Truck Buyers Beware

[Dave R]

Originally Posted by Rattlesnake Guy

Question for the experts. We have two Ford Expeditions with tow packages. Can someone explain what the overdrive on off function actually does? I know it is supposed to be off when towing and on when driving but does it do more than prevent me from going into the highest gear on the highway? If I am pulling the boat up the launch ramp at 1 mph, does it matter if the switch is on or off?

It makes no diffference at low speeds and simply locks out overdrive like you think it does.

I was told by a friend that used to own a transmission shop to use the "O/D off" function whenever driving below 50 MPH or when towing. He also said when towing to ALWAYS shift (up or down) on a lifted throttle. This means that if I'm about to climb a hill that I'm reasonably sure will require 2nd gear at some point, I should manually downshift to 2nd before I start the climb. I have followed his advice and it has proven to be great. My 11 year-old Durango has 120,000+ miles with lots of heavy (7400 lbs) towing on the original transmission with no issues. Dodge transmissions have a pretty bad reputation for short lives.

It might seem kinda brutal to drop into 2nd gear and rev to 4000 RPM to maintain highway speeds up long hills, but it does not hurt the engine at all. It's not any different than the loads a boat engine sees.

[NoBozo]

My current '07 Toyota Tacoma V-6 4x4 (245hp) Access Cab (5 spd) Automatic requires me to be in D4...NOT OD when I TOW. I have a 3,000# trailer/boat. I get 21 MPG on the highway w/o the boat. With the boat I get about 16 MPG in D4. My rear end ratio is 3.73. It is adequate..

My OLD (142,000 miles) 1995 Tacoma V-6 4x4 (190HP) Access Cab STICK (5 Spd) got 27 MPG on the highway W/O the boat and 21 MPG WITH the boat.... going over the mountains from the LR to Rutland, Vt to Lake George.

My new truck is nice because it has all the STUFF that the old truck didn't have..A/C..power windows..etc.

BUT..the old truck was a real working truck...the new one is ...well.. comfortable. NB

[Seeker]

My '04 Avalanche Z71 4x4 w/ tow pkg says to use the Tow/Haul switch and I think it says to drop down 1 gear. Hey, I read the manual 5 years ago. I can't even feel my 12'x101" snowmo trailer w/ 2 4-stroke 2-ups behind me but i sure know when I have a 2,999# boat and trailer behind me. Feels like I'm towing my tractor without a trailer. I don't tow more than a few hundred miles a year so fuel economy isn't an issue.

[Lakepilot]

Originally Posted by Dave R

It makes no diffference at low speeds and simply locks out overdrive like you think it does.

I was told by a friend that used to own a transmission shop to use the "O/D off" function whenever driving below 50 MPH or when towing. He also said when towing to ALWAYS shift (up or down) on a lifted throttle. This means that if I'm about to climb a hill that I'm reasonably sure will require 2nd gear at some point, I should manually downshift to 2nd before I start the climb. I have followed his advice and it has proven to be great. My 11 year-old Durango has 120,000+ miles with lots of heavy (7400 lbs) towing on the original transmission with no issues. Dodge transmissions have a pretty bad reputation for short lives.

It might seem kinda brutal to drop into 2nd gear and rev to 4000 RPM to maintain highway speeds up long hills, but it does not hurt the engine at all. It's not any different than the loads a boat engine sees.

I agree with everything you said. It's the shifting of the tranny at speed that heats it up. If you had a temp gauge on monitoring tranny temp. you'd see a big drop with it in one gear, even loaded, versus constantly shifting. Lot's of rvers have temp. gauges. Cheap way to extend the life of the tranny,

[lawn psycho]

Originally Posted by Lakepilot

Lot's of rvers have temp. gauges. Cheap way to extend the life of the tranny,

I think they are being added standard on a lot of trucks now. I know the F-150s have them although there could be certain models that don't but I think it's standard equipment.

[Coolbreeze]

I think this forum site needs a new topic area. Maybe we'll call it "hot rod shop" or "tech talk" where we can discuss topics like this. I think it will be a huge hit!
The information listed is really useful. Great New Year to all!
-Coolbreeze