Gears??
09-17-2008, 09:58 PM
#11
Good Lord.....
Join Date: Jul 2008
Location: Mesa, Az
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heres a little equation to help determine what gears for bigger tires...
new tire diameter X current gear ratio = ratio needed to duplicate stock
old tire diameter
for example, i went to 35's from my stock 29's, a 1.2068..... percent change, multiplied by my stock gear ratio of 3.55 gave me a number of 4.2844.....
since there is no such gear as a 4.28, so the options are 4.10 and 4.56. Having an overdrive trans, and occaisonally towing, i opted to go down (numerically up) to a 4.56. This put me at about 100-200 rpm's higher than stock while travelling 70 mph in overdrive, which in my opinion ain't bad. I'm pretty sure they do make a 4.88 for the IFS 8.8, i can't remeber which company it is though, but you wouldn't need that unless you had like 38's or bigger, which is too big for that axle anyways.
new tire diameter X current gear ratio = ratio needed to duplicate stock
old tire diameter
for example, i went to 35's from my stock 29's, a 1.2068..... percent change, multiplied by my stock gear ratio of 3.55 gave me a number of 4.2844.....
since there is no such gear as a 4.28, so the options are 4.10 and 4.56. Having an overdrive trans, and occaisonally towing, i opted to go down (numerically up) to a 4.56. This put me at about 100-200 rpm's higher than stock while travelling 70 mph in overdrive, which in my opinion ain't bad. I'm pretty sure they do make a 4.88 for the IFS 8.8, i can't remeber which company it is though, but you wouldn't need that unless you had like 38's or bigger, which is too big for that axle anyways.
09-21-2008, 10:30 PM
#12
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Join Date: Sep 2008
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heres a little equation to help determine what gears for bigger tires...
new tire diameter X current gear ratio = ratio needed to duplicate stock
old tire diameter
for example, i went to 35's from my stock 29's, a 1.2068..... percent change, multiplied by my stock gear ratio of 3.55 gave me a number of 4.2844.....
since there is no such gear as a 4.28, so the options are 4.10 and 4.56. Having an overdrive trans, and occaisonally towing, i opted to go down (numerically up) to a 4.56. This put me at about 100-200 rpm's higher than stock while travelling 70 mph in overdrive, which in my opinion ain't bad. I'm pretty sure they do make a 4.88 for the IFS 8.8, i can't remeber which company it is though, but you wouldn't need that unless you had like 38's or bigger, which is too big for that axle anyways.
new tire diameter X current gear ratio = ratio needed to duplicate stock
old tire diameter
for example, i went to 35's from my stock 29's, a 1.2068..... percent change, multiplied by my stock gear ratio of 3.55 gave me a number of 4.2844.....
since there is no such gear as a 4.28, so the options are 4.10 and 4.56. Having an overdrive trans, and occaisonally towing, i opted to go down (numerically up) to a 4.56. This put me at about 100-200 rpm's higher than stock while travelling 70 mph in overdrive, which in my opinion ain't bad. I'm pretty sure they do make a 4.88 for the IFS 8.8, i can't remeber which company it is though, but you wouldn't need that unless you had like 38's or bigger, which is too big for that axle anyways.
haha
