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Old 18th April 2017, 09:28   #31
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by blackasta View Post
The book - follow the book.

P<->N shifting without pressing the button actually prevents inadvertent shift to R while the car is in motion, which can be catastrophic for a gearbox.
If you are shifting between P<->N by pressing the button, you are actually increasing the chances of the aforementioned to happen.
I guess you meant D <-> N, as one cannot shift from P <-> N without pressing the button.
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Old 18th April 2017, 09:35   #32
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by MAS View Post
I guess you meant D <-> N, as one cannot shift from P <-> N without pressing the button.
My bad - yes D<->N should be read in place of P<->N.
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Old 18th April 2017, 10:08   #33
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by Prodigy07 View Post
Quick question to CVT users.

When you shift from D to N and vice versa, do you press the lever on the gear while shifting? Can we shift without pressing that lever?

Please share your inputs.
Yes we can shift without pressing the shift button. The Baleno's user manual says we need to press the button while shifting to P, R and L.

Shifting to N and D can be done by just moving the gear lever.

For the record, I shift to N + handbrake while stopped at signals that are longer than 10 seconds or so.
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Old 18th April 2017, 10:39   #34
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Default Re: Automatics : P or N at signals / traffic lights?

Similarly on "gated" shifters there is no gate between N and D; the shifter moves straight Up/Down between N and D. This is similar to not having to press a button on non-gated shifter.

So non-gated shifter do not use button to shift between D <> N or N <>D. If you press the button while shifting from D to N you might shift straight to R instead of stopping at D if you were not to use the button.

So don't listen to Honda dealer personnel, stick with Honda user manual recommendation.
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Old 18th April 2017, 11:12   #35
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Default Re: Automatics : P or N at signals / traffic lights?

Renault Qwid AMT: The car won't move forward in 'D' mode unless you press the accelerator. So you can easily wait in 'D' mode at a red signal.
Maruti Alto AMT: Waiting in 'D' mode at a red signal will wear out the clutch, because the car would try to move forward by slipping the clutch.
Torque Converter Automatics: The torque convertor pushes the 'wheel side of the transmission' by pumping the transmission fluid, so in effect there is no slippage when you wait in 'D' mode with your right foot on the brakes. You will in fact wear out the 'transmission clutch set' faster if you shift back and forth between 'N' and 'D' frequently.

Last edited by jinojohnt : 18th April 2017 at 11:17.
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Old 19th April 2017, 10:37   #36
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by jinojohnt View Post
Torque Converter Automatics: The torque convertor pushes the 'wheel side of the transmission' by pumping the transmission fluid, so in effect there is no slippage when you wait in 'D' mode with your right foot on the brakes. You will in fact wear out the 'transmission clutch set' faster if you shift back and forth between 'N' and 'D' frequently.
I dont understand how this can happen- most folks will shift from D to N only when the vehicle is completely stationary. In that case, how is the clutch getting affected ? Is it not similar to shifting from a gear to N, like in MT cars?
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Old 19th April 2017, 15:07   #37
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by BUXX View Post
I dont understand how this can happen- most folks will shift from D to N only when the vehicle is completely stationary. In that case, how is the clutch getting affected ? Is it not similar to shifting from a gear to N, like in MT cars?
Since the engine side is always running (resulting in a 'push' to the transmission), there is always an un-noticeable jerk when you shift from 'N' to 'D'. This results in a small yet significant wear of clutch when the gear set locks to (internal) first gear. The torque converter can only minimize this jerk, but not completely avoid it.

On the other hand, there is almost nil clutch wear when in 'D' mode with your foot on the brakes, because the clutch set is already locked on the correct gear with no additional slippage.

Last edited by jinojohnt : 19th April 2017 at 15:10.
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Old 19th April 2017, 16:27   #38
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Default Re: Automatics : P or N at signals / traffic lights?

I've been driving a Honda Civic with a 5 speed torque converter automatic transmission for the last 7 years. Here is what the manual says.

Park (P) - This position mechanically locks the transmission. Use Park whenever you are turning off or starting the engine. To shift out of Park, you must press on the brake pedal and have your foot off the accelerator pedal. Press the release button on the front of the shift lever to move it.To avoid transmission damage, come to a complete stop before shifting into Park

Neutral (N) - Use neutral if you need to restart a stalled engine, or if it is necessary to stop briefly with the engine idling. Shift to the Park position if you need to leave your vehicle for any reason. Press on the brake pedal when you are moving the shift lever from neutral to another gear.

