[Aravind_M92]

Bringing on the age old debate on automatics. When at a red light or conditions where you’re idling your car, which should be done?
- Leave the car in D with your foot on the brake
- Slot into neutral (when on a level surface)

There have been a lot of points debating which practice is good.
In case if the car is kept in D with foot on the brake, it does strain the engine, transmission and the the brake. I imagine this scenario to be like a dog tied to a leash trying to run away while the owner is restraining him to do so. Here both the dog (engine), leash (transmission) and the owner (brake) are at strain.

Coming to the other scenario. Slotting the car into N while at signals removes the strain on all the three components. But once the signal turns, when it is slotted to D mode, the engine takes a toll on the Torque Converter. But the other components wear is comparatively lower.

I usually slot into N when stopping at signals. Given this again I’m confused!

P.S. Can we have a poll on this topic on the practice our members do?

[echo77]

Originally Posted by Aravind_M92

Bringing on the age old debate on automatics. When at a red light or conditions where you’re idling your car, which should be done?
- Leave the car in D with your foot on the brake
- Slot into neutral (when on a level surface)

There have been a lot of points debating which practice is good.
In case if the car is kept in D with foot on the brake, it does strain the engine, transmission and the the brake. I imagine this scenario to be like a dog tied to a leash trying to run away while the owner is restraining him to do so. Here both the dog (engine), leash (transmission) and the owner (brake) are at strain.

Coming to the other scenario. Slotting the car into N while at signals removes the strain on all the three components. But once the signal turns, when it is slotted to D mode, the engine takes a toll on the Torque Converter. But the other components wear is comparatively lower.

I usually slot into N when stopping at signals. Given this again I’m confused!

P.S. Can we have a poll on this topic on the practice our members do?

In my Honda City (2010) I noticed that there is a slight increase in RPM (needle moves just above 1k RPM) when slotted into N when stopped, than keeping it in D (needle is below 1k RPM). I know this is strange as we would expect it to be more RPM in D+idle than N.

In both cases, I need to use the brakes, so I just keep it in D for short/regular stops. If it is a long stop, I may slot into N or sometimes slot it into P.

Do brake pads wear out once you are completely stopped in D?

There is another thread on this specific topic: https://www.team-bhp.com/forum/techn...ic-lights.html (Automatics : P or N at signals / traffic lights?)

[Jeroen]

These days keeping your automatic in D during stops is no problem at all.

Brakes don’t wear when you are at full stop.
The engine only works marginally more at full stop in D then at idle in N. The slow drop in RPM is not unusual, when engaging D. The engine needs to produce a little bit more torque than at idle, just enough to drop the RPMs a bit. On more fancy car the effect is near zero change. It’s all down to how well the ECU can keep the RPM stable during a load shift at idle. The effect you see could be be bigger when your engine is not up to normal operating temperature as well.

Nothing to worry about. Also the ‘extra load” is very little, so absolutely nothing that will cause wear on the engine.

On some cars you might see a similar effect when the AC switches on, with the engine idling.

When standing still with the transmission in D there is nothing that can wear. At least nothing mechanically. At these low RPMs the transmission fluid in the convertor is pumped around at a very sedate pace. In theory it will warm up a bit. It is only when the transmission fluid would overheat it becomes a problem. Because that will affect the quality and duration of the fluid.

These days with modern auto-boxes/convertors and high quality transmission fluids it is really not an issue at all. In theory very high ambient temperatures, with very old transmission problems could maybe cause problems.

But as a rule, these days keeping your foot on the brake and the transmission in D is not a problem at all. Even for prolonged periods of time. Putting the car in N, is in theory better, but doubtful if you could measure the effects in real life.

It is more about about convenience and what practice you feel comfortable with.
As a rule I keep my automatic in drive at traffic lights, light congestion etc. Only when I see it coming I will be stuck for a longer period of time, will I switch to N. Not so much because I am worried about any wear or tear, but just because I want to release the brake!

Obviously, all of the above is valid for traditional aut-box with convertors only. CVT and the likes such as DGS is a different story.

Jeroen

[locusjag]

I and another fellow member are facing a shuddering from our A Star Torque Converter Automatics. Sorry for going somewhat off-topic here, but I would really appreciate any pointers.

