Greg G

This may be a stupid question but I'm used to driving a stick. I miss shifting but I broke down and got a car that my wife can drive as well since she can't drive a stick. Anyway, when I get to a light it feels so strange to have the car pulling against me. I feel like I'm doing the car harm but I'm sure I'm not. Is it worse to shift to netural since the shifter is not designed to be moved around so much or does it not really matter?

-Greg

rets

You do not need to go back and forth between N and D to "stir the soup". An automatic does not work like that. The fluid is always circulating, as the vanes on the torque converter stir it - the tranny works by the fact that a fluid will act like a fluid up to a point, beyond which iut starts to act like a solid. As the vanes increase in speed, the "stall" speed is reached, and the fluid no slips, but tightens up so to speak, and off you go.

It IS a good idea to put the car in neutral at a long light - just as it is a good idea to not hold the clutch in at a long light. In neutral, the fluid does just sit there, but it is the heat of its movement that causes the ATF to heat up. On neutral, no movement of the fluid by the TQ convereter means less load on the tranny, and load with no outlet usually transfers into heat (like resistance in wire - works great for your stove, but not so great for your speaker where the wasted energy is disipated as heat).

Going back and forth from neutral to D would likely cause more wear, as one can feel a mechanical jolt when it is done, and the motor mounts are tasked more as well.

I have seen people sit for 10 minutes while a huge coal train rumbles by on its way from W. Virginia to Norfolk, to be put on ships. People just sit there, car in drive, brake light on. Only oocassionally do I see someone back off and put the car in neutral. of course, the smartests thing to do is put the car in Park and shut off the engine altogether. The strain of just holding the brake and tranny produce a lot of heat, and excess heat is anathema to long-life.

Pot80h

I was taught never to put my auto into neutral when waiting in traffic. If someone behind were to hit you (God forbid), you're going to move further forward and maybe hit someone else. If the car's in park or you have the brake on (either hand/parking or foot), you won't move as far. Unless you get hit really hard. In which case, it's moot

But no, I never put the car in neutral.

DC5_Integra

Just leave it in D... i wouldn't bother switcing back and forth

Teh Jatt

lol I thought I had problems lol... I do that all the time and then always be afraid that it might hurt the tranny if i kept doing it back and forth.

currage

I put it in Neutral at log stops when I was trying to break in the brake pads. But, not really anymore.

jefffree

In many states it's illegal!

cpurick

I do it all the time. Don't tell Officer Friendly, but sometimes I even coast a little bit. Been doing it that way for years. Been doing my own downshifting for years, too.

Look at that shift gate -- that automatic was made for manual operation.

Yes, automatics depend on a hydraulic system. Aside from that, they operate on a principle that's nearly as simple as a manual. They're tough, with surprisingly few moving parts -- most of which will never wear out.

Xpditor

I don't for lights; I do for trains.

More than two minutes: Yes.

XP

Road Rage

It is illegal to do what - put the car in neutral at a stoplight? That is not true - it is true that coating in neutral is illegal.

RE: being taught to keep the car in gear - that is a great strategy to ensure you and your car take the full brunt of the impact - class must have been taught by the Insurance institute. If you knew you were gonna get hit, and could not accelerate because there is a car in front of you, simple Newtonian pghysics will demonstrate that letting your car sit in neutral, brake off, will result in less impact force to your car than if you are in Park or have the brake on.

RE: the oil pump does not work when the car is in neutral - completely untrue - this sounds like a mechanic with no knowledge who just has to give an answer.

I love some of these responses - they are so amusing.

Here is a good overview of auto trannies to help get some real info in this thread:
http://www.familycar.com/transmission.htm

trube78

If the car that hits you is accelerating then there is a newtonian force. since force equals mass times acceleration. In this case it is actually momentum (mass times velocity) that is transferred. By sitting in neutral with the brake off you will lessen the impact as you will have a collision that approaches an inelastic collision. Since it is unlikely that his car the colliding car will stop but will more likely proceed with you.

However, sitting at a light with your foot off the brake can cause the slow roll forward into the car in front of you -- had someone roll into me in Hawaii -- not a great day. Moreover, you will not have a brake light (or hazard lights) when stopped in the roadway (which is illegal in many states) so if you do get rear ended it is no longer assured to be the other driver's fault.


