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Old 16th October 2012, 14:02   #271
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Default Re: Automatic Transmission v/s Manual

@tj123; It is always advisable when descending to switch the transmission to a setting where engine braking is available. Take it from a lucky guy who survived in the French Alps, not aware of the etiquette of driving an AT.
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Old 16th October 2012, 16:31   #272
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Default Re: Automatic Transmission v/s Manual

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Originally Posted by ananth_iy View Post
I am not sure which AT you saw holding onto RPM while going downhill. If the AT has a hill control or ascent and descent control (like the Scorpio does), it does indeed hold onto RPM, on the downhill in D. Brakes are not needed. The AT in an i10 would probably need brakes to be applied in the downhill, like my Santro AT does. However, I have found, even the Scorpio tends to go into a "freefall" in D if the slope is way too steep. That when you will need the S or M.

Thanks. The AT is Civic which donot have assists. The slope was not sleep though, but i could see the RPM holding and not increasing and the gear was in the one that I had slotted it before allowing it to go free. (Gear position was noted using the paddle shifts, just before and after this)
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Old 16th October 2012, 17:34   #273
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Default Re: Automatic Transmission v/s Manual

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Originally Posted by Diesel lover View Post
Is it possible to shift from normal 'D' mode to 'D with OD off' / '2' / 'L' or vice versa on the fly? Or we need to bring the car to a stop and then do the changes and drive on? Ideally such instructions must be there in the car manual but sadly there isn't any.

From D to 2 or from D to L or from 2 to L, it is required to press the lock switch but it isn't required when moving from L to 2 to D.
Yes you can shift from 'D' mode to 'D with OD off' while driving. This should ideally should not slow you down but only increase the rpm a bit when OD is off.

BUT be very careful while changing from 'D' to lower gears like 2 or L. It can be changed while moving but at very low speed.
I would go ahead and say it should not be done while moving at all. It would be like changing to second or first gear in manual box while moving. If you are at higher speed and engage these gears the result could be disastrous.

Mostly you will not be required to engage to these gears in normal conditions. It is only used when you need to keep the car in that gear and not shift up, like going downhill or trying pull the car out of a ditch when it is stuck

Last edited by sandeep_s : 16th October 2012 at 17:46.
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Old 17th October 2012, 14:51   #274
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Default Re: Automatic Transmission v/s Manual

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Originally Posted by sarathlal View Post
Thanks. The AT is Civic which donot have assists. The slope was not sleep though, but i could see the RPM holding and not increasing and the gear was in the one that I had slotted it before allowing it to go free. (Gear position was noted using the paddle shifts, just before and after this)
The latest Honda Civic AT has "Grade Logic Control" which would be same as Hill control / ascent and descent control. Each manufacturer calls the same technology by a different name.
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Old 17th October 2012, 16:40   #275
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Default Re: Automatic Transmission v/s Manual

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Originally Posted by ananth_iy View Post
The latest Honda Civic AT has "Grade Logic Control" which would be same as Hill control / ascent and descent control. Each manufacturer calls the same technology by a different name.

Ha, there you go. So this is the reason why this guy keeps shifting down when I go on an ascent. Has on number times joked on how the civic is able to understand the terrain!
What am putting in is based on the experience alone, so let me check on whether the Civic actually employs it. Don't know whether these things are already known to others, but is news to me

EDIT: Yes, as ananth_iy has said, the Civic do have the Grade Logic Control as specified in their original site; http://www.hondacarindia.com/Civic/Specifications.html

So, some myths on the wear and tear of brakes, OD, engine braking etc for the Civic is cleared.

Last edited by sarathlal : 17th October 2012 at 16:52.
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Old 17th October 2012, 18:30   #276
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Default Re: Automatic Transmission v/s Manual

Question regarding Honda's grade logic

Is it based on the correlation to Engine RPM and the actual wheel speed for a given throttle input?
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Old 18th October 2012, 11:33   #277
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Default Re: Automatic Transmission v/s Manual

It also is based on the engine load it senses, e.g. when ascending there is more load on the engine so it holds on to a lower gear. Similarly when descending. If you drive it sedately, the gear changes are noticeable at certain fixed speeds, e.g. 40 km/h, 55 km/h, etc.
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Old 18th October 2012, 11:45   #278
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Default Re: Automatic Transmission v/s Manual

