O D off?

[Lincolns Own]

yeh, i always thought that if u left the overdrive off for long periods of time that it could damage the trans (read in manual i think). but i was driving with my friend in his nissan and he said having it on can screw your car up. he knows more about engines and stuff then me, but the car has 121k overdrive ON miles on it and the trans is perfect.

my real question is...

does having the overdrive off cause any problems in the short or long runs?

thanks for input

 

[klutch]

It just runs high rpms I always keep overdrive off when im going below 50 because otherwise especially in city driving it will go in and out of overdrive which is harder on it

 

[Dominus]

Screw your car up? Oh please. I have owned many cars that have gone over 200k miles with their overdrive transmissions and have never seen a period of overdrive off.

Having the overdrive off will cause a problem alright. First of all, your fuel economy will go down the hole because your engine will be constantly turning faster. This will REALLY get you when cruising at anything above 45 mph. Secondly, you're making your engine do extra work for nothing all that time.

There's a reason why classic car owners will kill for a Gear Vendors or Kiesler tranny swap. It's because overdrive is a priceless thing to have.

 

[thamarkman]

Its all about how you drive. If you're often going between 35-40 and you car is shifting in and out of OD all the time then its bad for it. Personally I like the sportiness that third gear has to offer when I'm going below 50. Overdrive is for the freeway, most tranny people will tell you that.

 

[torquemonkey]

I agree w/ klutch

The "bad";
Do you live in an area that has a lot of hills, large or small? Drive w/ your AC on pretty much all the time in stop and go traffic?
The "good";
Do you use your vehicle on flat highways? Not much traffic to and from?

I'm thinking that your buddy is talking about "lugging" your engine. The key to understanding this is, understanding "Load". Low RPMs w/ high load is not at all good for the car/truck (any motor or engine). As you spin the engine faster it produces more power and is "stronger" with respect that, the engine can handle the load more efficiently. Your mechanically driven oil pump is RPM dependent; this pressurizes the oil passages around your bearings. The same oil that is the "cushion" around your crankshaft main journals. Your ECM senses the additional load, adds more fuel to compensate. More fuel burns in the combustion chamber, pushing harder against the oil cushion around your crank and will increase "wear". Also this will tax the cooling system. It too is RPM dependant. The less the engine spins, the less coolant flows. This taxes the system. The engine will run hotter, the oil gets thinner = less protection.

Your tranny shifting in and out of O/D is not healthy. This ought to be self-explanatory.

Each vehicle has its own unique design characteristics and flaws. Ask a trucker about vehicle load and power bands. You will get the same info and speech. Smaller engines produce less heat as there are less cylinders burning around them. My old ’70 ½ ton 8 cyl. 5.7l would get hot on the freeway going up and down hills, while a buddy of mines Toyota 2.2 4cyl. Would run all day in the low temp range. I had more metal to move and heat to remove than he did.

 

[Chaoticbastard]

I agree w/ klutch

The "bad";
Do you live in an area that has a lot of hills, large or small? Drive w/ your AC on pretty much all the time in stop and go traffic?
The "good";
Do you use your vehicle on flat highways? Not much traffic to and from?

I'm thinking that your buddy is talking about "lugging" your engine. The key to understanding this is, understanding "Load". Low RPMs w/ high load is not at all good for the car/truck (any motor or engine). As you spin the engine faster it produces more power and is "stronger" with respect that, the engine can handle the load more efficiently. Your mechanically driven oil pump is RPM dependent; this pressurizes the oil passages around your bearings. The same oil that is the "cushion" around your crankshaft main journals. Your ECM senses the additional load, adds more fuel to compensate. More fuel burns in the combustion chamber, pushing harder against the oil cushion around your crank and will increase "wear". Also this will tax the cooling system. It too is RPM dependant. The less the engine spins, the less coolant flows. This taxes the system. The engine will run hotter, the oil gets thinner = less protection.

Your tranny shifting in and out of O/D is not healthy. This ought to be self-explanatory.

Each vehicle has its own unique design characteristics and flaws. Ask a trucker about vehicle load and power bands. You will get the same info and speech. Smaller engines produce less heat as there are less cylinders burning around them. My old ’70 ½ ton 8 cyl. 5.7l would get hot on the freeway going up and down hills, while a buddy of mines Toyota 2.2 4cyl. Would run all day in the low temp range. I had more metal to move and heat to remove than he did.

That is what I am talking about :yourock:

 

[1wykdmk8]

I am not going to get into the engineering here, but I drove my car with the OD off for YEARS, and still do. I have my switch wired up to the traction control switch and I have the traction control off as well. I live in Pittsburgh now (pretty hilly, and somewhat hot in the summer), and before I lived in NY (the area I lived/worked in I had to go over a few mountains to/from work) and again got pretty hot in the summer. I ALWAYS had my OD off, as a matter of fact I had it wired up so it and the traction control was off when the car started.....opposite of the way the factory has it wired. And I NEVER had a problem with the tranny whatsoever. :shifty:

 

[torquemonkey]

I am not going to get into the engineering here, but I drove my car with the OD off for YEARS, and still do. I have my switch wired up to the traction control switch and I have the traction control off as well. I live in Pittsburgh now (pretty hilly, and somewhat hot in the summer), and before I lived in NY (the area I lived/worked in I had to go over a few mountains to/from work) and again got pretty hot in the summer. I ALWAYS had my OD off, as a matter of fact I had it wired up so it and the traction control was off when the car started.....opposite of the way the factory has it wired. And I NEVER had a problem with the tranny whatsoever. :shifty:

Exactly! OD off in the hills is good. OD off in the heat is good. OD off in low rpm cruizin' is good! OD off when doing 90mph on the freeway is . . . OK! Lowers gas mileage and the high rpms due generate more heat and wear. But does it take 1 mile or 10K miles off the engine? Is maintnenace a factor? Is ambient heat a factor? Sure . . .
Cars/trucks ran all day long, everywhere, all the time before OD and a Locking torqueconverter. So if you chose to go the same route, it won't kill it overnight. Mabey it'll take a few years to do so. Throw in the factors above and we can bench race for years about these issues.
As a quick reference ask a freighter about operating a vehicle at its best for gas mileage and equipment longevity. The trucking industry is a great model for this argument. There is a resaon that the majority of profitable companies out there do what they do. Run at night; cooler, manual trans; keep the "load" in the right gear and power band, etc . . .

 

[Lincolns Own]

well, i've been to Pittsburgh abit (family) and so i understand the hills.

here in missouri, there are hills here and there, mostly where new development is. i hardly ever drive with the air on and its neighborhood and highway roads. since i live right in the city, i dont do alot of "long-distance" highway driving. i get about 16mpg. i've always had OD off and when i thought i heard a knock about a year ago, i took it straight to the dealer. they said the tranny was beautiful, and they put in new fluids.

so i was just seeing if what my friend said was true.

thanks for the info guys