imafordboi69

Im sure that i could just be out of my mind, but i decided to ask just the same. During the last three day weekend i towed my 26ft camper from Moscow Idaho to Libby Montana. I climbed several grades and got to spend alot of time playing with the O/D off button trying to find the best way to tow. I found that, yes, it is better to tow with the O/D off but it got me thinking. In most vehicles when you turn it off, it seems to just eliminate the highest gear to avoid the constant shift on slight hills. After turning off the engine it reverts back to having the O/D on and i would sometimes forget to switch it back off. What i noticed was that at any speed and in any gear when i would push the button it would always seem to shift down. I also noticed that with it switched off, i also had better acceleration capabilities from a dead stop. It got me thinking that perhaps it wasn't just eliminating the highest gear, but was in fact maybe splitting the gears or changing something inside the transmission or transfer case to output the same gears but at an altered ratio? It seems possible to me and sounds like an awesome feature if this is the way its working, but i could also just be crazy.

lsucrf250

it just does not allow your trans to shift into overdrive, which you are suupose to use when towing. Its the same thing as GM's tow-haul mode. So with off your torque converter will be fully locked in third instead of locking in fourth/over drive.

60DRB

Hmmm, Now that I think about it, I have noticed the "forced" downshift you mention, even if I'm in 3rd already. There probably are things the electronic controlled xmsn can/does do that we aren't aware of. Some things the tuners take advantage of, in addition to tlking to the engine controlers.

techrep

iTrader: (1)

Unless your in 4 wheel drive your transfer case has nothing to do with the overdrive function.

lsucrf250

if you have an edge programmer you can set the screen to show you what gear you are in and if the torque converter is locked or not. U can def notice how much it will shift in and out if you are towing. Overdrive is just a higher gear ratio to reduce rpms of the motor and therefore more mpgs. When towing it can be harmful to your trans to stay in overdrive.

kozal01

iTrader: (2)

its not being in overdrive that ruins the trans its the constant shifting between 3rd and 4th/ OD that overheats the trans therefor destroying it. when i tow if i notice it hunting for gears alot while at cruising speed i will lock out the OD but if it can get into OD and stay there then i usually leave it on.

lsucrf250

ya that is true but i just like being on the safe side because trans problems can be very expensive!!!

kozal01

iTrader: (2)

i dont disagree with that. the reason i do it is because i have an edge tuner so im able to watch my trans temp and i also know what gear im in so ill know before something happens to it. before i had the edge i just shut off OD no matter what.

RoushNitemare

i turn off O/D when i wanna have a little fun cuz i can definitly feel it accelerates much quicker when O/D is off

imafordboi69

OK so im not the only person who notices the better acceleration when its turned off. Why would the truck have better acceleration if all your doing is eliminating the highest gear? I mean i notice a big difference when im towing between having it on and having it off. there must be something else going on here.