Any benefit in leaving automatic car in neutral on the stop lights

[nikita7]

Few days ago I spoke to one of my friends who said that he always leaves his lexus in neutral, I said that there is no benefit in it for automatic car. Was I right or wrong ? Thanks.

[alphalanos]

It justs puts more wear and tear on the transmission because you are always making it engage the clutches and disengage them. Brakes hold your car still at a light, and they are much cheaper to replace.

[beef_bourito]

I would say the only advantage to doing it is that there's less strain on the torque converter. other than that there are only downsides.

as previously said, it wears out your transmission. a torque converter is alot easier and cheaper to raplace than auto tranny clutches. another thing is that i think the engine actually uses more fuel in neutral than when stoped in drive. that's because the throttle is at the same place for both but it revs lower in drive then in neutral. so you'd be letting in less air and putting in less fuel and you're not moving so you'r not reaping any kind of benefits.

[curtis73]

Search. The general consensus is that putting any car; automatic or manual - won't save gas, save wear and tear, or give you any more horsepower.

Just drive it like the manual says.

[Akira13126]

Originally Posted by alphalanos

It justs puts more wear and tear on the transmission because you are always making it engage the clutches and disengage them. Brakes hold your car still at a light, and they are much cheaper to replace.

Leaving is drive while at a light doesn't harm the transmission at all. I would think it would do more damage to the piston seals (applies clutches) then to the clutches themselfs. Even then the piston only moves a few thousands of an inch. (somewere around .005 - .010) As for the TC it is always spinning aslong as the engine is running, so that it can continue to drive the trans oil pump. There really no wear on the TC aslong as the trans fluid is kept at the correct level. Just one other note. If the car company felt that it did damage to the trans, they would have designed the engine to shut off while the car is parked. The only two car companies that does this is Toyota (Prius) and the Honda (hybrid). Which are both combnation hybrid cars.



Akira

[Carbon Fibre]

The tourque converter uses flud to transfer power. It has no abrasive qualities per se so it will never wear out. This just wears out likage and bands.

[MagicRat]

Originally Posted by Carbon Fibre

The tourque converter uses flud to transfer power. It has no abrasive qualities per se so it will never wear out. This just wears out likage and bands.

Torque converters do have 3 components that wear out.
There are bearings that can wear out. In a converter they rotate when there is a difference in speed between the converter housing and the impeller. This occurs whenever the engine is running and the converter is not locked up (such as driving at highway speed)

There is also a device in a converter called a 'stator' This is like a second impeller that rotates on a one-way clutch (like a rachet mechanism) This clutch can wear and seize.

Also, all modern torque converters lock up at higher speeds, where the housing and the impeller lock together to reduce friction and drag, so there is a clutch or engagement mechanism that can wear out too.


BTW I occasionally use neutral at a traffic light for 3 good reasons:

1. When a converter is slipping, such as in Drive when stopped, it is building up heat due to the difference in speed between the impeller and housing, When I am towing a trailer and the transmission temp is getting high, putting the trans in neutral reduces the heat that the torque converter is building in the transmission fluid.

2. Two of my old, well-worn cars show low engine oil pressure at idle in Drive, when the engine is at operating temp. Using neutral allows the engine revs to rise about 200 rpm or so, which boosts oil pressure considerably, and (I like to think anyways) may extend the engine life.

3. I get bored at the traffic lights

[Akira13126]

Originally Posted by MagicRat

Torque converters do have 3 components that wear out.
There are bearings that can wear out. In a converter they rotate when there is a difference in speed between the converter housing and the impeller. This occurs whenever the engine is running and the converter is not locked up (such as driving at highway speed)

There is also a device in a converter called a 'stator' This is like a second impeller that rotates on a one-way clutch (like a rachet mechanism) This clutch can wear and seize.

Also, all modern torque converters lock up at higher speeds, where the housing and the impeller lock together to reduce friction and drag, so there is a clutch or engagement mechanism that can wear out too.




1. When a converter is slipping, such as in Drive when stopped, it is building up heat due to the difference in speed between the impeller and housing, When I am towing a trailer and the transmission temp is getting high, putting the trans in neutral reduces the heat that the torque converter is building in the transmission fluid.

The impeller and the case rotate at the same speed. The turbine is the part that spins seprate of the case. Yes they do wear out, but they have to take alot of heat to mess up the bearings. All the stator really does is changes the flow of the fluid to get better tourge multiplacation.(sp) But once up to speed it rotates the same speed as the TC. The stator is the only thing to ever go bad. Sitting at a light there isnt much fluid being moved. TCs make the most heat around 2-3 grand. The lockup style TC only work at steady cruising speeds up around 45+. And all that does is lock the turbine to the TC.


Akira

[MagicRat]

Originally Posted by Akira13126

The stator is the only thing to ever go bad.

Good additional points on TC's.
However, I think you underestimate the havoc that TC's can produce.

Stators do go bad, as you say.
Also bearings do go bad.Again, heat as you say is there worst enemy, but wear gets them too, especially in 'loose' (higher stall) converters.
Lock up mechanisms do go bad.

I have wrecked all these components on several different transmissions, when IMO they were not being abused. Just my luck, right?

[Akira13126]

Originally Posted by MagicRat

I have wrecked all these components on several different transmissions, when IMO they were not being abused. Just my luck, right?

Damn, how do you keep going though them??? I quess it all depends on the cars. It's odd though, my mother drives a 96 subi Legacy right hand drive. So have had the car sense new and it still hasn't gone bad. She delivers mail for a living and uses the car as a daily driver. For about 4 hours a day the car is pretty much idleing. Or another example would be my friends 1983 Honda Accord, no tranny work done at all. Still going strong. I quess just bad luck.


Chris