i was wondering if someone could clear up a question i have about gears. now i know that gears can give your car better gas mileage and better launches and so forth, but what are the differnces in sizes??? i.e. 3.55, 3.73, 4.10, 4.30's etc etc.... what does each size do for you?? if anyone could clear this up, i would greatly apreciate it. thanks.

 

it i not a size, it is a ratio. 3.73s would mean that the driveshaft would rotate 3.73 times for every time the wheels complete 1 revolution. btw they will not increase fuel economy, unless you go to a lower gear which would decrease acceleration

 

the number is a ration of the ring gear divided buy the pinion gear. the ring gear is connected to the axles and teh pinion gear is connected to the drive shaft. so if you have 3.55 gears in your car your drive shaft will turn 3.55 times for ever time your wheels turns. the bigger the number the more times the drive shaft turns to make the wheel turn. it lets the engine turn over the wheels easier. letting you take advantage of teh hp instead of the torque that the engine creates. i think i probably just confused you even more.

 

Click on this link. www.mustangforums.com/m_600073/tm.htm

 

the ez way to look at is like a lever.....

the longer lever you have , the easier to lift an object , but the less you will move it.

so a large gear (smaller numerically) like 2.73 will move the car at a lowe rpm, but provide less "grunt"
the smaller gear (higher numerically) like a 4.10 will pull a tree stump , and yank tires, but at the loss of top end speed. rpm's will be more at any given point (compared to the 2.73) by about 1000 rpms

it just depends how much "out of the hole" power you want directly compared to how much top end mph you are willing to give up for it.

now different setups require or at least benefit more from a certain gear....blowe rcars for example, benefit by a mid-range gear like 3.55's since they have such a broad powerband. NA cars , typically run better int he 1/4 w/ the largest gear you are willing run. 4.10's are perfect IMO.

tach about 3000 @ 75 mph in 5th gear

 

ANYONE TELL ME WHERE THE AOD'S TACH AT 70MPH W/4.10'S?

 

probably about 2800 or so

they will tach the same as a t5 in 5th if your in od

 

at 70 its gonna be higher then 2800, my 3.73's are at 2800 or higher at 70 in 5th if i remember correctly but dont hold me to it i guess i never really payed attention