Stumpknocker27

I've read several folks who say they put bigger tires on their trucks and now the tranny hunts for gears when they tow or go up an overpass. Would it hurt anything to lockout 6th gear and keep the truck in 5th to get a little lower gearing? Essentially it would be doing the same thing as having a lower gear in the rear right?

Mattm400

It wouldn't hurt a thing but your MPG's.

Stumpknocker27

Not really concerned about that, I was just wondering about overheating/screwing something up. I used to do it all the time with my old Chevy 4.3 4 spd when towing a heavy trailer. It seems that 5th and 6th gears in our trucks are geared very high, almost too high in 6th.

brucesears

Both 5th and 6th gears are overdrive gears, it wouldn't hurt anything.

2012platinum

I have 35's on my truck, 3.55 rear, with the ecoboost.. I have had no problems towing anything I wanted. Including a friends 28ft FEMA camper for him. Jumped on interstate and ran 75-80, no problems. Of course when going up a hill it would downshift, but what half ton truck wouldn't? I did have the tow/haul button pushed, and it stayed in 6th gear most of the time

vozaday

When I tow I lock out 6th gear, I tested it out one day and on flat ground at 100km/h the difference between 6th and 5th was basically 1 mpg (that was with 8000lbs behind the truck). Never tried it without a trailer but I may try it next week. And like 2012platinum said, mine doesn't hunt at all with my 33's.

Stumpknocker27

I have the 5.0 and 3.55s, stock tires. My truck will come out of 6th going up a bridge or overpass without towing, even more so when towing (18 foot boat). I want to put 34" bfgs on my truck when the stockers wear out so I'm sure that'll increase the load on the drivetrain and it'll come out of gear even easier. That's what got me thinking about looking out the upper gear in the first place. It's nothing excessive, but coming from a tuned 5.6l titan with a lower axle ratio I find it comes out of gear a lot. I will eventually tune my 5.0 but I think I'll wait until my extended warranty goes out.

2012platinum

I've heard of a few 5.0 owners say the same thing. The ecoboost makes a lot of torque at a relatively low rpm. Without a trailer, mine never drops down unless I'm pushing it or trying to pass. I think a tune will def help you though. It made a huge difference on mine.

RES4CUE

I use the tow/haul mode. It basically holds gears longer and you don't have to lock out.

DirtMcgirt

If I'm towing on anything besides a flat road I lock out 6th. In small rolling hills I seem to get better fuel economy in 5th.