GEAR Up GRADE
#11
07-26-2005, 12:38 AM
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#12
07-26-2005, 04:15 PM
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#13
07-26-2005, 05:57 PM
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RE: GEAR Up GRADE
ORIGINAL: Silver_Dodge
3.92 gears would not be low enough for that size tire in my opinion. You would not be back to stock at all, that is almost a 34" diameter tire. 4.11 is closer to stock with that size tire.
Also, you won't have to worry about changing differential cases until you get over 4.56.
Your stock suspension should be able to handle those tires, but you will notice a difference in ride quality. Beefing up your suspension is not a bad idea if for no other reason then to help improve the way those tires ride and respond on and off the road.
3.92 gears would not be low enough for that size tire in my opinion. You would not be back to stock at all, that is almost a 34" diameter tire. 4.11 is closer to stock with that size tire.
Also, you won't have to worry about changing differential cases until you get over 4.56.
Your stock suspension should be able to handle those tires, but you will notice a difference in ride quality. Beefing up your suspension is not a bad idea if for no other reason then to help improve the way those tires ride and respond on and off the road.
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Calculating Tire Size
Tire Diameter = (2 x Section Width x Aspect Ratio) / 2540 + wheel diameter
Ex: 245/75/16 tire
Diameter = (2 x 245 x 75) / 2540 + 16 = 30.46850394 -> Rounded to 30.5
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Calculating Gear Upgrade When Changing Tire Size
New Gear Ratio = New Tire Diameter / Old Tire Diameter x Old Gear Ratio = New Gear Ratio
Ex: 32.9 (that's what 305s are) / 30.5 x 3.55 (assumed stock ratio) = 3.829344262 -> Round to 3.82 or 3.83
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And bump that up to 3.92 to compensate for more rotating mass (not to mention it's a more common ratio) and that's how you come up with my answer. Also, there ARE some Dana 44 carriers that require an upgrade when going with a gear set higher than 3.73. I'm not sure if the second gen Ram axle is one of those. That's why I mentioned that it MIGHT need to be changed.
#14
07-26-2005, 07:22 PM
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RE: GEAR Up GRADE
Ahh, I see whats going on. We were using the same formulas, but I was using the tire size he stated at the beginning (305/75/16 which is 34.01"), and you must be using the tire size he mentioned later (305/70/16 which is more like 32.8).
Using my numbers:
34.01/30.5 x 3.55 (assumed stock ratio) = 3.9585409836 -> Round to 3.96, bump that up a little to compesate for rotational drag/aero losses, and then go to the next available gear size above 3.92 = 4.11
That's how I came up with 4.11. Sorry for the confusion.
Using my numbers:
34.01/30.5 x 3.55 (assumed stock ratio) = 3.9585409836 -> Round to 3.96, bump that up a little to compesate for rotational drag/aero losses, and then go to the next available gear size above 3.92 = 4.11
That's how I came up with 4.11. Sorry for the confusion.
#16
07-27-2005, 04:49 PM
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RE: GEAR Up GRADE
ORIGINAL: Silver_Dodge
Ahh, I see whats going on. We were using the same formulas, but I was using the tire size he stated at the beginning (305/75/16 which is 34.01"), and you must be using the tire size he mentioned later (305/70/16 which is more like 32.8).
Using my numbers:
34.01/30.5 x 3.55 (assumed stock ratio) = 3.9585409836 -> Round to 3.96, bump that up a little to compesate for rotational drag/aero losses, and then go to the next available gear size above 3.92 = 4.11
That's how I came up with 4.11. Sorry for the confusion.
Ahh, I see whats going on. We were using the same formulas, but I was using the tire size he stated at the beginning (305/75/16 which is 34.01"), and you must be using the tire size he mentioned later (305/70/16 which is more like 32.8).
Using my numbers:
34.01/30.5 x 3.55 (assumed stock ratio) = 3.9585409836 -> Round to 3.96, bump that up a little to compesate for rotational drag/aero losses, and then go to the next available gear size above 3.92 = 4.11
That's how I came up with 4.11. Sorry for the confusion.
And to answer DEN's post...the gears from your friend's 01 dually wouldn't work in his truck. He has a corporate axle (or possibly dana 44) in the rear while your buddy with the dually is going to have a dana 80. They're not gonna work.
