Auto - Does leaving it in "D" damage the gearbox?

[paddyhasneeds]

No doubt a bell-end ish question to many, but I've not driven an auto since my old 190E days.

In a modern auto, unless you are actually parking (or going backwards I guess ) is there ever any benefit in taking it out of "D", other [scrooge mcduck]than perhaps making your brake bulbs last a little longer[/scrooge mcduck]?

[anonymous-user]

I assume you mean when at a standstill at a red light for example. From a technical point of view I doubt it does any harm whatsoever, from a PH point of view someone will be on in a sec to point of that your brake lights being on will permanently blind the person behind, before actually melting their eyeballs out of their skull with the intense brightness

[Dimski]

I always knocked mine into N and applied the parking brake.

No idea if it caused less wear, or gearbox oil to get a bit hot, just thought it was good practice.

Then my parking brake motor failed.

[Herbs]

I believe they are designed to be left in drive. I've also heard they use less petrol rather than move into N although I have no idea how accurate that actually is!

[GKP]

You'll actually do more damge (although negliible either way) to continually knock it into N and back into D at traffic lights.

[bull996]

I always knock mine into N, just to save the brake discs.

Leaving your foot on the brake when the discs are hot is the fastest way to warped discs (or discs with deposits on, which ever theory you subscibe to).

[Harry Monk]

Dimski said:

I always knocked mine into N and applied the parking brake.

Wouldn't knocking it into P have a similar effect?

[anonymous-user]

Putting it in P in traffic is a VERY bad idea - if someone rear ends you you are liable to end up with bits of the parking pawl destroying the box. As for the original question, I don't think it makes much difference really although I have long suspected that sitting on the brakes after stopping encourages disc warping/deposits/wobblyness.

Dave

[Countdown]

Isn't leaving it in "D" akin to slipping the clutch in a manual?

[Don1]

I notice in the Range Rover that knocking it into N at the lights does make a real difference to the car - in D it's constantly trying to drag itself forward against the brakes.

[Matt80M]

I always knock mine into N at the lights - I can't say I always apply the handbrake - sometimes a I do, sometimes I don't. I've never been actually blinded by someones brake lights.

It feels like you are putting less stress on the drivetrain when it's not trying to push against the brakes.

[EDLT]

Harry Monk said:

Dimski said:

I always knocked mine into N and applied the parking brake.

Wouldn't knocking it into P have a similar effect?

If you leave the car in P without the parking brake on the car will roll a little (unless the road is perfectly flat) which puts strain on the parking pawl.

Also going from D to P usually means going through reverse which is alarming for the people behind you.

P is supposed to be the auto equivalent of leaving a manual car in gear (in case the handbrake fails).

[Monkeylegend]

Mine has an optional hold facility which applies the brakes automatically whan stopped at traffic lights etc. This only works when it is left in "D" so can't imagine it does any harm whatsoever.

[WeirdNeville]

Countdown said:

Isn't leaving it in "D" akin to slipping the clutch in a manual?

Not with a torque converter, no. It's akin to stirring a bowl of porridge.

[dylan0451]

i was under the impression it puts load on the torque converter and eventually fries the fluid or damages other components TC components. i'm guessing doing this a lot, or for long periods of time while stationary must warm things up a little seeing as there's no heat dissipation

although, thinking about it, don't auto's have an external cooler? still not much use if it's only passively cooled

Edited by dylan0451 on Monday 24th January 19:12

[astonluv]

Living in a nation where automatic is king, the practice is that the vehicle stays in D until you actually get out of your vehicle. This includes not only traffic lights, but long stints at railway crossings and in traffic jams. We are told that that practice is hard on the transmission and when stationary and for long periods the vehicle should be knocked into N. However, no-one EVER takes their feet of the brakes unless the vehicle is in motion and those of you who have travelled in North America know what I am talking about.

[IceBoy]

Knock it into N when you know that your are going to be stationary for more than 60 secs.

That's what I do, again not sure if this is good or bad but it certainly feels right. The car is not eager to move and the whole drive-train/car becomes "relaxed"

IceBoy

[gizlaroc]

Don't mist autos have a hold feature now? Press the brake hard when stopped and it will sit there until you it the brake again or the accelerator. My last few have had this.

[David87]

I stick them in N and apply the handbrake, just as I would in a manual car when at traffic lights etc.

[eliot]

dylan0451 said:

i was under the impression it puts load on the torque converter and eventually fries the fluid or damages other components TC components. i'm guessing doing this a lot, or for long periods of time while stationary must warm things up a little seeing as there's no heat dissipation

although, thinking about it, don't auto's have an external cooler? still not much use if it's only passively cooled

Edited by dylan0451 on Monday 24th January 19:12

Leaving at idle in park for short times (traffic lights etc) is fine. If you sit there with your foot on the brake and holding the revs at 2500rpm, you are loading the torque converter and heating the oil up - but you wouldn't normally do that, apart from at santpod.