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Originally Posted by sgiitk View Post
@tj123; It is always advisable when descending to switch the transmission to a setting where engine braking is available.
which means in cars like the old Corolla I had earlier , locking the lever in the 2 position while descending would be the way to go.
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Old 18th October 2012, 11:56   #279
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Originally Posted by vigsom View Post
which means in cars like the old Corolla I had earlier , locking the lever in the 2 position while descending would be the way to go.
Yes, but each transmission has its own set of settings. Important that you get engine braking. The Tacho will guide you a lot here.
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Old 18th October 2012, 13:08   #280
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Default Re: Automatic Transmission v/s Manual

Quote:
Originally Posted by vigsom View Post
which means in cars like the old Corolla I had earlier , locking the lever in the 2 position while descending would be the way to go.
Quote:
Originally Posted by sgiitk View Post
Yes, but each transmission has its own set of settings. Important that you get engine braking. The Tacho will guide you a lot here.

Well not a hard and fast rule here i guess, and most importantly depend for vehicle types.
Assuming we know the 'gear holding' modes of the transmission in our vehicle, the best way to judge is by getting the feedback from the vehicle itself.
For eg, if in the set mode, we are able to feel the vehicle holding onto the RPM without having to brake to do so, the engine is assisting the braking and we are good. But if the hold doesn't happen, try to activate the assist (in case of Honda's grade logic, reduction in the speed by slight braking thereby making the gear shift a step or two lower and then leaving the throttle) or if such a feature is not available, then slot to the next mode and see.
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Old 18th October 2012, 21:04   #281
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Default Re: Automatic Transmission v/s Manual

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Originally Posted by sandeep_s View Post
BUT be very careful while changing from 'D' to lower gears like 2 or L. It can be changed while moving but at very low speed.
I would go ahead and say it should not be done while moving at all. It would be like changing to second or first gear in manual box while moving. If you are at higher speed and engage these gears the result could be disastrous.
Hi,
Could you pls. explain, esp the part marked out in bold.

Regards
Sutripta
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Old 19th October 2012, 09:54   #282
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Default Re: Automatic Transmission v/s Manual

I think the AT has enough brains to decide when to downshift to the selected range, so if the speed is too high it will wait for you to come down before executing the downshift. Even my old Zen (1997 vintage) had this!
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Old 19th October 2012, 10:18   #283
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Default Re: Automatic Transmission v/s Manual

Quote:
Originally Posted by Sutripta View Post
Hi,
Could you pls. explain, esp the part marked out in bold.

Regards
Sutripta
In the Auto box, if you leave the gear lever to 2, that means you limiting the gear box to second gear. This is usually used for the driving condition where it requires more torque than speed.
When people are going downhill or driving in snow they change it to 2 not D. So that we get enough engine braking and also sufficient torque on demand.
On the move we usually do not change to lower gears. It is done before starting off or you should be sufficiently slow to change to one of the lower gears. Assume If you are at 30 km/hr and change it to 2 then the rpm will shoot up to match the speed. So you can guess what happens if you do change at higher speeds…

It did happen to me once, when I was teaching driving to one of my friends back in US, in Accord V6. He for some reason moved the gear lever to 2 while at 30 mph. Oh… my heart was in my mouth for a minute. But nothing happened as the speed was very low. Never let him to drive my car again.
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Old 19th October 2012, 12:52   #284
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Default Re: Automatic Transmission v/s Manual

Quote:
Originally Posted by sandeep_s View Post
In the Auto box, if you leave the gear lever to 2, that means you limiting the gear box to second gear. This is usually used for the driving condition where it requires more torque than speed.
When people are going downhill or driving in snow they change it to 2 not D. So that we get enough engine braking and also sufficient torque on demand.
On the move we usually do not change to lower gears. It is done before starting off or you should be sufficiently slow to change to one of the lower gears. Assume If you are at 30 km/hr and change it to 2 then the rpm will shoot up to match the speed. So you can guess what happens if you do change at higher speeds…
The engine speed does rise up but for a brief moment and after that the engine slows down and its braking slows the vehicle. Have owned and driven two generations of Accord in the US and have had no problem with shifting down to 3 and then sometimes to 2 from 'D'. Of course, I have done it at appropriate speeds. However, I learnt this technique in a Merc and it being a bigger engined and rear wheel driven vehicle, seemed more suited to this.
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Old 19th October 2012, 19:18   #285
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Default Re: Automatic Transmission v/s Manual

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Originally Posted by venkatrx View Post
* In US 'automatic transmission' is the default, where as in india it is 'manual transmission', car-gurus, whats the major reason for this difference?