ATB,
Tom

Pot80h

Actually, I was taught that by both my father and my driving instructor, neither of which worked for insurance (although I did for 4 years) Makes perfect sense to me, having seen so many chain reaction shunts. Didn't mean to cause a dissertation on physical theory

trube78

Pot8oh,
I agree with you, at a light I would stay in drive with foot on brake or maybe in park with foot on brake at a long stop say a train. Where I live, the second you take to get your car in gear as a red light turns to green may result in you being rear ended or chased down for taking too long at the light. (LOL). This is a corrollary to the always put your stick shift car into neutral at a light. There are quite a few folks who swear it is the only way to drive a stick and others who say not to worry. FWIW, my wife got over 300Kmi on a clutch in a SAAB and never put it in neutral at a stop light. She is far better than average with a clutch (better than most guys) though. Not that it proves anything one way or the other.

IRT the physics dissertation, if you are quoting physics to make a point, I think you should quote it correctly. Just my opinion. BTY, talked to my neighbor (state cop) IRT the law. In FL, it is illegal to remain stopped in a roadway without either brake lights or a flasher. He is not and expert but it is the same in at least GA, AL, MI, and his guess is most states which makes sense. The exception is older cars that break down and are not equipped with flashers.
ATB,
Tom

Road Rage

Cars and police must be different where you all live. No one who knows anything about a car leaves the clutch pedal depressed at a long light - it has nothing to do with wearing the clutch out, but it has a lot do do with damaging the throwout bearing. On the S2000 Forum, this isn't even debated.

The other thing is, no one on that Forum has ever mentioned being cited for not having his/her foot on the brakes at a stoplight - which we wouldn't do unless the car were rolling forward or backward. In all the stick cars I have had (24 at last count) over 30 years of driving, i have never been cited, stopped, or received a friendly heads-up from any officer of the law that I needed to have a brake light or flasher on. The one time I did put on my flasher at a stoplight, I got pulled and lectured for using it when there "was no emergency". As i said, law enforcement must be different, but in both cases (auto and stick) it is better for the vehicle to be in neutral - incontrovertibly. And as I said, the "instruction" to keep one's foot on the brakes must have come from an insurance rep, because the physics is also incontrovertible. If car A is in front of me, I am B, and C is approaching B; if B is immovable or reduced in mobility, more energy will be transferred to B than if B is moved from its resting state to speed, V, by C, even if it means that A might also get its bumper mushed a bit. I do not care about car A - but B and C are likely to come out better if my approach is followed. That is Physics 1 at the college I attended, and I do not think the Newtonian Laws have changed, even though the the Laws of police enforcement seem to have changed.

Now, as we approach c, the speed of light, quantum mechanics start to figure in, then there is dark matter, the time/space fabric, perhaps a wormhole or too, well - it gets messy.

youngTL

Road Rage hit it right on. I always put my vehicle in neutral at a very long light. It takes almost no time for the transmission to shift. You'd notice the light turning green (I hope) and then you have plenty of time to get it in gear before the cars in front of you actually start moving. If you're the first one at the light, watching for the other one to go yellow is a good time to put it in gear.

As an aside, I don't believe that coasting in neutral is illegal here. If you're driving a manual and take a long time to shift, or hold your foot down on the clutch while coasting down a hill (not good for the transmission as Road Rage pointed out to hold it a long time), you could always argue that you're in between gears shifting. And how would an officer notice if you were coasting in neutral anyway. And it shouldn't matter whether you do it in an auto or standard.

trube78

As you changed your answer from force to energy it is correct as there is a conservation of energy rule and a conservation of momentum. However, in your first post, you stated impact force which is a misnomer and not IAW Newtonian physics unless there is acceleration involved. I learned that in High School physics. If we decided to approach C, I may be able to follow if you go slow (good pun there.) However I would prefer using one of Einstein's theories of relativity (general or special I always get them confused but I think general) since Quantum Mechanics and Quantum Physics tends to deal specifically with sub atomic particles and the like and well cars are not sub atomic. However, IMO this is not just a simple physics issue.

As to the law, I have not lived in VA for a while (I am a native) but go there often, I will check next time I am in BBURG what the law is but the issue is lights not the status of the transmission. Common sense says if you are stopped in a roadway having a light on is better and yes flashers are only for an emergency in almost all states (and I have lived in quite a few.) I think it is improper signaling (of a stop) in most states. Is it ticketed often, probably not. However, I have zero tickets and warnings on any issue but am reasonably sure I have crossed a few driving laws. I know of no-one who has ever received a coasting ticket either and I know for sure that is against VA law. In one of the notorius VA/MD speed traps (Emporia) they would likely enforce it. Undoubtedly, if you are rear ended while sitting at a light, it may be an insurance issue. Tons of case law where failure to signal/or failure to have working brake lights has mitigated the oncoming cars liability/responsibility in a rear end accident. Found five in a two minute web search.

