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I just bought a mint 98 4.6 scab with a 3:55 8.8 rear end and was thinking of installing 4:10 gears.Anyone have 4:10s and whats the rpm at 65 for this truck?Also the dealer says ford doesn't make a 4:10 gear which is strange since i can get them from ford racing myself?Am i missing something or was it just an uninformed lazy a$$ at the parts counter?
yea you can get 4.10's from ford racing, ford racing and ford are not the same outfit though, so dont talk to ford about it. i have an 02 mustang aswell with the 8.8 and there all the same. im going from 3.27's to 4.10's. once spring comes.
Theres a formula to figure out your new rpm's with your new gears. this is what i think it is, im not quite sure anymore but when i do it it seems right.
rpm's x new gears divided by old gears.
Example, lets say you drive 1900rpm at 60mph. and your stock gears are 3.55's and your going to 4.10's.
1900 x 4.10 = 7790
7790/3.55 = 2194 rpm's
now this only works if you keep your same tire size as you had on your previous gears. For installation, ffrp is the best, stay with ford racing gears. get a new crush sleave, pinion seal, and some friction modifyer. you may or may not need new shims. from what i have heard on mustang forums that ford racing is easier to install for the mechanic or you. they say they pretty much just you the original shims.
oh yea and to recalibrate your speedo, i think you can use one of these for a f150 too. you might have to call them. or if you have a hand held tuner you can use that.