Is it wrong to use neutral w/ an automatic?

[73GMCSprint]

If you notice a difference in engine "load" between Park and Neutral, it's probably the computer limiting the revs. Every newer car I've driven lately does that. It has absolutely nothing to do with load. In Park and Neutral, the torque converter is physically disconnected from any gears, the only difference being the aforementioned pawl inserted into a gear to keep the rest of the drivetrain from turning.

My answer to the original question is this: Putting an automatic in Neutral at ANY speed will not do a thing to the engine or transmission (assuming you don't have your foot on the accelerator and rev the engine through the roof). The equivalent with a manual would be pushing in the clutch pedal. As for having an actual reason for doing so, I can't come up with one, other than needing your car to roll freely.

[prizrak]

Originally Posted by Zuhaib

Well first it will do something, you can screw up parking pawl as it will try to stop the car. And putting it in reverse while moving froward can also cause a whole host of issues. Once or twice its ok, but, you cant say "nothing" will happen.

As for the "feel" vs load on the engine. You might have a lot of vibration in park due to some other issues (I bet others can give input in to that) but I doubt it cause a lot of load on the engine itself.

Totally missed your post somehow. For #1 it depends on the speed, if you are at normal driving speed (30 or so) it will do absolutely nothing, the transmission will absolutely disregard your input. I've done it by accident once, Mythbusters tested it and I had a friend who did the same thing by accident.

If you notice a difference in engine "load" between Park and Neutral, it's probably the computer limiting the revs. Every newer car I've driven lately does that. It has absolutely nothing to do with load. In Park and Neutral, the torque converter is physically disconnected from any gears, the only difference being the aforementioned pawl inserted into a gear to keep the rest of the drivetrain from turning.

I guess it could be that. Still like Neutral better

[Benson]

There's no difference between P and N in my E28 525e as well...

[petarkb]

I'm confused with all the differing opinions in this thread.

Say I'm mad enough to buy a Mazda 323F, then shove a V8+auto box to drive the rear wheels. Could I drive the thing with only the front engine operating, and the rear engine switched off, in neutral?

[sonza68]

That would essentially be like flat towing the car and it isn't recommended for autos. With the engine off, the fluid doesn't circulate properly and can overheat.

[petarkb]

Originally Posted by sonza68

That would essentially be like flat towing the car and it isn't recommended for autos. With the engine off, the fluid doesn't circulate properly and can overheat.

Damn, so it'll have to be awesome, 4WD and twin-engined all the goddamned time.

[thedguy]

Originally Posted by petarkb

Damn, so it'll have to be awesome, 4WD and twin-engined all the goddamned time.

Find a way to drive the fluid with an external/relocated pump or disengage the driveshaft (could use a 4wd manually selectable transfer case to do the job).

[POWERRR!!]

Alright. How about going from R to D while the car is in motion (just coasting, no gas applied) when pulling out from parking? Or going from D straight to R when backing up to park (again, while the car is in motion - no gas applied, just coasting). Will that hurt an automatic?

[Spectre]

Yes, and yes. Over time, you will seriously increase wear on the bands and servos.

Unless you have NO other choice, always come to a complete stop when shifting from reverse to forward or vice versa.

[Hidden_Hunter]

again the question must be asked, why?

What are you going to do with those extra few seconds?

[syncview]

Originally Posted by Hidden_Hunter

again the question must be asked, why?

What are you going to do with those extra few seconds?

Only to say that I was 2.43 seconds faster than YOU.

[Hidden_Hunter]

Originally Posted by syncview

Only to say that I was 2.43 seconds faster than YOU.

then I laugh at you when you have to spend a day rebuilding your transmission

[syncview]

Originally Posted by Hidden_Hunter

then I laugh at you when you have to spend a day rebuilding your transmission

Not me, the mechanics would do that


I dont do that btw.. i have a manual anyways

[prizrak]

Spectre,
I did some testing and seems you were right, I never really allowed the car to stay in P much as I only use it when I park really. I let it idle in P for a bit and then went to N and there really is no difference. Now that I think of it, it was probably only the Buick that did that on me (that car wasn't in very good shape) and I just applied the same logic to other cars never really leaving them in P long enough

