jan 2006
Location: Mumbai
Posts: 311
Thanked: 38 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by Daewood View Post
That must be due to the ECU setting of modern cars.
Even when you take your feet of the pedal in Santro or M800 the engine revs don't come down below a certain rpm. Added to that both M800 and Santro have good low end torque.

It's not an ECU setting.
Diesel cars are generally low revving engines and hence when you're not accelerating, the RPMs tend to drop faster.

Petrols are relatively higher revving, hence they drop RPMs slower.

also the construction of the engine comes into play.
Sprucegoose is offline   Reply With Quote
Old 25th March 2011, 16:07   #56
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,057 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by Daewood View Post
That must be due to the ECU setting of modern cars...
...Added to that both M800 and Santro have good low end torque.
Quote:
Originally Posted by Sprucegoose View Post
It's not an ECU setting.
Diesel cars are generally low revving engines ...
Petrols are relatively higher revving, ...
.. also the construction of the engine comes into play.

Its simply due to the higher compression ratio of diesel engines.
dhanushs is offline   Reply With Quote
Old 26th March 2011, 19:38   #57
BHPian
 
Join Date: Jun 2008
Location: Chennai
Posts: 39
Thanked: Once
Smile Re: What to do in case of Brake Fail !!

Good insights.

What should i do with the clutch? Should i step on it?

Is there a safety system in any car that brakes the engine on such failures?

Will ABS help in case if i pull the handbrake fully up?

Check this site - How to Stop a Car with No Brakes - wikiHow
hirajan is offline   Reply With Quote
Old 28th March 2011, 09:29   #58
Senior - BHPian
 
Join Date: Apr 2008
Location: Dombivli
Posts: 2,627
Thanked: 1,191 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by star_aqua View Post
NO it will not until the engine is being driven by the vehicle.
If you are advocating that we switch off the ignition and let the engine be running, driven by the wheels, I don't see how it makes a difference. The engine is still running, whether you switched off the ignition or not. And I don't know what's the difference between the two.

@hirajan, leave the clutch as it is, i.e. don't press it. Clutch should be depressed only when you are downshifting and then released immediately. If you keep the clutch depressed, it will allow the wheels to rotate free of the engine rotations, and you will lose any chances of slowing down the vehicle using engine braking.

Same goes for the handbrake and ABS. The handbrake works off a cable linked to the rear two wheels. It does not depend on the hydraulic braking system of a car. Since the ABS works off the hydraulic system, the handbrake is not part of the ABS equation. Meaning using the handbrake will never engage the ABS.

.

Last edited by honeybee : 28th March 2011 at 09:32.
honeybee is offline   Reply With Quote
Old 28th March 2011, 14:36   #59
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,057 Times
Default Re: What to do in case of Brake Fail !!

Quote:
Originally Posted by honeybee View Post
If you are advocating that we switch off the ignition and let the engine be running, driven by the wheels, I don't see how it makes a difference. The engine is still running, whether you switched off the ignition or not. And I don't know what's the difference between the two.
The reason has been mentioned before.

"A non-firing engine will create more engine braking than a firing one".
dhanushs is offline   Reply With Quote
Old 28th March 2011, 15:38   #60
Senior - BHPian
 
Join Date: Apr 2008
Location: Dombivli
Posts: 2,627
Thanked: 1,191 Times
Default Re: What to do in case of Brake Fail !!

Non-firing engine means you have to shift to either neutral or keep the clutch depressed. In both cases, the vehicle is free to roll down the road guided only by gravity, while you have no control over its speed whatsoever. I don't see what's the wisdom in that.
honeybee is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Temporary brake fail in Honda City gou Technical Stuff 33 13th August 2011 14:31
Brake fail causes riots in Khopoli nawabnabeel Street Experiences 20 9th June 2009 00:26


All times are GMT +5.5. The time now is 21:51.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks