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Old 13th October 2010, 22:28   #241
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Originally Posted by jigbarai View Post
More I think about it, Khanq's theory sounds a tad flawed.
Well, they are mere automatic transmission specialists for 2 decades. We should be able to trump them with a little google research.

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Originally Posted by jigbarai View Post
Let us go to a very very basic question here - What is the purpose of the N slot ? If you are supposed to be moving only between P and D - why do manufacturers even bother putting that N slot.
It is there for a reason. And to say that a particular slot causes more wear and tear - does not sound right.
Ok, I am an engineer, but from a branch other than automobile. Therefore, I am well aware that I won't be able to figure out a complex component like auto-transmission by logical deduction and Google research. I am only going by what I was taught when I first attended driving school in NJ in 1993 and what I have seen when others were driving AT ever since. I have never seen anybody shifting to N in a traffic light until now. That is why I was so puzzled by somebody doing it.

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Originally Posted by jigbarai View Post
All automatics can be started both in N and P slots. They are designed to do so. They wont start in any other slots.
I didn't even know it can be started in N. I thought N was only for towing.

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Originally Posted by jigbarai View Post
Its not just you Akshay - its a common experience. The car is less strained as well as the leg is more relaxed. Not just signals, even in traffic where the stop seems to be beyond 15-20 seconds, I move to N and relax.
How can you relax in N without any brakes? Hope you engage hand brake.

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Originally Posted by proton View Post
http://www.team-bhp.com/forum/techni...tomatic-7.html

Can't get more authoritative than that!
Than what? I don't see any automobile engineers in that link. BTW, that Torque converter lock up mentioned by sgiitk used to be there in my 2000 Acura 3.2TL.

Quote:
Originally Posted by proton View Post
I negelected to mention that I myself prefer to keep the engine running, BUT the shift in neutral and my eye on the rear view mirror. I also keep the vehicle positioned so that I can move it past and into an empty space by the front vehicle.

I don't want to sound paranoid and alarmist and cynical, but this is what happened. A friend stopped at an entry ramp and got hit by a truck from behind. This happened in LA, the truck driver was Mexican and without insurance. It was a mess, he had multiple fractures but survived.

Another friend was hit by a truck while waiting at the lights, on a scooter. He lost his life. This was here in Bangalore.

These are the reasons I keep the engine running and the box in neutral. I see a runaway truck in the mirror, I keep the option of getting out of the way open.
If you are in D, you can move out even faster.

Quote:
Originally Posted by proton View Post
Became quite well known helping Indian students learn driving: ate more curry in LA in a year than three years in UK courtesy grateful families. In US, without a car, you'll end up with feet like Donald Duck (quote from Cheech Marin, "Born in East LA" HaHa!). Great rescue for me from American food! Hairy experiences of numerous 16 wheeler artics bearing down on me and driving into gang ridden neigbourhoods though.
I can quote such stories from my 9 years in NJ too, but how is this relevant?
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Old 13th October 2010, 23:51   #242
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Hi Samurai Sir,

Just kidding about the v-16 quote! But not about his practical observations.

But seriously, if an engineer's words matter, I AM an automobile engineer and I can tell you that I've cracked open more Chilton, Haynes, Petersen and Works Manuals than I care to remember in my life, and I trust the gen from the blokes in the wrecking yards and tool hire shops of East London and HWY101 more than that in the manuals and docs, although I use both (read Zen and the Art of Motorcycle Maintenance!). I remember draining the oil in a tranny and then not being able to refill it because I followed a manual! It expected me to do it in a Authorised Workshop with specialised equipment. Moral of the story: walk through the sequence before you even chock the wheels.

Another thing, cooling in an autobox is very, very IMPORTANT. Keeping the shift in D in a prolonged stationary state is one of the factors, albeit minor, contributing to reduction in tranny life:

How often should the automatic transmission fluid... — Yahoo! Autos

The seals die, the box dies.

Since I've made it a habit to pick up Driving Licences (I stopped after my Gulf Licence) and since I show an interest in matters auto wherever I go, I soon get contacted by countrymen for my assistance (free! these are Indians!). I've driven 4wd/winch LR rigs in the Sahara, chased the Dakar rallyists in a Merc Unimog, drove a Beetle to Sweden from UK and got ticked off by co-passengers for tearing apart their guts (wheeee! no wonder the Swedes are tested for both ice and dry conditions!), drove back in a SL500 with studded tyres and got ticked off by cops for tearing apart their roads!

And the ride continues: 4/5 of my friends are in the market for an autobox, and while one has settled for the City, the rest of us are bracing for the Cruze blitz on our bank balances! Yours truly is the resource guy! Ah! Talk about pits! ICE, performance, bling, the list is endless.

Finally, autoboxes are quite simple: they started of as plain torque convertors, comprising a rotor and stator, with angled turbine blades. Think of the belt and v pulley of CVTs.

Then they slapped on a simple planetary gear arrangement. So you got a system that gave different ratios after convertor lockup. Then they slapped on a coupla more rings, giving the 3 speeder. Think of the Honda Cub (or Street) with its variable pulley, as well as its gearing. Same principle, only hydraulically controlled.

All very interesting!

Last edited by proton : 13th October 2010 at 23:59. Reason: added "free"
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Old 14th October 2010, 01:20   #243
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Originally Posted by proton View Post
In P mode the cooling mode (oil circulation pump) is stopped. It may be better to keep the cooling action working.
not all A/Ts have an oil cooler.

Secondly AFAIK, the ATF pump is directly connected to the input shaft which means, as long as the engine is running the pump is turning.

Quote:
Aw. Come on. How much more wear?
Minimal to nil. But just for argument's sake

But the latter theory is valid. When I'm in traffic, I release brake to crawl forward and hit brake to stop (all w/o touching the gas pedal). If that's too fast, then I drag the brake w/o relasing completely. Repeat 200 times till you reach home

Last edited by Mpower : 14th October 2010 at 02:34.
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Old 14th October 2010, 01:47   #244
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Originally Posted by Mpower View Post

As far as the brakes, yes wear is nil if there is zero relative motion between pad and rotor but usually there is some motion because most of us are not focused on keeping a firm foot n the pedal and tend to move an inch here and inch there.

But in general AT cars have more pad wear because we tend use to brake to control the car's progress (in D) when crawling in traffic rather than the gas pedal.
no sir, when I brake, I am still until ready to move again

in both AT and MT, you are off the gas pedal when braking. But in MT, you also disengage the engine with clutch, which is not possible in AT

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Originally Posted by blackasta View Post
I regularly switch off the engine in N (on traffic lights). Any disadvantages of that?
I have done that, forgotten to start the engine and had to listen to constant hoking because in the time I realized what was wrong (car rolled backwards instead of forward), and restarted the engine, signal was red again. I don't kill the engine anymore. if it's a long stop, I kill it but kep my fingers on the key to restart, and start it ahead of time.

Quote:
Originally Posted by Samurai View Post
e. I have never seen anybody shifting to N in a traffic light until now. That is why I was so puzzled by somebody doing it.

I didn't even know it can be started in N. I thought N was only for towing.
I almost always put it in neutral, but hand always on the lever (read the text above). And yes, you can star the car in neutral. I think the concept of neutral has been carried forward from MT gearboxes. But yes, you do need it for towing etc.
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Old 14th October 2010, 05:18   #245
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Default How do you drive through water?

I had a question that i have been pondering upon for some time now. May sound stupid, but the question is quite practical (especially in Bangalore)

Now when you reach a stretch that is covered with water and if the water level is higher than the exhaust on a manual i would have the clutch depressed (may be 75%) and drive through this ensures no water gets into exhaust. Now how would you maneuver an automatic through this?

