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


Reply
 
Thread Tools Search this Thread
Old 7th July 2010, 19:10   #46
BHPian
 
A350XWB's Avatar
 
Join Date: Oct 2009
Location: BLR/FRA/STR
Posts: 791
Thanked: 528 Times
Default

^^ It does not have anything to do with the hydraulic system. This behaviour is due to the vacuum booster and is normal. More reading here : HowStuffWorks "How Power Brakes Work"
A350XWB is offline   Reply With Quote
Old 7th July 2010, 19:23   #47
Distinguished - BHPian
 
paragsachania's Avatar
 
Join Date: Nov 2007
Location: Belur/Bangalore
Posts: 4,261
Thanked: 10,561 Times
Default

Quote:
Originally Posted by A350XWB View Post
^^ It does not have anything to do with the hydraulic system. This behaviour is due to the vacuum booster and is normal. More reading here : HowStuffWorks "How Power Brakes Work"
Err, my bad. I indeed meant vacuum system since all the brakes today are 'vacuum asisted'. Somehow the word went off my mind. :-)
paragsachania is offline   Reply With Quote
Old 7th July 2010, 19:36   #48
BHPian
 
Join Date: Aug 2008
Location: mumbai
Posts: 176
Thanked: 11 Times
Default

Quote:
Originally Posted by iraghava View Post
And so is driving in Neutral because you're again going to over-strain the brakes if you do it excessively and that can again lead to a brake failure.

Driving in neutral or putting the engine off during downhill trip is a strict no no. Not because of strains to engine or otherwise.

Coming downhill be in the same gear as you would go up. If you were in second gear while climbing be in the same gear. There is a certain amount of engine brake which gets applied.

Do not think about fuel savings!! your life and accident free driving is more important than saving a few bucks. You would save a litre or two of petrol say Rs110 or so.

This is not a safe way of driving.
gururaj r is offline   Reply With Quote
Old 7th July 2010, 19:39   #49
BHPian
 
Join Date: Oct 2009
Location: Mumbai
Posts: 170
Thanked: 12 Times
Default

or put in another way
Fuel saved - 4 litres - Rs. 200
Brake Pad replacement - Rs. 768 + labour (Figures as per the MGA prices posted on the forum at
Quote:
Originally Posted by naveen.raju View Post
Here's the Latest list for all the cars:
)

That and the obvious risks to life and limb

Last edited by adits : 7th July 2010 at 19:43. Reason: Added MGA price list link
adits is offline   Reply With Quote
Old 7th July 2010, 21:19   #50
Senior - BHPian
 
anilisanil's Avatar
 
Join Date: Jun 2010
Location: Pune
Posts: 1,435
Thanked: 288 Times
Default

Post deleted by the Team-BHP Support : One-liners that add ZERO value to the thread are strictly prohibited on Team-BHP. In fact, they are considered as SPAM. Please do not hit the post submit button unless you have something of value to add to the thread.

We advise you to visit our board rules before proceeding any further.

Last edited by GTO : 8th July 2010 at 20:01.
anilisanil is offline   Reply With Quote Received Infraction
Old 29th July 2010, 15:11   #51
BHPian
 
dmaheshkumar's Avatar
 
Join Date: Aug 2008
Location: Coimbatore
Posts: 134
Thanked: 18 Times
Default very dangerous

Even in two wheelers this is not adicable.
See now a days the brakes are working with boosters which will take the vaccum from the alternator.If the engine is switched off the alternator will not work.

So the vaccumm will not be generated and the brakes will not be perfectly stop your wheels rolling.Old model cars will have the brakes connected with the oil directly going to the mass cylinder and it has been replaced with this booster tech.

So dont try to do this.
dmaheshkumar is offline   Reply With Quote
Old 29th July 2010, 15:15   #52
Senior - BHPian
 
vasoo's Avatar
 
Join Date: Jul 2007
Location: Memphis TN
Posts: 1,031
Thanked: 207 Times
Default

May be possible to do in older models which does not have lot of "power assisted" thinges. Nowadays, most cars come with "drive by wire" or power steering, brake, mechanism, it is strictly not advisable to switch off the the engine while coasting or going down hill. In my car, the steering becomes a piece of rock, the moment engine is switched off. Even the brake feels very vague...
vasoo is offline   Reply With Quote
Old 30th July 2010, 00:02   #53
Senior - BHPian
 
Join Date: Sep 2006
Location: zxc
Posts: 3,394
Thanked: 658 Times
Default

Quote:
Originally Posted by dmaheshkumar View Post
Even in two wheelers this is not adicable.
See now a days the brakes are working with boosters which will take the vaccum from the alternator.If the engine is switched off the alternator will not work.
Little correction for the sake of quality.

Assisted brakes does not work off alternator. But from vacuum created by engine.

Even if ACC is on and engine is not fired up. Alternator will charge your battery while rolling downhill. Not fully but it will.

