My car has power brakes and an automatic transmission. I think I may be able to extend the life of my car if I shift into neutral when I come to a stop. My reasoning is that when I apply the power brakes without shifting into neutral I am then using the engine’s power against the engine itself. This would seem to place a strain on the engine, transmission, and brakes. If I shift into neutral at a stop, the engine isn’t straining to move the car and keep it in place at the same time, the brakes aren’t straining against the engine, and the transmission isn’t straining to move the car against the brakes and the engine. I think I can squeeze a significant number of extra miles out my old bucket of bolts (a '91 Ford Escort) by doing this, but a friend of mine says I’d be wasting my time because the extra wear and tear on the car is negligible. Which of us is more nearly correct?
I would think nth is right. Any potential benefit of shifting into neutral while stopped must surely be far outweighed by the cost of shifting a lot more.
It seems to me that the engineers of automatic transmissions have probably made them the best they can possibly be. No driver cleverness needed.
The extra wear and tear is negligible. And, when you shift in and out of Neutral, you are adding some cycling stress to the drivetrain as well - most likely another negligible amount.
I searched, and know of no study that shows any benefit whatsoever to shifting to Neutral in an automatic.
And remember - Neutral isn’t really “Neutral” in an automatic anyways - that’s why they often warn you not to tow the car over 30 mph or so on its drive wheels if it is an automatic in Neutral (not sure if this is universally true anymore, but it used to be).
And, if any difference you might make would likely be negligible, why attempt to defeat the design purpose of your automatic transmission by introducing a manual function?
I’d also like to add that there is no wear an tear on your brakes while you are stopped. The wear and tear comes from the process of stopping when your pads are increasing in pressure against your rotors or your drums.
This is dangerous. You need to be in control of your vehicle in case of an emergency. When that 18 wheeler behind you decides not to stop, you’re not going to have time to put the vehicle into gear. You need to maneuver now.
Actually, when you are standing still at idle, very little engine power is being transmitted to the drive train by the engine and transmission. Until you speed the engine up to pretty good RPM the torque converter that connects engine to transmission, transmits very little torque.
It is reasonable to say that there is no wear on the engine while in ‘drive’ at a stop. The tranny is 'slipping", so to speak, to absorb engine rpms, but not transfer them to the drive wheels. If anything, you could make the arguement that nuetral would increase engine wear, since engine rpm is higher in nuetral.
Brake wear, pumps and all, comes from the 99% of the time the car is being halted from acceleration, not from minimal pressure at stops.
Scratch the though out of your head that transmissions are filled with big metal gears, and those gears grind against eachother.
It’s all done with plates and fluids. A low torque at idle won’t push the plates together and therefore won’t cause wear and tear to anything other than the fluid. Even at idle, some torque is exerted though. So heat can build up. The heat arguments make some sense, if stuck waiting for a superlong train or something. I would think that the force of no torque/low torque switch caused by going from nuetral to drive (you can feel your car doing this) would do more damage to the tranny over time than would keeping it in drive. Sudden changes in torque are the enemy.
The safety argument in favor of being in neutral at a stop light, whether you’re driving an automatic or a manual, is that, if someone bumps you from behind, and your foot slips off the brake and/or clutch (in a manual), your car won’t lurch out into the intersection as quickly, since it won’t be in gear. That’s more likely to occur in a manual, of course, but I think it still applies in an automatic.
The heat arguement doesn’t seem to me like it is necessarily true. The amount of heat that will build up in the transmission is proportional to the torque the engine puts out, times its RPM. If you shift to neutral, the torque won’t change that much (I’m not sure how much it would change, anyway), but the RPM will go up. So, it’s possible that the transmission will absorb more heat in Neutral than in Drive.
The heat issue is a moot point, anyway. The transmission is designed to deal with the heat that gets put into it at crusing at 70 mph all day, by circulating its transmission fluid into the radiator and back. The heat absorbed by the transmission at idle is minimal compared to the heat it absorbs on a highway.
The loading from an engine at idle with the car parked and in Drive isn’t very significant, either. The gears inside will be standing still, carrying a load far below what their maximum capacity is. They don’t start accumulating wear until the gears start moving, which they don’t until the car starts moving. The clutch packs and brake bands, which are usually what wears out on a transmission, should be locked and not slipping, so these will not be picking up any wear either. If they are slipping, the transmission needs to be fixed (or at least re-adjusted) anyway.
Exactly. While Cruising at 70. Radiators are not efficient when sitting still. Which lends to the argument of shifting to nuetral if you are going to be sitting for a while.
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