Nickdotcom

I don't know anything about gears and i'm probly make myself sound retarded but what is the real differences between a 4.10 and 3.73 gear ratio? I'm just wondering because people feel strongly for each but i don't know why.

JC74

Don't feel retarded it's a good question. This topic has been covered quite a bit, but I give you a quick overview of my understanding. I recommend doing a forum search for other opinions also because I may be taliking out of my a$$.

First do you have a manual or auto tran? The auto will lose power through the powertrain so 4.10 would give you the gain you may want. The 3.73 is what I would use for the manual.

The main diff with gear ratios is how fast off the line you'll be. Easy analogy if you ever ridden a bicycle that had gears. The higher the gear (3.27) the more revolutions you had to pedal to get moving. Yeah, it was easier to pedal but damn you had to pedal twice as much. The exact opposite with a big sprocket less teeth (4.10); takes more power to start pedaling, but you got going faster.

Of course with the the gear change you will higher RPMs. So keep this in mind if you will be doing a lot of road trips. I hear people say you will notice a 2-3 mpg decrease with the increase. Couldn't tell you from exp. still waiting on mine. I am gonna go with the 4.10 Auto trans.

Here is the formula for calculating RPMs. There are also RPM/Ratio calculators online that will do the math for ya.

RPM = MPH X Trans Ratio (in high gear) X Rear End Ratio X 336
Tire Height

sicride

Common and small mistake there in your language I think you just confused them but have a good understanding of the concept here. The 4.10 gears will be a bigger gear with more teeth and will be easier to turn. You will accelerate quicker with a higher ratio rear end gear but will be sacraficing top speed (supposing you could reach redline in top gear). 4.10 is more of a drag rear end gear 3.73 will get you better acceleration than the 3.32's or whatever are in it stock and better gas mileage than a 4.10 and if you are worried about top speed you will have a better top speed with a 3.73 most likely. I personally am big on drag racing and acceleration not top speed and would go with the 4.10 unless you are adding a supercharger.

Maybe others can give you more information along the lines of what you are looking for if JC74 or I did not hit on that.

Redfire

Yeah, but it all boils down to what the individual is goin to do with the car. For example, drive it to work many miles on the freeway,=3.55s like the GT five speeds come with, or drag race it,= 4.10s on down. The boring relationship of all this is, again for example, 3.00 to 1 means the driveshaft turns 3 times for each time the ring gear [and wheels], turn. Ford picked an excellent ratio for overall use on the street with the 3.55s.

nanaki

get 4.10 the 05 has 3.55 stock.

HubbaHubba

Pros and Cons:

4.10 pros: better excelleration

4.10 cons: cost of gears and installation, reduced top end, reduced gas mileage, warranty issues, speedo/ odometer calibration issues. You may have to purchase larger stickier tires and do suspension mods to get the most out of the swap (4.10s make it easier to turn the tires over and the cars excelleration won't improve if the tires are spinning).

3.73 pros: again better excelleration, maybe a good compromise between 3.55s and 4.10s

3.73 cons: may not be a significant enough improvement to warrant all the expense and aggravation


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Nickdotcom

Thanks for all your help, now i just have to make my decision....

nanaki

4.10 cons: cost is the same as any gear + installation. price isn't going to go up for the 4.10s. they all cost the same. the install all costs the same. gas mileage will not be reduced because of the gears. gas mileage will be reduced because of the driver always wanting to lay in on the gear. once you get used to the gear and start driving normally without wanting to accelerate quick, your gas mileage will be just as it was. you don't HAVE to purchase new tires and upgrade suspension, but you're right, you do if you want the full effect of it. reduced top end? if you're going to be running on the track on the 1/4 mile, you won't be going higher than a little over 100mph anyway. warranty?

warranty? they 4.10 will void your warranty just as much as any gear upgrade or even downgrade. the only warranty it voids are different parts on the car. if they can link the failed part on your car to your aftermarket part, then you gotta pay. like, your shaker is having problems, gears aren't going to void your warranty on that. your whole rear end falls off, then you're screwed.

there are nomore calibration issues with 4.10 as there are with 3.73, 3.55 or any other gear. get a chip or a speedo calibrator. that's why they have different tunes for chips for different gears. there's no hassel entering the code(s) for 4.10 as it is to enter it for 3.73 or 4.30.

whew... next time research a bit better before posting.

GWFoos

If you want to put a supercharger on the auto later on, then 3.73 is the way to go. That is the route I am going as I am going to put the supercharger on there.

nanaki

depends on the blower. md is running a blower with 4.10s and isn't having any problems.