Now for the main topic. No its not a good idea to drive with engine turned off. Not even advisable to roll the car in neutral even if the engine is on.
For this you will have to control your car though brakes only. Results may be catastrophic. Brakes may heat up pretty soon and may encounter lock up, which we all know is a dangerous scenario.
SirAlec is offline   Reply With Quote
Old 30th July 2010, 00:41   #54
Senior - BHPian
 
ph03n!x's Avatar
 
Join Date: Jun 2008
Location: Madras
Posts: 1,705
Thanked: 118 Times
Default

I know enough has been said on a 3 year old thread over four pages, but I have to say this - this is the DUMBEST thing to do in motor vehicle!! Having the engine switched off will climbing down a hill is as good as jumping off a suicide point stark naked singing "I believe I can fly..." - whoever wants to do this to save fuel, please buy a bicycle instead (and try not to ride straight on a hairpin).
ph03n!x is offline   Reply With Quote
Old 30th July 2010, 11:58   #55
Distinguished - BHPian
 
sgiitk's Avatar
 
Join Date: Dec 2007
Location: Kanpur
Posts: 7,162
Thanked: 3,757 Times
Default

In one word BAAAAD. Modern cars have many other systems relying on the engine - brakes, steering, etc. so the practice is bad. Also,, when descending slopes you should be in gear (the correct gear for going down is the same as the one for going up). I cannot imagine any condition where the engine can be safely switched off!
sgiitk is offline   Reply With Quote
Old 30th July 2010, 21:41   #56
BHPian
 
Join Date: Jun 2010
Location: chandigarh
Posts: 277
Thanked: 16 Times
Default

Its clear from the posts that everyone believes it is unacceptable (even downright stupid) to drive downhill or on plains with engine off.

But we still have a lot of different views on rolling in neutral with Engine ON on plains .
Can we just discuss this in another thread with specifically this title (or change title of this one). So everyone with a view on this puts forward their points and we can reach the correct verdict on this ?
guptavis is offline   Reply With Quote
Old 30th July 2010, 21:44   #57
BHPian
 
rajushank84's Avatar
 
Join Date: Nov 2009
Location: California, USA
Posts: 861
Thanked: 350 Times
Default

In one word: Bad. In two words: Very bad.
rajushank84 is offline   Reply With Quote
Old 30th July 2010, 22:02   #58
Senior - BHPian
 
aaggoswami's Avatar
 
Join Date: May 2007
Location: Vadodara
Posts: 4,675
Thanked: 1,427 Times
Default

Never try that. Never.
I would like to explain with one incidence of mine. I did this even after repeatedly reading about cars and how many systems are dependent of engine alone.

While coming back alone after dropping my mom in our native village I managed to spot one railway crossing closed. We cross the same railway line thrice. Most probably if you encounter one crossing closed, you will have the other closed too by the time you reach the crossing.

I had a brief 140 kmph stint, so in order to save fuel ( the economic biker in me woke up suddenly after high speed stint on a single lane highway ) I first shifted into neutral, then more economic sense entered my brain as a result of which I switched off engine. The problem was not visible when the road was straight. But after that there is mild turn towards right and I realized the steering was heavy, normally what I would do with ease ( very easily ) was now tough to handle even with both the hands. The brakes, well after a couple of slight application ( might be 3 times ) the braking was weird but applicable. Thankfully speed was quite low ( due to all that rolling ) and I switched on the engine.

This happened in relatively less traffic infested and good smooth roads of Gujarat. Just imagine what would have happened if the car was going downhill and I switched off the engine.

Its nice to save on fuel by not speeding ( if one is so interested in saving fuel ), but its non sense to save fuel by switching off engine when the car is moving. If at all one wants to save, drive at lower speeds, but never ever switch off the engine when the car is moving/rolling.
aaggoswami is offline   Reply With Quote
Old 30th July 2010, 23:07   #59
Distinguished - BHPian
 
sgiitk's Avatar
 
Join Date: Dec 2007
Location: Kanpur
Posts: 7,162
Thanked: 3,757 Times
Default

Quote:
Originally Posted by guptavis View Post
But we still have a lot of different views on rolling in neutral with Engine ON on plains .
It is equally stupid. The car has to be in gear all the time it is moving. Try it in the UK driving test and you will FAIL. As simple as that.
sgiitk is offline   Reply With Quote
Old 5th August 2010, 13:47   #60
BHPian
 
adrian's Avatar
 
Join Date: Sep 2009
Location: Trivandrum
Posts: 752
Thanked: 587 Times
Default

Hi friends, I want to share an incident that happended in our state. A group of young men took a rented Toyota Qualis to the hill station and on their down hill journey switched off the engine. The driver did one more thing to get him closer to heaven. He removed the key from the ignition column. The vehicle with engine assisted brakes failed to stop at a hair pin and on the first rotation of the wheel to clear the curve, the steering wheel locked with the wise squad ending up in heaven.

Moral : Stick to the basics of driving ! Do not improvise !!!
adrian 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
Oberoi Motors, Tata-Fiat dealership, Noida: Good experience turned sour sidindica Indian Car Dealerships 17 19th July 2011 15:33
5009 KMS-A'bad-Calicut-Bangy-Hyd-Aur'Bad-A'Bad-Report ramkya1 Travelogues 48 4th August 2010 00:04
A bad bad bad night for me.... Ranjan Sharma Street Experiences 38 8th April 2010 12:02
My Unicorn turned OFF instantly while riding Bhargava_sr Motorbikes 14 4th September 2009 17:36
My accident - Bad brakes, bad rain, bad luck... vezj420 Street Experiences 41 22nd May 2007 10:49


All times are GMT +5.5. The time now is 08:39.

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