[m_weinerich]

The CVT in my car is kinda tricky, being fully computer operated in P when I start the car the engine automatically rises to 2k rpm, if it's hot outside the revs die down to around 1500, if it's winter it will stay at 2k rpm until the car is reasonably warm. Driving the car right after the start up it will stay glued to 2k rpm as long as you have your foot on the gas and doing more than 10mph. Takes 30-40 seconds for the car to warm up and then it drives normally. Going down hills again, computer kicks in u take your foot off the gas and the speed where you were last at will be kept constant, and if not it will slow down a tad, it never speeds up like other conventional autos. And about the neutral, I love coasting in my car, it just goes on forever, I pass cars down hills on the highway in neutral . When you kick it back in D there is a brief lag until the computer adjusts and starts to engine break you, then and only then i press the gas. I've been doing this since the car was new and now at 40000 km's i feel no difference in performance and in the last "nissan comprehensive" service bs all the fluids and tensions were fine.

[Epoq]

This thread is good timing... I actually have a habit of doing this as well, although I do it on the highway and not the parking lot. Just to be clear, I do that only when approaching my exit and there aren't any other cars around so as to not to hold up traffic.

I've read this entire thread thus far and it seems to me that I'm not harming the tranny by doing so since the engine is still running, right? And I always come to a complete stop at the stop sign at the end of the exit ramp before putting it back into gear, so I take it there's no problem there.

As for my reasoning, I'm assuming that I'm saving gas by doing so since switching into N brings the RPMs down from 3300 to 1000. And I like to let the car coast to a slower speeds by itself so that I don't need to apply the brakes as much, hence preserving them. By contrast, some people I know in life wait until the last possible moment and then slam on the brakes to come to a stop. I could practically hear the pads crying and it's not a very safe practice.

Am I still missing something though?

[Spectre]

Yes, yes, you are missing something.

While the transmission is in neutral, most of the rotating parts aren't getting lubrication. Which means that you are starving it for lube if you flip it into neutral while still in motion.

And you're not really saving fuel because at idle the fuel-cut circuit isn't engaged. This is the circuit that cuts all or almost all fuel to the engine when you release the throttle pedal. Instead, the idle fuel circuit is engaged.

Also, PADS ARE CONSUMABLES. CONSUME THEM.

Finally, it's a safety issue. What if you have to suddenly accelerate while "coasting" in neutral? You have to shift into drive, wait for the box to shift and THEN you can accelerate. In the meantime, you have been rear-ended by a giant cargo truck.

[Epoq]

Originally Posted by Spectre

Yes, yes, you are missing something.

While the transmission is in neutral, most of the rotating parts aren't getting lubrication. Which means that you are starving it for lube if you flip it into neutral while still in motion.

And you're not really saving fuel because at idle the fuel-cut circuit isn't engaged. This is the circuit that cuts all or almost all fuel to the engine when you release the throttle pedal. Instead, the idle fuel circuit is engaged.

Also, PADS ARE CONSUMABLES. CONSUME THEM.

Finally, it's a safety issue. What if you have to suddenly accelerate while "coasting" in neutral? You have to shift into drive, wait for the box to shift and THEN you can accelerate. In the meantime, you have been rear-ended by a giant cargo truck.

Hence why I do that when there aren't any other vehicles around. But point taken, I will never do it again! I'm not a very mechanical-minded person you know...

[Hidden_Hunter]

Originally Posted by Epoq

Hence why I do that when there aren't any other vehicles around. But point taken, I will never do it again! I'm not a very mechanical-minded person you know...

It has nothing to do with being mechanically minded, it's just a really dumb thing to do.

[prizrak]

I've done the N coast a couple of times just to see how far my car can coast. Turns out real frigging far, in gear it coasts quite a bit less which is understandable considering that it's basically compression braking all 4 wheels at the same time.

PADS ARE CONSUMABLES. CONSUME THEM.

I second that, pads are much cheaper than transmission parts Also with nice pads they will last you for quite a bit in normal driving so not really a problem.