Other than taking a different route is there a possibility of overcoming this puddle

Trust me especially in Bangalore it becomes essential to know as during monsoons most of our roads have more water than Ganga, Brahmaputra and Nile put together.
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Old 14th October 2010, 08:59   #246
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^^
for the love of your car - you never drive through water if it looks even a tad risky

if you are the Adventurous kind and there is a possibility - you go high throttle but more importantly with a steady throttle.
at no point should you have to pull your horses back or brake.
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Old 14th October 2010, 09:21   #247
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Originally Posted by Sutripta View Post
And slightly more if the engine is loaded more. Will be the first to agree that if the slight diff in FE is that important, what are you doing in an automatic!
With the fuel prices going thru the roof, FE will be an important factor - whichever car you talk about. The difference between manual and auto for any car is typically around 2 kmpl.
(Say 12 kmpl for a manual Santro and 10 for Automatic).

Now if you dont take care of things like the above (moving to N), using AC judiciously, driving the automatic sanely (without too much of kickdowns and constant braking) etc - that 10 kmpl may drop to 8 or even lesser.

Hence, you do as much as you can to have the convenience of auto but also optimize FE as much as possible.

Quote:
Just for the record, I apply the handbrake (rather than P) at long stops. Find it easier when moving off. I don't switch off because I like the AC to work all the time.
OT- I'm constantly amazed when I see so called 'luxury' cars driven with the windows rolled down. In the heat.
Most of us would keep the engine on for the AC.
But if it just the heat (and not noise/pollution) it is not uncommon to find people who feel comfortable with natural air.
Even i would roll my windows down at times if the air is fresh, and there is no pollution around.
It feels better than having to breathe in conditioned air all the time.
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Old 14th October 2010, 10:08   #248
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Originally Posted by proton View Post
Recent Australian Insurance Advisory quotes research showing that 3% fuel savings achieved just shifting to N at lights.
3% seems to be on the high side. Does it refer to the combined driving cycle, or is 3% the difference in idling fuel consumption between P and N?

Quote:
Originally Posted by proton View Post
Hi Samurai Sir,

Finally, autoboxes are quite simple: they started of as plain torque convertors, comprising a rotor and stator, with angled turbine blades. Think of the belt and v pulley of CVTs.

Then they slapped on a simple planetary gear arrangement. So you got a system that gave different ratios after convertor lockup. Then they slapped on a coupla more rings, giving the 3 speeder. Think of the Honda Cub (or Street) with its variable pulley, as well as its gearing. Same principle, only hydraulically controlled.
Did not know the Cub had a variator + a gearbox.

Regards
Sutripta
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Old 14th October 2010, 11:13   #249
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Quote:
Originally Posted by Sutripta View Post
3% seems to be on the high side. Does it refer to the combined driving cycle, or is 3% the difference in idling fuel consumption between P and N?


Did not know the Cub had a variator + a gearbox.

Regards
Sutripta

Dilip Bam called his Street the mini Bullet, I call mine the mini Hog! Sounds great and you can roll off in top gear!

My source does not specify where the 3% applies, but apparently it was significant enough to mention.

Quote:
Originally Posted by Mpower View Post
Secondly AFAIK, the ATF pump is directly connected to the input shaft which means, as long as the engine is running the pump is turning.
Good point, but I meant this:

Shifting To Neutral At Red Lights...Saves Gas?! - GasSavers.org - Helping You Save at the Pump Hypermiling and Fuel Efficiency Forum

Quote
Apparently some transmissions still run full pressure though the torque convertor while in neutral, and have the clutches disengaged while your foot is on the brake so savings are slight. Whereas when they are in park lubrication pressure is reduced and the pump is not working as hard. Full lube pressure at neutral is probably good for neutral coasting, but likely won't save you as much at stop lights as putting it in park would. However, if you've been slogging uphill recently at low city speeds and have been surfing the torque convertor, you might be better off leaving it in neutral as the higher lube pressure should give better cooling of the transmission through the tranny cooler.


As more and more owners go Auto, its important to get operation and maintenance right. Good thing this thread is in the most popular section: it would have got overlooked in the scary technical section.