I actually never said a long light. Is it better for the transmission to shift to neutral/park for a light, likely so particularly for a long light (although if is a short light then there would undoubtly be a point where the shift would put greater wear on the transmission then leaving it in gear.) Without doing a systems analysis I would be hard pressed to define that point. IRT manuals, again it is a time issue. The pressing and releasing of the clutch is when it wears most (assuming you do not ride the clutch or slip it too much to start.) So again there is likely a break even point where the saving of the throw out is negated by excess clutch wear and possibly synchro wear. FWIW, back in my monkey wrench days, I replaced about 20 clutches to every one that needed just a throw out bearing -- maybe different today -- I would have to ask around. However, since 95% of the work is getting to it, if you are doing a clutch change the TO at the same time (and vice versa.)

Aside from the physics issue, there is an actuarial issue IRT not having a Brake on at a light (or being in park). If your car is pushed into a car in front of you, then you obviously damage your front and rear end. I sure the actuaries (as well as safety gurus) can tell if the damage to the car (and personal risk) is more in that case or less than if you are just rear ended. In the worse case, if you are pushed into oncoming crossing traffic well obviously that would suck so ... if we have someone with access to acturary type tables they could answer that. Last time I looked easiest way to total a car was to get it in the front end but worse for safety is the side. Except for exploding gas tanks, rear ending was least damaging. I know that there is a certain amount of physics here, but the front and rear damage may in actuality over ride the physical transfer of energy/momentum. Any ideas from an actuary type fellow?

ATB,
Tom

Mocoso

Leave it in "D" - unless you are stuck behind a 10 minute long train every day (in which case your comute stinks!) the wear and tear on switching fron N to D will most likely cause damage sooner then any excess heat by leaving it in D (and if the tranny cant handle the heat of car being in D without moving then there is some serious design flaws with tranny) on the other hand Im not sure how manu D-N and back transitions they engineer for

As for the police/accident/physics - I rather know that "IF" I happen to see car barreling towards me in rearview mirror that I didnt waste precious time switching from N to D and THEN moving foot from brake to gas pedal - most automatics dont respond immediately from N to D but have a second or so "engagement" dead time - I rather know that second or so is extra time I may have to "maybe" get out of the way (and driving in southern Ca Ive had to get the hell out of the way more then once...)

SpecialFX

Wow, I can't believe all the misinformation and uninformed opinion on such a simple matter. Some have it right, though (Rets). In 20+ years of owning mostly MTs I always would put the trans in neutral when stopped for any length of time. Saves the throwout bearing and other parts. Probably have logged about 600K miles (not on the same car) with only one clutch replaced on a car with a bad motor mount, which contributed greatly to the clutch wear. I've alsop done a lot of miles in ATs. I put the AT in N for long stops also. Definitely saves on heat buildup, which as was pointed out, is the enemy of long life.

One issue I haven't seen raised is brake life. After coming to a stop, sitting with the super hot pads pressed against the rotors leads to more problems, which Honda/Acura is famous for. Some call it warped rotors, though there can be an even longer discussion on that issue. Anyway, drop the car in N and get your foot off the brake if you can. I don't care what people say about the issue. I watch my mirrors and tap the brake if someone is coming up behind me.

gregtomash

I have somewhat related question. During the lunch brake I like to rest in my car for about 40-50 minutes. If it's too cold or too hot I have the engine running and transmission in N (parking brakes applied, of course). I had been doing that with my previous car for 7 years and there were no bad consequences (my son still drives it). I know that I am not alone in this one, but besides wasting gas - is it bad for the car? Appreciate your responses.

SpecialFX

Is this MT or AT? Sounds like AT from your first sentence. Either way the answer is the same. No problem for your tranny. It's basically disengaged from the engine at that point. However, if it's AT why not leave it in P? The bigger issue is letting the motor idle for 40-50 minutes, especially when it's hot.

Although you say you've been doing it for years, I'd worry about engine damage and other problems from excessive heat buildup. With no airflow the engine compartment gets very hot and can lead to early failure of hoses, belts, battery, etc. I know someone who, on hot days, would open the hood of his car to let the heat escape when parked in the driveway after a drive. May be a little (a lot?) over the top. Also, oil pressure at idle is pretty low. Letting it idle for that long period of time may lead to damage to the top end if it does not get enough oil. Not to mention warped aluminum heads, etc. Engines are made to run, not to idle for long periods of time. I would hope this isn't a problem with a well-designed car like ours, but who knows? I don't want to find out.

I wouldn't worry if it's only occasionally, but it sounds like you do it all the time. Having said all that, I can also say that I've done the same thing at times.