The manual is very clear what to do when it comes to torque converters. It's okay to keep it in D with your foot on the brake when you are stopping very briefly but I always shift to neutral and use a handbrake if the stop exceeds 10 seconds or so.

On the Civic, the gear shift does not come out of park or go to park without using the button in the shift lever. It goes from N to D and back without pressing the button.

TL;DR: Read the manual
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Old 19th April 2017, 17:13   #39
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Default Re: Automatics : P or N at signals / traffic lights?

When we put a car in P, the transmission is locked. If someone rear ends you while you are waiting at a signal with the transmission in P, it can potentially lead to a pretty hefty bill to rebuild the transmission depending on the transmission type.

The general rule to follow is to put the transmission in N and pull the hand brake for long stops. For short stops, just brakes are sufficient. However many cars are smart. In both my V40 and Polo which have dual clutch transmissions, the mechatronics unit disengages the output shaft when we come to a complete halt with the foot brake pressed. So D+Brake is equivalent to N+Brake. However I shift to N at long stops by habit. In DCT/DSG boxes, one can feel the clutch biting and the output shaft re-engaging when we press the loud pedal.

Last edited by reignofchaos : 19th April 2017 at 17:16.
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Old 19th April 2017, 23:54   #40
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by funkydevil View Post
Putting the car on D at signals only keeps the car in gear and will wear your brake pads faster.
Quote:
Originally Posted by androdev View Post
Realistically, transmission wear is not so bad that you would incur expenses due to stopping in D mode. I would be more concerned about brake lights and brake pads which have much shorter life if care is not taken. -)
Brake pads donít really wear when the car is stationary.

Quote:
Originally Posted by androdev View Post
P mode is same as N mode with transmission locked with a mechanical 'pin'. Should not be used without locking the wheels with brake because this 'pin' can wear and break. Trying to hold the car at stop with P mode is equivalent to stopping the car with a 'pin' that locks the transmission shaft. Can put a lot of stress on this pin if the car is on incline ,etc. so P mode should always used with brakes just like N mode. I would like to think that P mode doesn't exist for the driver and it is just meant for the car's computer to use P when you switch off, AT breakdown, etc.
)
So here is a picture of this mechanical pin, known as pal. It fits very snuggly into a meshed gearing wheel.

Automatics : P or N at signals / traffic lights?-p4082906.jpg

I attended a workshop just last week at a Jaguar specialist who also specialises in overhauling autotransmissions. Obviously, Jaguar but he gets work from Mercedes, BMW, Audi, Porsche dealers and a few others as well. Also, he is a forensic investigator for various car insurances.

He actually discussed the case where a BMW owner made a claim on his insurance. His car had been rear ended by a truck and dragged across the road for about 15 meters. Obviously, there was a lot of damage. In addition the owner claimed the auto transmission was damaged as well. So the insurance called Raymond and send him the transmission.

He told us it would be extremely rare for a transmission to get damaged by a rear end, no matter how severe. This particular box had all sorts of problems, none related to the car being in parked whilst rear ended.

Here some more information on this story and transmission in general:

http://www.team-bhp.com/forum/diy-do...ml#post4180547 (My Car Hobby: A lot of fiddling, and some driving too! Jaguar XJR, Mercedes W123 & Alfa Romeo Spider)

We actually did ask Raymond about what damages could/do happen when you leave an autobox in D and keep the car on the brake. According to him, again, you need to get real unlucky before anything happens. Ambient temperature (say well above 40oC) and a box that has never had a refresh is a combination that could give problems. But not within seconds, or minutes. You would have to hold it for 15-20 minutes at least, or repeatedly for many intervals. Under those circumstances you could actually boil the transmission fluid. Transmission fluids, like lubrication oils are full of dopes. These dopes do deteriorate over time. They all do and that is one of the main reason there is simply no such thing as an autobox sealed for life (Even though Jaguar will still sell you one!). All boxes at some point in time need a flush to get rid of all debris and dirt and a re-fill.