Last edited by proton : 14th October 2010 at 11:15. Reason: Highlighted with italics
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Old 14th October 2010, 15:50   #250
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Yes Shifting to N as soon as we stop at signals, does save some fuel and increases FE. I was driving only in D before, now using N whenever i can has made my cars fuel efficient than before.
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Old 14th October 2010, 19:51   #251
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I should have been more specific - in India it is shift to N, engage handbrakes and kill engine (for the looong signals).
In US generally its shift to N and engage handbrakes. The signals here are quite ok.

One mechanic (US) once told me the reason for getting non functional taillamps (bulb type). You hit a signal, keep the brakes pressed for 30 sec to 1 min while the red taillamp glows. This heats up its leads which melts and short circuits, giving a defuct taillamp and (if bad luck hits) a police citation!
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Old 14th October 2010, 20:58   #252
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Default 'N' at traffic signal

Quote:
Originally Posted by proton View Post
Stopping at lights
Automatics

Slip onto neutral, engage handbrake and keep foot hard on the brake. If you wish switch off.

NEVER engage Park at the lights! More often than not one uses the box in the D or N and believe me buddy if you are not paying attention and have shifted to the P on a light, its really very possible that one shifts to R and thinks its a D and goes crashing into the rear. Its happened to many of us.

Keeping in D results in fuel wastage AND shooting forward in case of being rear ended.
In my car, when stationary with the AT in D, there is a slight vibration felt inside the cabin. When slipped into N, the RPM rises a wee bit and the car is perfectly calm.

It is mostly plains here in the middle east, hence even if you take your leg off the brakes, the car wont move from stop even in N.

Fuel wastage with D when stationary, might be true, but not bothered about it, as the fuel cost here is negligible. Wear & tear due to shifting between N & D - no idea.

Only concern is about taking leg off the brake while not paying attention. Actually, I got rear-ended once, just a 'kiss', the driver's explanation was that he was talking with his friend, was distracted, and took the foot off the brake.

If I am among the first couple of cars at the signal, I keep in N with the brake pedal depressed, so that I am ready to shift into D and move.

If I am further back, I engage the hand brakes and let go off the brake pedal, as I will get enough time to depress the brake pedal, shift to D and disengage the hand brake. This has been my habit since I started using AT's.

Or you could actually shift to P and engage the hand brake. (I have read somewhere that even when in P, it is best to engage the handbrake so as to avoid damage to transmission. ) But, it takes a bit more time to shift from P to D thru R & N. In my car, to shift out of P, you have to press the gear button on the gear level, and the brake pedal has to be depressed. Also, if not paying attention, you could end up backing up into the car behind as mentioned by proton.

So its kind of 'easy' & 'comfortable' to keep the car in N, rather than shifting to P.
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Old 14th October 2010, 21:08   #253
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Another BIG reason to change from D to N...is the virbation. In many cars (mine esp), I can feel steering and gear shaking and vibrating when stopped in D whereas N is super smooth idle.

In some old cars, the lever lock button thingy wears out and so you can just nudge the lever to N.
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Old 14th October 2010, 21:10   #254
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Originally Posted by Mpower View Post

In some old cars, the lever lock button thingy wears out and so you can just nudge the lever to N.
Its like that in some new cars too. Like in my Accord from D to N or N to D you dont need to press the button on the gear knob or the brake. Just move the lever.
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Old 14th October 2010, 21:35   #255
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Originally Posted by azeemhafiz View Post
I had a question that i have been pondering upon for some time now. May sound stupid, but the question is quite practical (especially in Bangalore)

Now when you reach a stretch that is covered with water and if the water level is higher than the exhaust on a manual i would have the clutch depressed (may be 75%) and drive through this ensures no water gets into exhaust. Now how would you maneuver an automatic through this?

Other than taking a different route is there a possibility of overcoming this puddle

Trust me especially in Bangalore it becomes essential to know as during monsoons most of our roads have more water than Ganga, Brahmaputra and Nile put together.
Towards the end of 2007, there was a heavy rain in Dubai & most of the roads were flooded. I drove through that for more than an hour to reach office and again another 3 hours to reach back home. At some places, the water level was higher than the bottom of the doors.

My Tiida didnt leave me stranded, didnt even cough or sneeze. All along I was driving with AT in D.
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