* BTW people keep saying automatic transmisstion has lot of problems, is that really true?

* apart from santro-automatic, honda-cvt are there others cars which provide the 'automatic' option? in the sub-10 lakhs category.
Very long thread already!
Let me give you my perspective; As you say in the USA AT is the norm. very few manual transmission around.

There are probably various reasons. My gut feeling is as follows; From the 50-60's onward, American cars have always been bigger and more HP than Europeans. In those days European cars, by and large, had far smaller engine and therefor HP. Also in those days the AT were very inefficient. Meaning you had a lot of power loss. So if you didn't have to much power to begin with, you lost a big percentage if you went for an AT. Fuel efficiency has always been a more prominent factor in Europe than in the USA. Americans are just very lazy drivers. Driving an automatic comes very natural to them. Why would you have a manual.

Now, a lot has been said how manual is more sporty than auto. However, in all honesty that is a lot of rubbish and just very much "macho talk". Fact is that most of us couldn't outperform a good automatic transmission these days. Unless you're an exceptional driver, like say for instance race or rally driver.

The high HP (horse Power) has also another practical consideration; See the above. My Jaguar XJR has nearly 400BHP and it drives beautifully with its automatic. Trying to tame that sort of horse power manually takes a very skilled right food indeed!

Now, I noticed a lot of post about how the various drive options come into play. E.g. downshifting from D to 2 on a downhill stretch. Absolutely correct. However, I have never ever come across any American that would even remotely understand this. They keep their AT in Park or in Drive. The difference being their foot on the brake. No matter how many different options there would be available.

I spend considerable time in Colorado driving in the Rockies and I can tell you that every American cars coasts downhill with their foot firmly planted on the brake! Americans have never heard this idea that you need to put your box in neutral whilst waiting at a red light. So they don't. Again, just foot on the brake. Just look at all those red brake lights you see in the movies!

Me being an engineer, of course I use every technical option that is available to me. So I always used to shift down to 3 or 2. Even just coming of our driveway.

Just one more of my own experiences with auto versus manual. My wife grew up in the Barbados, West Indies. About 80% of the cars are auto out there, mostly Japanese/Korean jobs. And some real rich gits drive Mercedes/BMWs.

Anyway, Barbados gets some monumental rain. Meaning roads flood completely. It was a well known fact that no matter what car you owned, you would never ever attempt to drive one across a flooded road unless you were driving a manual!

All autoT's would stall halfway. Never really understood it, but I figure its' probably related to most modern Auto's having a fair amount of electrics and electronics involved and they don't do well in water!

I own cars with manual as well as auto transmission. I love driving my Alfa Romeo Spider on little twisty roads, manual shifting all the time. It's a great experience. But I used to drive upward of 50.000 miles per year on business and that is so much more easy with an auto box!

I've owned several Volkswagen Passat and Audi's with the DSG box! Amazing!
Don't think you can out shift these cars with your little manualT, because you can't, unless you're Stirling Moss.

Now here's something for the anorak brigade: When I put my Jaguar XJR in D, it will actually pull away in 2nd gear. It's got so much torque, you would not believe. Only when I put it into S (Sport) it will it pull away in 1st! It will also firm up the suspension, change the gear change pattern and phone my wife I'll be home early. Furthermore, this auto-box also has 2 gears going reverse!! How cool is that???

I've never had any problems with my manual or my auto transmission for that matter. Other than normal maintenance and wear and tear. For the enthusiatic DIY mechanic; I'd happily take most manual boxes apart, but I would never ever attempt an auto box. Once I take it off, it would go straight away to a specialized shop.

To sum it up. I don't think that there are any material differences in reliability these days between auto or manual boxes. On older cars there definitely are.

Efficiency between auto and manual is marginal. So, yes on paper the manual version will be a little bit faster, but in practice most of us won't be able to prove that. Same goes for fuel efficiency.

So, it really comes down to personal preference. I will take an automatic for my daily drive and a manual for my fun/hobby drives, thank you very much.

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