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post #1 of 13 (permalink) Old 03-22-2006, 07:36 PM Thread Starter
 
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Knowledgeable 4r70w People, enter here..

Hey guys i did a search and really didn't find what i need the answers to.

I want to know if it is bad to do the following and please tell me WHY it's bad etc if you can spare a minute. I've been keeping my car out of overdrive alot lately, i just turn it off and leave it off cause honestly i'd rather have the engine rev alittle more so i have better passing power on the highway doing like 65mph. Overdrive at that speed is like 1900rpms whereas 3rd gear is running like 2300rpms.

Is it bad to do this as far as the tranny is concerned..? In my search i found a guy that said the tranny fluid heats up more when the O/D is off and you're cruising on the highway in 3rd gear..? I know it wastes more gas and basically the engine is being used more, but does it really mess the tranny up staying in 3rd instead of O/D..?

The main reason i leave it out of o/d also is cause i do alot of flooring cause of azzholes on the highway and i know WOT into O/D is BAD. Also is it bad to take the car out of O/D when you're doing like 60mph to let the engine brake for you, or just to step it down so you're in 3rd..?

Thanks.
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post #2 of 13 (permalink) Old 03-22-2006, 08:53 PM
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No it won't hurt it.
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post #3 of 13 (permalink) Old 03-22-2006, 09:03 PM Thread Starter
 
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Perhaps you can be more specific..?
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post #4 of 13 (permalink) Old 03-22-2006, 09:14 PM
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the fluid will get hotter, and hotter fluid does decrease the life of the tranny fluid. on highway id go to od but in the city you can keep it out of od.

biggest killer of trans' is heat and overheated fluid.

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post #5 of 13 (permalink) Old 03-22-2006, 09:22 PM Thread Starter
 
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thanks alot. yeah you know what it is mainly morning driving it's stop and go then plenty of 50mph to 70 spurts to get out of traffic etc. and i always switch the o/d off so i figured let me leave it off completely.

i'll try and leave it on when i'm cruising thanks. i still don't understand how the fluid gets hotter though with only 600 more rpms or around there, i always thought when the tranny is using O/D the tranny is spinning faster then the engine....and leaving it out of O/D works the engine more..but the tranny less. guess i was wrong.
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post #6 of 13 (permalink) Old 03-22-2006, 09:31 PM
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last time down to stlouis for a race, i had to much gas so i figured toss it into od delete to rais rpm and use up some of the gas faster. iv got a tranny temp gauge and i was keeping an eye on it alot and it was at around 18Xish degrees in od out of od it was up around 230-240. thats on the xway at around 70ish

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post #7 of 13 (permalink) Old 03-22-2006, 09:34 PM
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OD is basically 4th gear (although its not actually a gear, its a band). I usually keep my OD off up to 40mph.

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post #8 of 13 (permalink) Old 03-22-2006, 10:14 PM
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If you want to drive with OD off, get a cooler and have at it.
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post #9 of 13 (permalink) Old 03-22-2006, 10:34 PM
 
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Wouldn't 3rd gear run cooler since the planetary gears aren't spinning backwards?
Higher rpm's but the gears are locked as a single unit and l/u is engaged.
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post #10 of 13 (permalink) Old 03-23-2006, 12:28 AM
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If your converter is locked in third gear like my 96, then you will not add much heat to the fluid. If your converter stays open, then you will add more heat. Simple as that.

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post #11 of 13 (permalink) Old 03-23-2006, 03:51 PM
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I would also suspect it runs cooler in 3rd since the planteries are locked. It is the most effiecient gear since it is 1:1, obviously that means less friction, which means less heat.

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post #12 of 13 (permalink) Old 03-23-2006, 03:58 PM
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Majority of the heat is generated by converter slippage.

And yes WOT into OD is bad, but an automatic shift out of 4th is not. Manual 4-2's however, can be, depending on what valvebody you have.
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post #13 of 13 (permalink) Old 03-23-2006, 07:50 PM
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Yes, third gear should run cooler. But get a cooler anyway. The best thing you can do for your transmission is get a cooler.
That is always my number 1 suggestion for anyone with an automatic transmission.

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