Gearing
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Gearing
While I have my front axle apart, I'm thinking I should to a complete rebuild, change gearing and add an ARB Air locker.
I was watching a video on gearing today. Using their formula, new tire size (37") times current gears (3.55) = 13.35 divided by old tire size (32") = 4.10.
Does this sound right? I am going from stock tires 235's to 37's. I have a few modest mods planned to get me to 400 HP and 600 foot pounds of torque.
I was watching a video on gearing today. Using their formula, new tire size (37") times current gears (3.55) = 13.35 divided by old tire size (32") = 4.10.
Does this sound right? I am going from stock tires 235's to 37's. I have a few modest mods planned to get me to 400 HP and 600 foot pounds of torque.
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I want to maintain what I have. It has reasonable fuel mileage, power and tows well.
Hotshot
Joined: Dec 2005
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From: evansville in
If you aren't towing real heavy the 4.10 will get you then but more gear may be better really.
I know my 3.55s and 285 don't get 10k + moving from a stop great without torturing the converter..
I know my 3.55s and 285 don't get 10k + moving from a stop great without torturing the converter..
Cargo Master
Joined: Nov 2010
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While I have my front axle apart, I'm thinking I should to a complete rebuild, change gearing and add an ARB Air locker.
I was watching a video on gearing today. Using their formula, new tire size (37") times current gears (3.55) = 13.35 divided by old tire size (32") = 4.10.
Does this sound right? I am going from stock tires 235's to 37's. I have a few modest mods planned to get me to 400 HP and 600 foot pounds of torque.
I was watching a video on gearing today. Using their formula, new tire size (37") times current gears (3.55) = 13.35 divided by old tire size (32") = 4.10.
Does this sound right? I am going from stock tires 235's to 37's. I have a few modest mods planned to get me to 400 HP and 600 foot pounds of torque.
The 2000 and up axles actually came with a 4.30 option. If I were you running 37s and towing i would not go with anything longer than a 4.30 ratio. A lot of trucks we have built have said this is nearly perfect. Some have gone as high as 4.56s. I can tell you personally that if I were to tow with 37s and 4.10s it would not be the best experience.... 37s on 3.55s... yeah forget it, unless you are hauling around a light camper trailer without the need for overdrive...
Also if you have a 400ho motor your more than likely up in the 900 ft/lbs of torque. You will fine out it will be very hard to keep a 7.3 cool yanking a trailer around at a 400hp setting with 37s under it. We just finished a build doing just that and it was not cheap!
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Joined: Dec 2014
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For final drive ratio comparisons on your tranny if you actually math out a 3.55 or a use a 3.73 base ratio you come to a 4.36s.
The 2000 and up axles actually came with a 4.30 option. If I were you running 37s and towing i would not go with anything longer than a 4.30 ratio. A lot of trucks we have built have said this is nearly perfect. Some have gone as high as 4.56s. I can tell you personally that if I were to tow with 37s and 4.10s it would not be the best experience.... 37s on 3.55s... yeah forget it, unless you are hauling around a light camper trailer without the need for overdrive...
Also if you have a 400ho motor your more than likely up in the 900 ft/lbs of torque. You will fine out it will be very hard to keep a 7.3 cool yanking a trailer around at a 400hp setting with 37s under it. We just finished a build doing just that and it was not cheap!
The 2000 and up axles actually came with a 4.30 option. If I were you running 37s and towing i would not go with anything longer than a 4.30 ratio. A lot of trucks we have built have said this is nearly perfect. Some have gone as high as 4.56s. I can tell you personally that if I were to tow with 37s and 4.10s it would not be the best experience.... 37s on 3.55s... yeah forget it, unless you are hauling around a light camper trailer without the need for overdrive...
Also if you have a 400ho motor your more than likely up in the 900 ft/lbs of torque. You will fine out it will be very hard to keep a 7.3 cool yanking a trailer around at a 400hp setting with 37s under it. We just finished a build doing just that and it was not cheap!
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Post Fiend
Joined: Dec 2009
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From: Livoina,La
If you do the math with 325/80/16 on 3.55 then
Effective gear ratio would be 2.91
New gear needed comes to 4.33
Effective gear ratio would be 2.91
New gear needed comes to 4.33
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Cargo Master
Joined: Nov 2010
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Well I'd get a set of 4.30s if I were you and call it a day...
Senior User
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My f150 is 4wd can't get 4.30 for the front last I checked it's got 4.56's in it for a couple years now no complaints with that gear setup
Edit: now I realize you were probably talking to the op lol
Edit: now I realize you were probably talking to the op lol
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