Like the title says, I'm looking for someone who has re-geared their truck with the 6 speed in it. I took a trip this past week and it seems the 6 speed did quite a bit of downshifting. My new truck seemed to shift more than my 2003 with 35's did on it. I'm not sure if it is normal for the 6 speed to shift quicker or not.

I'm also thinking about re-gearing my truck to improve the mileage some after the trip this past week. I actually got a little better mileage on the trip by running the truck in tow/haul mode. The trip was 320+ miles one way and I got it up to 14.1 mpg according to the info center. It calculated out to 13.2 mpg for the tank, including some towing around town moving my son.

I know the lift and tires will cost me mpg, just curious what I can gain back by going from my 3:73's to a new gear. Most people said that 4:56's were the preferred gear for the 97 - 08 trucks, curious on what the thoughts are on the 2009/2010's.

 

Wouldnt a higher ratio gear give you lower MPG? Also 6 speeds are designed to change up and down a lot. A lot more so than a 4 speed. Esp between 5th and 6th. The reason is so that you get better MPG. Try and drive a 7 speed and you will think the Ford six speed hardly changes at all.

 

Didnt you use a programmer with your truck? I would think that would help a bit - but maybe not. Im getting the hypertech regardless so I can correct my speedo and was hoping the different tune would improve gas mileage.

 

You need to reprogram for Gears with the 6 speed. Went down this road with a 6 speed allison and duramax (much more torque then the 5.4) and had shift issues. Set it up for the proper tire size in the computer and things were back to normal.

If it were my truck I would not regear. I'd tune it right and if I was still hunting a bit get a good exhaust and intake and let it ride. Your 6 speed is actually equal to a 4 speed with 4.56 gears as it sits, might even be deeper with the 6 speed. I never reprogrammed my 03 for 35s and it sucked. I did my 06 silverado and made a huge difference in shifts and driveability, I also reprogrammed my wifes car for her tires and made a difference. I'm betting that you'll see a major difference with the correct tire size programmed in.

You will see more hunting with the 6 speed then the 4 it's the nature of the beast. The biggest mistake ford made in my opinion was not being able to select 6, 5, 4, 3, 2, 1 manually like GM, Toyota, Allison, and Cat have done.

 

How do you figure that? THe 6 speed has a slightly deeper over drive (0.69 vs 0.70) so its like having less gear. a 6 speed will turn less rpms than a 4 speed. That being said you will need to give it more gear. If you are talking about 1st gear then yes the 6 speed is like having 4.56 gear since the 1st gear is so low but that doesn't play into his gas mileage nearly as much.
In stock form the 6 speed gets better MPGs than a 4 speed because it shifts more than the 4 speed and thus can keep the engines rpms down as you accelerate. The highway mileage is better too because of the slightly deeper overdrive.

All that being said 4.10s would bring you back to stock rpms. Personally I'd go with 4.56s. You will be turning about 10% more rpms than stock on the highway but on the street you will get quicker acceleration without having to dig into the throttle. The extra gearing will also help with the extra weight of the tires. You will take a lot of stress off your transmission and it should be able to hold 6th gear on inclines.

 

4wDakota,

Will he get better mpgs? If so, do you think he will get back to "stock" mpgs?

 

Not with that much additional rotating mass.

 

Sorry dont know how to use the Quote thing

Yetti96
Even if he does a tuner and gears? My drive to work is about 20 miles each way with stop and go traffic. Is there a big difference in 20s with 35s and 22s and 37s?

 

Overall the 6 speed is better, I've only rode in one 2010 w/ 35s and it felt much better then several peoples old F-150s w/ 35s and 4.10s or 4.56s (mine with 3.55s sucked). The 6 speed didn't lug as much as noted in your statement about keeping the RPMs in a usable range.

I still stick with a good tune first. A good tune is less then 500 (maybe 400), gears, if done with good parts are going to be an easy 1500 if he can't install them himself. He'll need the tune if he does gears anyway so might as well try the tune first.


As to 37s, I personally would not run them on a IFS truck unless it's going to be a pavement queen. That's my .02 cents, in the construction business I've seen a lot of guys run 37s on their F-150s and have many more issues then a SFA truck w/ 37s. I'd run 35s personally. It takes a lot more engine to move them and a lot more brakes to stop a 37, it's more stress on the wheel bearings, control arms, bushings etc. I'd venture to say each tire will weight at least 30 lbs more (35 vs 37 depending on brands and tread compound), that's HUGE in terms of rotational mass. Do you plan on towing with 37s as well?

 

You will never get back to stock but having it geared right will improve mpg.

If you do a lot of highway cruisin on flat ground go 4.10s to keep the rpms down. If you do a lot of city or hilly areas go 4.56s.

 

MonteCarlo31,

I will only be hauling my two quads. I love to look of 22s with 37s but Im very concerned with the life spand of my motor and tranny.

 

I have a Hypertech programmer and have the truck programmed for the 35's. I am using the power tune on the programmer and I don't feel short of power. I would however like to have a little less shifting and better mileage.

I may try it back on the stock power settings and see what the mileage does there. I realize there are better tunes available, but not many options for the 09's yet. Any other thoughts on the topic?

 

check your PM's.

 

You guys think it's worth it to reprogram for just 33's and 3.55's?

 

I went ahead and highlighted the problem. Hypertech in anything I've seen has sucked. They are very conservative on their tunes and don't give a lot of room for adjustments. I'd bet you'd see much better results with a SCT tune especially since you can do custom tunes.