Commo

Not too long ago I was in Germany on business. The cool thing that they had was that the stoplights changed from red to yellow and then green kinda to give you a heads up to shift into gear. At least thats my theory because most of the vehicles over there are manuals.

vtechbrain

At a very long stop (ie train) just turn the car off completely. Saves fuel and cuts emmisions. In germany the light turns yellow before it turns green so you will have an interval to crank your car at red lights.

donkeykang

Ok I have an incredibly stupid question. I do this also, but I engage the brakes...I don't understand what you guys are saying by not even holding the brakes and keeping it in neutral. Are you guys saying use the Parking Brake in Neutral or what?

92NSX

What state? I've never heard of such a thing.

Brewmaster

My question is: Is it better to leave it in Drive or move it to Neutral while we watch Road Rage and Trube 78 discuss Physics??

spyfish007

I put the car in neutral. That means I don't have to press the brake as hard.

Repecat

I find the discussions informative and fascinating. Rock on!

jdb8805

I was never really sure whether the tranny received more wear by staying in "D" or by shifting to N then back to D.

The one thing I was sure of was that the brakes/rotors are worn by holding the brake down -- SO

Sometimes I shift to N and sit

Other time I put on the parking brake and leave it in D.


I never use the foot brake.

SpecialFX

Brakes/rotors worn by holding the brake pedal down when stopped?
Wear only occurs when you're using the brakes to slow the vehicle. Or if you have a caliper that's dragging.

Anyway, the real problem, aside from the aforementioned heat buildup in the tranny fluid, is with the hot pads pressed against the rotors when stopped. This can cause the rotors to "warp", though some would argue that the rotors do not actually warp. Rather, the surface becomes affected by the excessive heat in the location of the pads, causing a change in the friction characteristics in those locations. When you apply the brakes the varying friction characteristics on the surface of the rotor cause uneven braking and the resultant shaking of the steering wheel. Resurfacing of the rotors evens out the friction coefficient. I'm sure this may be part of the problem but I've also seen rotors with obvious runnout, so I think warpage is also an issue.

jdb8805: applying th parking brake may not totally prevent the problem since the parking brake simply applies the rear brakes via a cable. Rear brakes are normally less susceptible to warping, however, since they do less work than the fronts. If you can get away with the car in N with no brakes applied, that's the best scenario.

Xpditor

In my view, this is a non-issue for most cars. Stopped in drive with a 5AT, there is some slippage which creates heat which is then dissipated through the cooler under/behind the radiator. The temperature controlled fans then come on and do their job.

I am speaking of a red-light situation. If I am waiting for a long train, I will put it in park and I might even turn off the motor... weather permitting.

Now, I will move this interesting topic to Cars & Bikes since it is not specific to 3rd gen TL and owners of other Acura's might want to get in on it.

tommyy2

I was taught to never hold the clutch down for any period of time. Not only do you wear the throw out bearing but you put tremendous strain on the pressure plate, the strain on the pressure plate causes it to loosen up internally and then it will take more movement before it realeases. As the pressure plate goes bad you notice the clutch pedal seems to engage lower and lower. Eventually with the clutch on the floor you're still grinding gears going into first and reverse (it's no longer totally releasing), and it get's worse from there (more grinding/unable to shift). I only depress the clutch to change gears or go into neutral - never hold it in.

And yea, Germany 1967, red lite/yellow lite/green lite - on your mark/get set/go; and the whole darn country put their cars in neutral when they stopped for the lite.

For an automatic I leave it in drive but I really don't know which is better.

JRock

You guys are forgetting that there is generally already at least one or two cars in line behind you or I at the light before we switch to neutral and take our foot off the brake if the car isn't on a slope. There is no worry about people wondering if you're stopped or your brake lights being on because there are people behind you who are stopped.

NOX 3.2

I don' know if it's illegal or not, but
sometimes if I'm going downhill on a long highway, I switch my 6MT into neutral, it saves a lot of gas and the engine rest...
the brembo brakes still work perfect (in case you wonder about stopping).

what I don't do is stop the car with the gears, as my mechanic told me the brakes are good enough and cheaper to repair than the gearbox... it causes unnecessary wear on the gears.

spyfish007

I'm sorry to say this is wrong. I have done engine tuning in the past so I know something about this topic. When going downhill the engine will go into deep vacuum regions of the ECU map which has LESS fuel than idle conditions. Sometimes it will even cut fuel completely if the rpms are high enough.

NOX 3.2

that's the point.. the rmp are not high , they are alwasy low in neutral. on manual transmissions

spyfish007

even if the rpms are low in the engine is high vacuum area it will still have less fuel than idle. Downhill w/ no throttle is exactly this situation - that is high vacuum. The high rpm info was for fuel cut purposes. You are better off using the engine to brake because it will save fuel.