The older the transmission fluid the more likely it is to give problems, especially at higher temperatures. Simple draining and re-filling is just about the worse you can do to an autobox. (See the example in my thread). On the upside, it would be very rare to damage anything even if the transmission is running very very hot. Even the brain and all other parts should have no problems with those high temperatures. So as soon as you manage to get a flush and a refill everything is likely to work as before again.

Even so, I do believe you should never put your car in P until you are actually parked, i.e. not participating in traffic anymore. My Jaguar still has the gorgeous J-gate. I can switch between D and N and vice versus with a little flick of my wrist. Donít need the brake or push any buttons. Works great!

Jeroen

Last edited by Aditya : 20th April 2017 at 09:48. Reason: Uploading image as attachment
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Old 20th April 2017, 09:51   #41
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Default Re: Automatics : P or N at signals / traffic lights?

^^ Thanks for that explanation . But that still does not answer if D+Brakes is better than N+Brakes, while stopping at a traffic signal .
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Old 20th April 2017, 10:31   #42
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by Jeroen View Post
.. My Jaguar still has the gorgeous J-gate.
Thanks for the detailed explanation.

The gates also have their own branding, is it? Hyundai calls it H-gate

Quote:
Originally Posted by BUXX View Post
^^ Thanks for that explanation . But that still does not answer if D+Brakes is better than N+Brakes, while stopping at a traffic signal .
Quote:
Ambient temperature (say well above 40oC) and a box that has never had a refresh is a combination that could give problems. But not within seconds, or minutes. You would have to hold it for 15-20 minutes at least, or repeatedly for many intervals. Under those circumstances you could actually boil the transmission fluid.
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Old 20th April 2017, 11:29   #43
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by BUXX View Post
^^ Thanks for that explanation . But that still does not answer if D+Brakes is better than N+Brakes, while stopping at a traffic signal .
From the transmission point of view, not much difference between them, unless it’s very hot and you drive a car with 150.000km on the clock that has never had a tranny flush and you need to hold it on the brakes for a very long time in which case you better go for N+ Brakes.

I usually switch to N unless I expect to be able to drive on within a very short space of time. So there is no “better” as such. Mostly preference.

Quote:
Originally Posted by Nonstop-driver View Post
The gates also have their own branding, is it? Hyundai calls it H-gate
Did not know that, I’m only familiar with the term J-gate of Jaguar. Do you mean that Hyundai has an automatic gear selector that follows a H-pattern? Seems weird. H pattern is of course the more or less standardised pattern for manual gear boxes (from the time we only had 4 gears, neutral and reverse)



Another little anorak fact I picked up at this workshop: It’s good practice to use all the manual gears now and then. Sufficient to pull away in 2nd, keep it there for 10 seconds of so, move to 3rd, keep it there for 10 seconds and so on until you have gone through all manual selectable gears.

When you select a gear manual, the brain will open up all (most) of it valves simultaneously. Which means a lot of transmission fluid is going to get pushed around your box. So it’s a good way to “flush’ out any dirt that might have collected on the friction plates and other bits. Do this once a month or so.

( I have never done this in all my years of driving. But Raymond showed us how it actually worked and it does make sense. If anything it won’t harm anything so I have now taken to do so. Done it once, next month again and onwards!)

Jeroen

Last edited by Jeroen : 20th April 2017 at 11:30.
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Old 20th April 2017, 11:36   #44
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Default Re: Automatics : P or N at signals / traffic lights?

I own a 2015 Jetta TDI AT and always use 'P' only when the car is parked.

At signals I simply slot to 'N' and engage the hand brake and relax.
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Old 20th April 2017, 12:06   #45
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Default Re: Automatics : P or N at signals / traffic lights?

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Originally Posted by Jeroen View Post

Did not know that, Iím only familiar with the term J-gate of Jaguar. Do you mean that Hyundai has an automatic gear selector that follows a H-pattern? Seems weird.
Oh. No no. I was referring to this
Quote:
My Jaguar still has the gorgeous J-gate. I can switch between D and N and vice versus with a little flick of my wrist. Donít need the brake or push any buttons. Works great!
Hyundai's have this mechanism that will block you from accidently slotting in reverse while trying to slot from D to N. That's the H gate I was referring to.
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