transmission / gears / tires

[farmerjohn]

Hey Guys , I am trying to decide whether to swap out my C4 for a 4R70W or AOD. I have a 351 W that is built fairly well with Fuel Injection, and plan to run 39" tires w 5:38 gears in some '06 Super Duty axles. So my question, does anyone have experience w this set -up / gear ratio/tires ? I want to be able to run 75+ on the Interstate. I have an Atlas w 3.8s for the slow stuff.
Thanks
Planning to start hanging link brackets and only want to do it Once !!!

 

[sykanr0ng]

Take into account that Ford automatic overdrive transmissions have very high OD ratios; 0.67 for the AODE and 0.70 for the 4R70W.

Will this make your engine RPM in overdrive too low to produce enough torque to push an un-aerodynamic Bronco down the highway?


http://classicbroncos.com/tech/aode-4r70w-3-speed-automatic-transmission-guide

 

[Apogee]

Your combination should run pretty decent I would think.

You'd be at 2433 RPM in OD with 39's and 5.38 gears, which your EFI 351W will love. You could probably get away with 5.13 (2320 RPM) or 4.88 (2207 RPM) gears as well, essentially moving your shift points up a bit. I'd go wtih the 4R70W and a controller, as that will give you some added control with respect to shift points, downshifting, etc.

My setup will be similar, except I'm installing an NV4500 with 4.88 gears and 37's, so a bit different. I would have done 4R70W with a controller, but I already had the NV4500 from a past truck, so I figured I'd use it.

 

[farmerjohn]

Your combination should run pretty decent I would think.

You'd be at 2433 RPM in OD with 39's and 5.38 gears, which your EFI 351W will love. You could probably get away with 5.13 (2320 RPM) or 4.88 (2207 RPM) gears as well, essentially moving your shift points up a bit. I'd go wtih the 4R70W and a controller, as that will give you some added control with respect to shift points, downshifting, etc.

My setup will be similar, except I'm installing an NV4500 with 4.88 gears and 37's, so a bit different. I would have done 4R70W with a controller, but I already had the NV4500 from a past truck, so I figured I'd use it.

Thanks for the input! Using those numbers, it would be screaming without the overdrive.

 

[edones06]

Thanks for the input! Using those numbers, it would be screaming without the overdrive.

O yea. I run 5:38 and 37's with a c6. And yes my ol 5.0 is singing a song on the road. But it gets very little street time. I would thank you would be fine with over drive

 

[Apogee]

Thanks for the input! Using those numbers, it would be screaming without the overdrive.

Sure, no problem. There are some really good online calculators that are helpful when trying to figure out what you want to do with respect to transmissions, axle gears and tire size. To get the numbers in my previous post, I used the Grimm Jeeper site: http://www.grimmjeeper.com/gears.html