Towing in overdrive?
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Joined: Aug 2003
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From: Isanti, MN
Camille, I looked into your theory on overdrive transmissions. The transmission bands have absolutely nothing to do with "acting as a big lever" on the rear wheels. They are connected by a driveshaft with two u-joints, therefore, no matter what lateral force you put on the tranny output shaft, the only force that is transmitted is the spinning force! The definition of overdrive is the tranny output shaft spinning faster than the input from the engine. This is caused by a 4th gear ratio of less than 1.
Hope this clears things up!
Hope this clears things up!
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
The bands are what hold the tranny in each individual gear, and they generate heat when they shift. But, the least heat is generated when they do not shift, and this is further compounded by the torque converter locking, which also produces less heat.
A really great article on how automatic trannys work can be found here:
http://auto.howstuffworks.com/automatic-transmission1.htm
A really great article on how automatic trannys work can be found here:
http://auto.howstuffworks.com/automatic-transmission1.htm
Last edited by Tom; Aug 8, 2004 at 10:20 PM.
Super Moderator
Joined: Aug 2003
Posts: 25,479
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From: Isanti, MN
The owners manual to my truck tells me to turn O/D off to avoid excessive shifting. I know when I'm towing a trailer on flat gound, I can hold 70 mph in O/D without it having to downshift to 3rd. I get better fuel efficiency and also keep the engine revs down. When I hit a hilly area, yes, I turn O/D off, because my truck can't tow a trailer up a mountain in O/D, it will shift in and out of O/D, and cause the tranny to overheat.
Posting Guru
Joined: Jan 2004
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From: Hamilton, ohio
just this past weekend i towed my 18 foot ranger bass boat and towed it on the highway with the OD off and on the slower roads where i might be around the speed where OD shifts in and out or when i might be going up alot of hills. my gas mialage was alot better doing this than it would have been driving with OD on or off full time. i was towing it with a 1997 F150 reg cab long bed with a 5.4L, auto trans and 3.55 gears. the most important thing also is to make sure you have a tranny cooler especially if you are going to be towing alot.
