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Old 19th March 2009, 13:56   #61
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Originally Posted by rishia View Post
was wondering if using the lower gear (which definately slows down the car because of engine braking) could be used instead of brakes to slow down. Will that affect the transmission / FE in any way?
Never shift the auto transmission stick when the car is on the move in order to achieve engine braking. All stick movements must be made when the car is stationary, unless the car comes with a 'shift of the fly' design. 1 and 2 are meant to achieve engine braking downhill and to avoid hunting when going uphill at a certain low and nearly constant speed.

OD - This switch must remain in the 'On' position if you want the transmission to move up to the overdrive on its own, and this is necessary for fuel economy and to prevent overrevving the engine. Again, there is no reason why you must switch it off unless you are going uphill at a speed where the trans shifts from 3rd gear to OD, and you want to prevent it from constant shifting up and down. All cars indicate 'OD off' in the driver information area if you switch this off.
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Old 19th March 2009, 14:19   #62
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Originally Posted by Rajesh Rawal View Post
another quick question since you drive an A/T santro ,the OD (Over drive) thing ,when should that be used ,i have never used the same so far .how does it help driving with the OD mode on?
I leave OD on all the time. I think it was originally a 3-speed box. When they added a fourth gear instead of changing the entire shifter they just added a button for the purpose. Also, except for P (and to a limited extent R) you can shift while moving since the actuation is electronic and not mechanical. In the old days with mechanical shifters it was almost obligatory to do all your shifting when stationary.
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Old 19th March 2009, 14:29   #63
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Some good info, thanks!
My initial question is still not very clear to me. Let me try and rephrase it. Say I'm going on a flat road at a good speed, but 200 m down the road I see I have to stop. I have 2 options,
Option 1 - Release the gas pedal and then apply brakes when I need to stop and then put the gear in N.
Option 2 - Release the gas pedal, and when I go in a little further, apply the lower gear which will slow down the car because of engine braking and then apply the brakes when it's required (effectively applying brakes at a lower speed than option 1) and then move to N when I'm stopped.

Definitely, Option 1 is harsh on the brakes for obvious reason, but I needed to know if Option 2 is harsh on anything else, Transmission / FE ?

@Rajesh Rawal the OD button can be kept on all the time, it isn't effective unless you're crusing smoothly at a certain speed (from what I know it's just a higher gear) so if you're at lower speeds it doesn't matter if it's on or not. That way it will kick in whenever it can.

Regards,
Rishi
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Old 19th March 2009, 14:42   #64
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Rishi,

This is what I have tried to reply in my post. In an electronically control auto trans box, if you shift to say 1, when you are doing 60 kmph, the trans will not shift to 1 since it is a protective mechanism. The trans will engage 1 only when the car has slowed down to 1's upper range. This is explained in the Santro AT's manual, for example.

Having said this, this protective mechanism must not be exploited, and all selections on the stick must be made when the car is stationary to minimize damage to your trans.

Trust this information helps.
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Old 19th March 2009, 15:09   #65
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Quote:
Originally Posted by sgiitk View Post
I leave OD on all the time. I think it was originally a 3-speed box. When they added a fourth gear instead of changing the entire shifter they just added a button for the purpose. Also, except for P (and to a limited extent R) you can shift while moving since the actuation is electronic and not mechanical. In the old days with mechanical shifters it was almost obligatory to do all your shifting when stationary.

I don't think you should do that... O/D is certainly not a fourth gear.. as a matter of fact it acts as one lower gear than you are engaged in... it is to be used for overtaking / getting a surge of acceleration...

For a manual.. it would be that if you are cruising in 5th gear and need to overtake a truck fast, you go to the 4th gear... O/D is for that purpose.

Using it for all times may put pressure on the engine / reduce FE

P.S: the same is as explained in my Corolla a/t manual.
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Old 19th March 2009, 15:31   #66
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@rishia: You just release the gas pedal and then brake as required. I do not support the American habit of using both feet on AT cars. I just use my left foot. One should always drive smoothly. This applies to braking as well.

With ATs you expect the brakes to last shorter than with MTs. In Europe many cars with ATs come with upgraded brake systems for this very reason.
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Old 19th March 2009, 17:57   #67
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Quote:
Originally Posted by sdmn View Post
Never shift the auto transmission stick when the car is on the move in order to achieve engine braking. All stick movements must be made when the car is stationary
If that is true of your car, then that is some pretty weird gear box you have there!

This is absolutely not true of driving with automatic transmission. You can use the lever to force a downshift either for acceleration or braking any time you like. The automatic box itself should indeed, prevent a shift into a gear that is too low for the car's current speed.

Also, (in my experience) the button on the lever prevents shifting to P or R without extra thought, as doing this with the car moving will shred the inside of your gear box.

AT --- gearbox without a clutch: change up or down whenever you need. Really. This is one of the things that is so great about them.

Last edited by Thad E Ginathom : 19th March 2009 at 17:59.
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Old 21st March 2009, 16:46   #68
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IMO, the 2 thing is still not clear.

(1) Weather we should put P / N / D+brakes during signals?

(2) Weather we should use only right feet or both while driving AT?

Gurus please comment.
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Old 21st March 2009, 16:59   #69
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Quote:
Originally Posted by loving_alaap View Post
IMO, the 2 thing is still not clear.

(1) Weather we should put P / N / D+brakes during signals?

(2) Weather we should use only right feet or both while driving AT?

