I have a 2001 f-150 with 33" tires. 3.55 stock gears. my accelration suffered a bit with new tires, but my question is, when i take off the overdrive button, my truck drives like it was stock. my rpms go up, but driving with it off will it affect my engine in any way in the long run? what about driving with it on with so LOW rpms is that bad too? thanks guys

 

I think your engine should be fine. The only thing that will suffer a bit is you mileage if you leave your OD off at freeway speeds. I recommend that you shift into overdrive once you reach a "cruising" speed. Although, eventually, if you have the funds, go with a more appropriate gears ratio to offset your larger tires. You might also want to have your speedometer recalibrated.

I wasn't aware, but does the tranny shift differently if the OD is off???

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F-150 SuperCab XLT 4X4
Black w/Gray Two Tone
5.4L Triton
Class III Towing
3.55 LS
BFG's 285/75/16R
6 CD Changer
Captain's chair
Lund Deflector Shield

 

The tranny shifts the same either way. I wouldn't worry about O/D being off. You might even prolong the life of the tranny some since it's not always going 4th-3rd-4th-3rd repeat.

Low RPM's and high loads are bad becaused the bearing are put under alot of stress with out the benefit of a lot of oil flow like you'd have at high RPM's and high loads.