Gears
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Gears
Originally posted by buckeyebronco
Could somebody explain gearing in the rear end for me. I'm lost when poeple keep saying 4.11 and 3.08 rear ends. How do I know what my truck has in it?
Could somebody explain gearing in the rear end for me. I'm lost when poeple keep saying 4.11 and 3.08 rear ends. How do I know what my truck has in it?
Rich
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From: MA
Gears
What size tires are you running? What do you do with your bronco? All highway miles? Tow? Personally, I like to have a low end grunt more than a highway runner. Plus, selecting the proper gearing can make your around town mpg possibly increase because your motor will not have to search to find the correct rpm by up and downshifting.
Rich
Rich
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From: Gateway to the West
Gears
rpm = mph x gear ratio x 336 / tire diameter
This is the formula for calculating gear ratios based on tire size. The idea with this formula is to keep the engine spinning at or near its power band...(most productive rpm range). If you have a transmission with an overdrive gear, you can factor in the overdrive ratio as well...
rpm = mpg x gear ratio x overdrive ratio x 336 / tire diameter
By way of example:
2349 = 65 x 3.55 x 336 / 33 <----not so bad!
2720 = 65 x 4.11 x 336 / 33 <----gettin' a little wound up!
1762 = 65 x 3.55 x .75 x 336 / 33 <----ouch! low! (trust me this is where I am right now)
2040 = 65 x 4.11 x .75 x 336 / 33 <----now thats better!
This is where having overdrive can be helpful because you can gear up without sacrificing as much power and MPG. With the OD setup you could even go up again and still be under the rpm you'd be turning without the OD.
This is the formula for calculating gear ratios based on tire size. The idea with this formula is to keep the engine spinning at or near its power band...(most productive rpm range). If you have a transmission with an overdrive gear, you can factor in the overdrive ratio as well...
rpm = mpg x gear ratio x overdrive ratio x 336 / tire diameter
By way of example:
2349 = 65 x 3.55 x 336 / 33 <----not so bad!
2720 = 65 x 4.11 x 336 / 33 <----gettin' a little wound up!
1762 = 65 x 3.55 x .75 x 336 / 33 <----ouch! low! (trust me this is where I am right now)
2040 = 65 x 4.11 x .75 x 336 / 33 <----now thats better!
This is where having overdrive can be helpful because you can gear up without sacrificing as much power and MPG. With the OD setup you could even go up again and still be under the rpm you'd be turning without the OD.
Last edited by greystreak92; May 14, 2003 at 06:40 PM.
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