Gurus please comment.
1) 'D'+ brakes is for the impatient folks.'N' if your pulling up the handbrake or pressing the brake pedal.'P' is the safest.no need to use the brakes and the car wont roll.

on a long signal i usually used to shift to P and D just a few seconds before the signal starts.

2) ONLY right foot for sure.


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Old 21st March 2009, 18:16   #70
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If your car has a DSG gearbox, you must go to neutral when the car is stopped or risk frying the gearbox.
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Old 21st March 2009, 18:31   #71
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Quote:
Originally Posted by revtech View Post
1) 'D'+ brakes is for the impatient folks.'N' if your pulling up the handbrake or pressing the brake pedal.'P' is the safest.no need to use the brakes and the car wont roll.
Car may move in neutral if you are stopping on a slope. I normally put it to N and apply the parking brake if the red signal is going to be long.
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Old 22nd March 2009, 14:11   #72
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Originally Posted by ImmortalZ View Post
If your car has a DSG gearbox, you must go to neutral when the car is stopped or risk frying the gearbox.
Hi,
Would you please elaborate on this a little??
you are saying that repeated use of the *D* mode with brakes will fry the gearbox during long stops ?
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Old 22nd March 2009, 14:37   #73
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Guys at a signal it's quite simple really:

If the signal is less than a minute [60 seconds] then keep the car in D and hold the brakes.

If the signal is longer [ex 100 seconds] then shift the car to N or P. In N you need to either hold the brakes or engage the hand brake. If in P, the car will not move anyway, so it isn't necessary to engage a brake, but I suggest you pull the hand brake anyway.

Shifting from D to P or N at short signals will increase the wear of the gearbox.

The O/D myth: Ok well in ATs, gears will change at low rpms this is to make driving smoother and help FE. When you stomp on the gas however your car will rev past it's normal shifting limit. With the OD engaged, your car will hold gears for longer and that will provide you with more power at higher rpms. However the downside is that it kills FE. NOTE: In some cars the OD is reverse ex: Corolla when you push the button and it says OD off on the display, that's when it's engaged. You can tell the difference when you accellerate, gears will be held for longer, and there is a difference in brake feedback.

ATs do have clutches, but they are known as wet clutches. These generally last the life of the car, however if you illtreat your AT and have to get your tranny overhauled, then your in for a huge bill.

Shifting on the fly: Refrain from this habbit. Brakes on all ATs are more powerful that those of their MT counterparts. In standard ATs please don't shift to D1 or D2 from D for increase engine braking. Normally ATs will not allow you to shift from D to P or R on the move, but I have come accross some which do [GV, i10]. [You may however play with this if you have a tiptronic or paddle shift mechanism.

How many feet: In an MT you normally use your right leg for the brakes and accellerator, and the left for the clutch. Now why is it so hard to realise that it's the same with an AT? Right leg for both pedals [Or left, but choose only 1].

Hope I could be of some help,
Doc
[NOTE: I own 2 AT corollas in India, an AT Gallant and drive my uncle's cars, all 7 AT in the states, so been driving autos for some time now]

Last edited by DocG : 22nd March 2009 at 14:51.
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Old 22nd March 2009, 15:17   #74
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Quote:
Originally Posted by sgiitk View Post
... Also, except for P (and to a limited extent R) you can shift while moving since the actuation is electronic and not mechanical. In the old days with mechanical shifters it was almost obligatory to do all your shifting when stationary.
Would not recommend movement to 'P' or 'R' when moving, definitely not to 'R' when in forward motion.

Quote:
Originally Posted by rishia View Post
...
Option 1 - Release the gas pedal and then apply brakes when I need to stop and then put the gear in N.
Option 2 - Release the gas pedal, and when I go in a little further, apply the lower gear which will slow down the car because of engine braking and then apply the brakes when it's required (effectively applying brakes at a lower speed than option 1) and then move to N when I'm stopped.
...
@Rajesh Rawal the OD button can be kept on all the time, it isn't effective unless you're crusing smoothly at a certain speed (from what I know it's just a higher gear) so if you're at lower speeds it doesn't matter if it's on or not. That way it will kick in whenever it can...
Go for option 1. Do not be penny wise pound foolish.

Use the OD when you want more rev in the gears.

Quote:
Originally Posted by loving_alaap View Post
...

(1) Weather we should put P / N / D+brakes during signals?

(2) Weather we should use only right feet or both while driving AT?
...
1. Putting P/N/D+ brakes depends on the time and the slope that you are in. If you have enough time and want to negate one chance of accident, use P. Know incidents where people move to D+brake and concentration moves to something else and they release the pressure on the brake and BHAM! hit the one in the front!

2. ALWAYS use only the right feet.
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Old 22nd March 2009, 16:08   #75
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Quote:
Originally Posted by babhishek View Post
Hi,
Would you please elaborate on this a little??
you are saying that repeated use of the *D* mode with brakes will fry the gearbox during long stops ?
Yes. In DSG boxes, the clutch packs are held in near-engaged positions. So if you have your car in D while stopped at a light with the brakes on, it is equivalent to having a manual car stopped, in gear, half clutched with brakes engaged. You'll soon fry your clutch and you'll do the same to the DSG. Except in the case of the DSG, the ensuing repair bill will blow your head off.

If you check your manual, this will be mentioned very clearly in bold letters. I don't remember the exact timings, but I believe that you must shift to N if the stop is more than 5 seconds (or even 2. I'm not exactly sure).

Last edited by ImmortalZ : 22nd March 2009 at 16:09.
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