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Understanding the Automatic Transmission...
Posted by LDH (more from LDH) on Tue, 8 May 2001 23:39:12
In Reply to: Hills, Traffic, and Neutral, Adrian, Tue, 8 May 2001 21:08:59
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The AT is one of the most mysterious automotive components. The big thing in the AT is heat -- you want to avoid it. What's happening when you're stopped at a traffic light in Drive is that the engine still delivers power to the torque converter. The wheels are stopped, so the torque converter must dissipate the energy from the engine. It does this by slipping. The side effect of torque converter slip is heat. So if you're stopped for a long time in drive, you're just heating up the transmission. In this case, it's a great idea to shift into neutral.
The other AT rule is that you never shift in between Park, Neutral, and Drive while the car is moving or the engine is reving above idle. So, you shouldn't shift to neutral on long hills. (Even in a manual transmission car, you wouldn't save gas anyway). The worse part is shifting out of neutral, since the transmission has to re-syncronize from idle to whatever speed you're at. In addition, rolling in neutral heats up the torque converter. This is covered in the manual -- you aren't supposed to tow the car flat (all four wheels on the ground) for more than 50 miles or at speeds over 50mph. Having done this over the last few days will not cause you any permanent damage, so don't worry. Just don't do it in the future.
To sum up, shift to neutral only when you're stopped. Also, if you spend a lot of time in stop and go traffic, you should have your transmission fluid changed at least every 30k miles, I do it every 15k. However, make sure you don't have someone just drain the fluid an put new stuff in. Changing the fluid like that is not acceptable and can actually be bad for the transmission. Check to see that your technician AT LEAST uses a system that actively removes ALL the fluid (ie pumps, compressed air, etc). The best method is full transmission service, which involves dropping and cleaning the pan.
Posts in this Thread:
- Hills, Traffic, and Neutral, Adrian, Tue, 8 May 2001 21:08:59
- Re: Hills, Traffic, and Neutral, Steve L, Wed, 9 May 2001 09:41:23
- Understanding the Automatic Transmission..., LDH, Tue, 8 May 2001 23:39:12 <-- Viewing This Message
- Re: Hills, Traffic, and Neutral, JerryC, Tue, 8 May 2001 23:03:54
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