Overdrive Switch?

capnjim · 09-30-2010, 09:26 AM

Is there a way to build a switch to disable the overdrive on a late model Ford transmission equipped with a 5spd automatic and the tow haul feature. With this style transmission the overdrive can't be deactivated. My unit has a 5.4 with 4.11 gears and 235 85/16 tires. I'm pushing a lot of weight (11,500 lbs) an would like to get the truck out of overdrive to keep the rpms up a little bit more. At higher RPM's it seems to need less throtle to maintain the same speed. Ideas?

Jim Grant
2006 E350 Superduty DRW Quigley 4x4RV
5.4 Triton

carringb · 09-30-2010, 11:50 AM

Yes, but it requires custom programming, or installing a standalone transmission controller. You can also use a programmer (like Predator) to change shifts points.

Your issue is rear end gears. The E350 comes with 4.1 gears standard, while the E450 comes with 4.56. The taller tires make the 4.10 gears even worse.

4.10 gears just aren't low enough. I even put 4.56s into my E350 van.

capnjim · 09-30-2010, 12:52 PM

Thanks for the reply. Two questions, where would I find a stand alone transmission controller for my e350 and how much did it cost to swap the 4.11 to 4.56 gears. Oh, and what type of shop can do this work?

Jim

carringb · 09-30-2010, 04:56 PM

Most Ford dealers and Independent axle and 4x4 shops can do the gear swap. You do need to have the ECU reprogrammed, which can only be done at a dealer (as far as I know).

The gear swap should run about $750-$900 depending on your local labor rates, and then reprogramming the ECU is 30 minutes labor.

While you are at it, you may want to to consider an ARB air locker or and electric locker for your rig, considering it's weight and where you may be taking. Not cheap, but having 2 open diffs means you really only have 2wd still (one on each axle) and Limited slip can be good (other than Ford, which doesn't have enough pre-load) but I've discovered that with my heavy setup, I'm seeing much more clutch wear than I expected. Enough so that I have to periodically clean my differential speed sensor because it collects the clutch material. My van is around 8000 pounds on the rear axle when loaded, which I imagine is similar to your rig.

You can get a Powertrain Control Solutions standalone controller from http://destroked.com/. But I think you may lose some other features (like Tow/Haul mode).

I strongly suggest the gear swap before doing anything else. With the 4.56 gears I rarely turn OD off, except for braking, which your Tow/Haul mode does for you. BTW - you should probably drive with Tow/Haul most of the time. It will reduce hunting.

There is a product for the E-series which will default to Tow/Haul mode:
http://www.intermotive.net/Brochures...Controller.pdf

capnjim · 10-01-2010, 10:53 AM

Thank you again for the responses. I'm going to start with the 4:10 to 4:56 gear swap. I wasn't thinking obviously I need to do both axles. I'm sure this is going to give me more power. Did your gas mileage suffer when you made the change? My mileage is brutal, about 8mpg, I hoping that it will get better if the engine isn't lugging. Right now with the overdrive on so much I have to add a lot of throtle to keep rolling. At 55mph it's reving at maybe 1800 or so. A little higher RPM the engine seems to make a lot more power. I rarely exceed 65 so I'm not too worried about the 4:56 gear change. I would like to do the controller as well but the list is long.

Jim

carringb · 10-01-2010, 11:47 PM

My solo gas mileage went down, but my towing gas mileage went up, and when I'm towing I think that's more similar to your rig. Now.... at 8 MPG... that's pretty on par with more motohomes it seams.