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Expected axle gear ratios & what ratios are you hoping for? (dependant on engine & tire choice)

The Pope

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As the title ask, as I felt that this would be a good topic for discussion.......

With the different engines & tire sizes, what are you expecting / wanting for the Axle Ratio?



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As the title ask, as I felt that this would be a good topic for discussion.......

With the different engines & tire sizes, what are you expecting / wanting for the Axle Ratio?
I think it will be similar to Jeep.
Use the Ranger 3.73 for the lower trim “street” options and even light Offroad trim. With the <32” tires

then a 4.0-4.1 for the higher trim option. for anything with a 33”+ tire.

transfer case with that too will likely be the 2.7 on lower trims. HOPING for 3.5-4.0 low for the higher trims
 

JimmyDean

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I really think a 4.11 on something that comes with 37s, or even steeper if it is a full trim package, like 4.55s or so.

3.73s as the most common, maybe on a city 31-32" tire with the 2.3 and A10 something in the 3.3 range. granted all of the a10s I would expect to have a numerically lower rear gear than the sticks.

big question is the T-case, do we get a 4:1?
 

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Lol, who knows what they'll cook up!


For example, Super Dutys, Tremor w 35.1" tire gets a mandatory 4.30 gear and 7.3L or diesel motor.
Lariat pkg with 20" rim uses a 34.3" tire and the base ratio is 3.55 with the same two motors.
That's a large gearing difference in relation to the small tire diameter difference.

Side note :for future reference, know that 35 x 12.5 tires range from 34.5ish to 35 inches.... they are rarely exactly 35" tall.
Same for 33's or 31's, they'll usually measure shorter than stated.
Check the manufacturer specs.
 

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No time to check the calculators right now, but my initial thought is, a 37" tire will need a 4:56 or lower gear for driveability sake .... maybe 488 or 513 even....that's a tall freaking tire.
With over drive trannys, even 33's can use 4.56 gears, definitely 35's....for reference.
 

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It will depend on the gear ratios of the 7 speed manual. I hope that L is around 7.0 and first is about 4.0. I will want the lowest axle ratio offered, my guess 4.30
 

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It will depend on the gear ratios of the 7 speed manual. I hope that L is around 7.0 and first is about 4.0. I will want the lowest axle ratio offered, my guess 4.30
First gear of the manual will likely be around 4.5 (close to the 10speed auto)
With the crawler around 6.5
 

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One of the things that makes my Raptor a pleasure to drive is how eager it is to roll from a stop with the 4.10s. Even at 6,200# 400ft-lb moves it effortlessly.

Considering the weight difference, I'd guess 3.73s with the 2.7L and 4.10s with the 2.3L as minimums, if you can even get 37s with the 2.3L.
 

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BAUS67

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A lot of the jeeps we do are in the 4.88-5.13 range for 35's thru 40's. If it's gas mileage you want then 4.30 or 4.56, IMO the smaller gear makes Jeeps a bit bla to drive when try to giddy up and go, but that's a Jeep. The higher numerically gears are much better for the "peppiness" but boy down the highway they can be screamers. Back in the old days you didn't have the overdrives like today. You had 4.56 or 4.88 in you street car, the highway was off limits, 4K-4500 RPM @ 60 is not bearable for very long. :ROFLMAO::ROFLMAO:
 

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A lot of the jeeps we do are in the 4.88-5.13 range for 35's thru 40's. If it's gas mileage you want then 4.30 or 4.56, IMO the smaller gear makes Jeeps a bit bla to drive when try to giddy up and go, but that's a Jeep. The higher numerically gears are much better for the "peppiness" but boy down the highway they can be screamers. Back in the old days you didn't have the overdrives like today. You had 4.56 or 4.88 in you street car, the highway was off limits, 4K-4500 RPM @ 60 is not bearable for very long. :ROFLMAO::ROFLMAO:
thank god for overdrive. My coworker has a old 58 Chrysler. 3 speed no overdrive. Took it cross country.
Got back and ordered an overdrive kit. >.<
 

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My guess is that Ford will want to meet or beat the stock Jeep Rubicon in every category on their highest off-road trim.

The manual Rubicon has a crawl ratio of 84:1 (5.13 x 4.0 x 4.1) on 33" tires. Rear axle is a Dana M220.

Assuming the same engine torque applied, the 35" tires of the Bronco will reduce the wheel torque compared to the Jeep, so a higher crawl ratio will be needed just to meet the Jeep. 35/33 x 84 = 89:1 crawl ratio just to meet the Jeep in wheel torque.

My estimates are that The crawler gear will be ~6:1. Transfer case 4:1. Rear diff. 4.1:1. for a crawl ratio of 98::1:. Maybe they push it to 100:1 for marketing.

This Bronco must be going for a serious crawl ratio because the rear diff was quite large (Dana M251 axle). This is two steps above the Rubicon diff. Obviously, much of this is from the increased engine torque, but the rest should be from the gearing up tront.


For the base Bronco, I would not doubt they loose the crawler gear to reduce cost of gearbox and differentials because the Getrag MTI550 is available in 6 gears. My guess for the base is a 3.73 rear diff, 2.72 transfer case from F-150, ~4.7 first gear for a crawl ratio of 48:1.. Worse than Jeep base, but Ford wants to push you to higher trims.
 
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JimmyDean

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I'm changing my answer.

the only acceptable axle gear ratio is 6.72. And that is the only acceptable axle as well, the Rockwell 2.5 ton.

because...reasons.
 

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For the base Bronco, I would not doubt they loose the crawler gear to reduce cost of gearbox and differentials because the Getrag MTI550 is available in 6 gears. My guess for the base is a 3.73 rear diff, 2.72 transfer case from F-150, ~4.7 first gear for a crawl ratio of 48:1.. Worse than Jeep base, but Ford wants to push you to higher trims.
I'm guessing they don't offer a 6-speed manual at all.

The take rate is going to be low enough on the manual anyway, there's no good reason to offer 2 different manual transmissions.

If the 7-speed manual is tied to higher trims, I'm guessing lower trims will be 10-speed auto only, no manual option.
 

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So with the new info I used 6.5 crawler first, 2.72 transfer case F-150, and a 4.7 final gear comes in at 83.1 crawl ratio in my calculator. Right in the Rubicon range. (y)(y)
 

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