The symptoms:
* A shudder in "P" mode sometimes just after starting the engine. At other times, my front passenger seat's headrest can be seen vibrating vigorously when the car is still in "P" gear a few seconds after starting the car.
* A shudder and hesitation to move in reverse just after slotting into "R" gear; my foot will have just lifted off from the brake at that point (could it be faulty brake boosters since I'm lifting off from the brake?)
* A rattling sound when the car is at a complete stop in "D" gear and I'm stomping on the brake

The suspects
* Weak Automatic Transmission Fluid - Unlikely suspect since both I and the other member in question have drained and replaced the ATF in the past year. Moreover, the other member has monitored the ATF temperature with a good OBD scanner. Everything seems ok for him.
* Worn engine/transmission mount - I did plough the car into a deep pothole at 50 kmph once and this shuddering has surfaced beyond that event only. It could be a coincidence though.
* Faulty spark plug - Unlikely since the car hasn't been misfiring for either of us
* Choked throttle body (i.e., perhaps it needs cleaning)?
* Faulty brake booster - Unlikely suspect because the shuddering is also felt when the brakes aren't in play

[Jeroen]

Originally Posted by locusjag

I and another fellow member are facing a shuddering from our A Star Torque Converter Automatics. Sorry for going somewhat off-topic here, but I would really appreciate any pointers.

I doubt it will be the brakes. The first suspect and also easily checked is the engine and transmission mounts. All your symptoms can be explained.

If all the mounts are ok, the next thing is to try and look at the transmission.

Good luck
Jeroen

[Aravind_M92]

Originally Posted by Jeroen

Obviously, all of the above is valid for traditional aut-box with convertors only. CVT and the likes such as DGS is a different story.

Jeroen

Sir what has to be done in CVT and DCT? Have cars from various transmissions at home. It's clear with AMTs and ATs. Kindly clarify with the other two. N and brake or D and brake at short interval stops? This really is a confusing debate. I always thought The N or P disconnects the engine from the torque converter. And at short holding intervals this helps better than keeping a foot on the brake

[Jeroen]

Originally Posted by Aravind_M92

Sir what has to be done in CVT and DCT? Have cars from various transmissions at home. It's clear with AMTs and ATs. Kindly clarify with the other two. N and brake or D and brake at short interval stops? This really is a confusing debate. I always thought The N or P disconnects the engine from the torque converter. And at short holding intervals this helps better than keeping a foot on the brake

One of the interesting features of a CVT is that with the engine idling the car does not creep forward. For some people that is very appealing. (E.g. my mom! She did not like the idea of a car moving forward without her stepping on the accelerator)

So if you have a car with a CVT and it does not move when idling, you can rest assured; all transmission components are at rest. On most CVTs there is a primary clutch, that disengages at low (idle) engine rpm. So whether you put the brake on, put your hand brake on, makes no difference as such. (Although putting a hand brake on at a traffic light in considered bad practice in case you get hit.

Or in practice, just putting your foot on the brake whilst waiting at a traffic light in a car with CVT is perfectly fine.

When it comes to DCT there are quite a few variations out there, from different manufacturers. Having a wet or a dry clutch might make a bit of a difference.

But have a look at our excellent thread on DSG ( https://www.team-bhp.com/forum/techn...t-gearbox.html (DSG, demystified! All you need to know about VW's Direct-Shift Gearbox) )

You will see that the advise is to shift to N whilst waiting.

if all fails; check the owners manual!

Jeroen

[SoumenD]

Originally Posted by Minardi

One thing I wanted to know...when you stop at the red light, you still keep the gear on 'D' and put your foot on the brake or do you put the gear on 'P'?

Just switch to 'N' at signal stops. If you keep it at 'D' without brakes , car would move upto 7kmph approx. So switch to N and pull the handbrake.

Originally Posted by Minardi

Can the gear change be controlled indirectly through the speed at which you press the accelerate? I though I read somewhere, if you press the accelerator suddenly, then the auto will shift down to give you that 'surge'. Is this true?

