Auto trans: Leave it in D or N while waiting at a stop light?
I ♥ Acer
Joined: Mar 2003
Posts: 2,199
From: United States
RE: Auto trans: Leave it in D or N while waiting at a stop light?
ORIGINAL: propellerhead
Let me explain...
I was just reading up on stall converters yesterday and while I was at a long stoplight this afternoon, I was thinking about the engine idling and the flywheel spinning, yet I'm holding down the brake pedal and there's no forward motion. The torque converter is operating below the stall speed so there's very little torque transfered to the driveshaft. All this time, there's a slight load on the engine because the transmission is in gear but the energy is simply wasted as it is converted into heat in the torque converter.
But if I pop the transmission into neutral, the load is removed from the engine and it idles freely. Isn't this less strain on the transmission? Doesn't this mean the liquid coupling is not actively allowing the slip? It's just doing nothing? Isn't it less strain on the engine too? If so, then wouldn't it be better to shift into neutral at long stoplights?
Tranny experts, can you fill in?
Let me explain...
I was just reading up on stall converters yesterday and while I was at a long stoplight this afternoon, I was thinking about the engine idling and the flywheel spinning, yet I'm holding down the brake pedal and there's no forward motion. The torque converter is operating below the stall speed so there's very little torque transfered to the driveshaft. All this time, there's a slight load on the engine because the transmission is in gear but the energy is simply wasted as it is converted into heat in the torque converter.
But if I pop the transmission into neutral, the load is removed from the engine and it idles freely. Isn't this less strain on the transmission? Doesn't this mean the liquid coupling is not actively allowing the slip? It's just doing nothing? Isn't it less strain on the engine too? If so, then wouldn't it be better to shift into neutral at long stoplights?
Tranny experts, can you fill in?
The tranny was designed to have this happen to it, leave it be. Besides, sooner or later you'll accidently slam it, or you're gonna have some pissed off wack behind you because you're not going when the light's moving.
1st Gear Member
Joined: Oct 2003
Posts: 100
From: United States
RE: Auto trans: Leave it in D or N while waiting at a stop light?
I have caught myself lately putting my car in park when at a long light. I just put new brake pads on my car about amonth ago and I noticed I was getting crazy brake fade after a few hard stops. I started thinking about it and if you sit at a light ( in an auto) in drive all you are doing is keeping all that heat on your front brakes. Now I sometimes use park and believe it or not but my brake fade problem has gone away.
4th Gear Member
Joined: Aug 2003
Posts: 1,974
From: United States
RE: Auto trans: Leave it in D or N while waiting at a stop light?
when you are coming to a stop with the auto, release a little pressure off the brake. You don't need as much pressure to stay stopped as you do to stop the car. I drive a stick, and I usually brake hard until about 5mph and then let up on the brakes and roll slowly into the stop, using the brakes just enough. That helps disapate the heat and gases. If you are suffering from major brake fade, it could be fluid, but usually the culprits are improper break in and poor pad choice.
Most people when they put on brakes they go out and stomp on the peddle to see how well it stops. Not what you should be doing. You should be stopping from 20mph with moderate break pressure, letting the brakes cool some, stopping at 30 the same way, on and on to 60mph, making sure to give enough time for the brakes to cool. After that has been done, go fill up the gas tank on the car. Stop with moderate to mild pressure, until the tank is empty. Now you can go a stand on them and brake fade should be almost non-existant for a little longer.
Most people when they put on brakes they go out and stomp on the peddle to see how well it stops. Not what you should be doing. You should be stopping from 20mph with moderate break pressure, letting the brakes cool some, stopping at 30 the same way, on and on to 60mph, making sure to give enough time for the brakes to cool. After that has been done, go fill up the gas tank on the car. Stop with moderate to mild pressure, until the tank is empty. Now you can go a stand on them and brake fade should be almost non-existant for a little longer.
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