Anyone running 4r70w, 4.56 gears and 35's?

[rjrobin2002]

I am thinking of putting a 4r70w in my Bronco that already has 35's and 4.56 gears. Is this a low enough axle gearing for me to utilize the overdrive?

 

[COBlu77]

It's been a perfect combination for me. If I had a 302, I'd probably want 4.88's, but with 4.56's and a 5.8L, I cruise at around 2200 rpms at 65 mph and my crawl ratio is very close to what it was stock with 3.50's, a C4, and D20. It's very nice to drive around town or out on the open highway. It really doesn't unlock the torque converter or down shift unless it needs to to go up a grade, and always seems to find the right gear for the right speed or grade. A lot of that is in the Baumann controller program. It shifts and behaves almost identically to my newer F150 with a 5.4L and 4R75W.

The fuel mileage has been decent. I've gotten as good as 14-15 on a 65 mph cruise down the highway, but typically it's around 11-12 mpg in city driving with my foot in it and somewhere in between for mountain driving. With the C4 and 4.56's, the best I could do was 11 mpg.

Offroad it's worked well with no temps above 200, but I have a very big tranny cooler. I have towed my camping trailer a few times and I can easily maintain 60 to 65mph up the steepest grades and passes without temp issues either.

 

[WyleCoyote]

I have an AOD with the 4r70W gears in it, 4.56, and 35's, with an Explorer 5.0. It works ok, but I think the 4.88's would be better. The 5.0 just doesn't have enough low end torque for it. I see you have a 347, so you'll probably be ok with the 4.56s

 

[needabronco]

I run an injected 302 with an AOD (same OD), 4.88's and 34" (315/75/16)tires. If I had a 351 it would be the perfect combo on the highway, I'm a hair under torqued at 70 (2200 RPM's) with the 302, at 75 (2500 RPMs) it's much better. I've kicked the idea that 5.13's would better suited for the 302 on the highway. My crawl ratio in 4 low is great so no complaints there. On my last all highway trip that was about 800 miles, I managed one tank of gas (mostly 70) at 14.9 MPG's, the rest (70-75) were in the 12-12.5 MPG range, just to give you an idea.

 

[rjrobin2002]

I am going to be putting a np205 behind it, so I will lose some of the dana 20's low range. It is my street driver, so a super low crawl range is not important. Glad to hear that 4.56 is a good ratio for the overdrive and 35's. My 347 has a cam for lower RPM torque, so that should help also.