Yes you can regulate the 'steps' with throttle inputs. Half throttle it gently and gears would regulate smoothly. Go hard on the throttle and all you get initially is rubberband effect i.e. a lot of noise followed by gradual increase in speed (not a good way of driving CVTs).

Originally Posted by turbo_lover

When you are at a red light u can keep the gear select at (D) if you dont have your foot on the gas pedal the car will not move forward .

Nop. Honda CVTs have kinda creep function. It would move if it's left at D even if your foot is off the gas pedal

[supremeBaleno]

Originally Posted by Aravind_M92

When at a red light or conditions where you’re idling your car, which should be done?
- Leave the car in D with your foot on the brake
- Slot into neutral (when on a level surface)

Either is fine. While most AT drivers leave the car in D with foot on brake, those with OCD (like me ) would slot to N with foot on brake at traffic lights.
But if it is a kind of big traffic jam that would take long, I would engage handbrake and put in P.

Originally Posted by Jeroen

One of the interesting features of a CVT is that with the engine idling the car does not creep forward.

When in D mode ? AFAIK, creep in D is common to TC, CVT, AMTs. No idea about other ATs.

[shamanth]

Originally Posted by shipnil

Is there a way disable creep feature in Drive mode in automatics?

That would make proper AT car behave like AMT, in AMT with no hill-assist(new Nexon top-end has hill-assist) during incline, the car would roll back couple of seconds before it starts to creep, so imagine in bumper to bumper city traffic, it will hit back two wheeler or Autos who would have stopped next to your rear bumper, and then move forward.

So AMT guys use either hand-brake or left-leg on the brake to move out of inclined traffic stop, giving accelerator and then removing brake.

So if they remove creep feature for AT car, you will need to use break, then accelerate and then to move ahead in incline stop and go traffic.

[GrandTourer]

Originally Posted by Aravind_M92

Bringing on the age old debate on automatics. When at a red light or conditions where you’re idling your car, which should be done?
- Leave the car in D with your foot on the brake
- Slot into neutral (when on a level surface)

This YouTube channel explains all things cars in a very intuitive and scientific way.
Please watch this video to understand whether you should slot into N or keep in D.

https://www.youtube.com/watch?v=6zzEtxJkC7Y

TL;DR - Keep it in D mode at Red lights. Modern cars cut off the engine from the transmission when enough pressure is applied to the brake. The amount of pressure it takes for the brake to bring the car to a stop is enough to cut off the engine from the transmission.

[ag408]

Thanks for the video. We are all talking about the car moving forward in D. What about sliding backward? Will that happen with D or N engaged of the is a mild slope? Or does the AT take care of that??

Originally Posted by GrandTourer

This YouTube channel explains all things cars in a very intuitive and scientific way.
Please watch this video to understand whether you should slot into N or keep in D.
https://www.Youtube.com/watch?v=6zzEtxJkC7Y


TL;DR - Keep it in D mode at Red lights. Modern cars cut off the engine from the transmission when enough pressure is applied to the brake. The amount of pressure it takes for the brake to bring the car to a stop is enough to cut off the engine from the transmission.

[SCORPION]

Originally Posted by ag408

Thanks for the video. We are all talking about the car moving forward in D. What about sliding backward? Will that happen with D or N engaged of the is a mild slope? Or does the AT take care of that??

In N, it will definitely roll backwards on a slope. In D, if the gradient of the slope is beyond what the crawl feature can handle, it will start rolling backwards. Some cars have hill hold assist to take care of that. The brakes will remain engaged for a brief period allowing you to move your foot safely from the Brake pedal to the Accelerator pedal.

[kushagra452]

If the stop at the traffic signal is more than 60 secs I switch off the engine. If the stop is going to less than 60 secs then I slot the gear into neutral and engage the hand brake. Kindly note, I drive a Swift AMT.

[ag408]

Thanks, but still what's the solution to that? Can we keep the hill hold switched on at all times?

[ QUOTE=SCORPION;4979150]In N, it will definitely roll backwards on a slope. In D, if the gradient of the slope is beyond what the crawl feature can handle, it will start rolling backwards. Some cars have hill hold assist to take care of that. The brakes will remain engaged for a brief period allowing you to move your foot safely from the Brake pedal to the Accelerator pedal.[/quote]