steal101

What gains do you get from going to 3.73's or 4.10's? Any lost power?

slegos888

better off the line acceleration if you have a mtx gt you wont feel much over the 3.55 with the 3.73 so id go with 4.10's

steal101

It's a manual tranny. How about 1/4 mile times?

steal101

How much loss of HP and gas mileage do you lose with stock to 4.10's?

bamaburnum

You won't lose any HP and the gas mileage depends on if you drive mostly city or highway. City driving won't be affected much at all.

creedog

Go w/ 4.30's!!! Don't fear the gear.

dhof303

I have always felt that gears are the best investment for the money as far as these things are concerned:

1 Won't damage your car like NOS or boost are likely to do. This is dependent upon who puts the gears in and how much knowledge/skill you have dealing with boost.
2 Gears will provide the most "feel" of change in accelleration with your car hands down given all of the modifications you can do, as long as in previous posts reccomend that you choose a ratio significantly different than your current gear.
3 Any other modification you do to the car as far as hp/tq are concerned gives a more dramatic result due to what is called torque multiplication.
4 If you choose to limit the amount of money/time/mods done to your car then gears will help your car accellerate at a rate comparable to cars with a bit more horsepower and a "taller" gear.

I agree with creedog and slegos, go with at least a 4.10. Get a shop to do it that will warranty the gears/rearend because Ford will void any warranty on the gears/rear axle that could possibly be related to a gear/installation error.

steal101

Thanks, Derek!

steal101

I remember someone saying that you will lose a little HP. Also what about top end?

6505pony

Haven't heard anything about the HP and who drives over 145 mph?

It will just be running at a little higher revs when it hits the speed governor unless you have it flashed.

Unless you live in a very isolated area I would much rather have the 1/4 mile time than the overall top speed.

BTW you will loose a little gas mileage on normal highway driving but what I don't know.

steal101

That makes sense.

dhof303

This is a myth, you will in no way lose hp. Hp is a set number that can be influenced with performance modifications but gears will only influence how the hp/tq is put to the ground. Terminology is crucial here, you will have a fixed amount of torque but due to the torque multiplication you will make better use of the torque produced. Gears can help a car with low horsepower and torque quicker and "feel" more powerful. Gears also help place the car's engine in a more useable RPM range which for drag racers is a higher RPM and thus they need a low gear ratio that will put the car in a higher RPM where their power curve is.

steal101

Derek, your the man.

Purple Hayz

Question. Once I have the 4.10's installed, won't the speedo be off? If so, is there a way to correct it w/o flashing the ECU, which may void my warranty (I know the SCT tuner retains the stock settings, but a service tech will probably be able to tell if the chip has been re-flashed)

6505pony

I believe if the only thing you are having done that you need a flash is changing the gear you can get a Ford tech to maybe do the flash especially if your get Ford's 4.10 gears.

That wion't void your warranty.

dhof303

There has been some discussion about this concerning the newer vehicles. Some have been told by Ford technicians that if you have gears that are lower than 3.55 then their computer flasher from Ford will not adjust the speedo. A Ford technician that I know has reported to me that even after the training on the new mustangs that they received the computer will store an event that it was reflashed but this can be erased by leaving the battery unplugged for over 30 minutes or so.

Purple Hayz

There has been some discussion about this concerning the newer vehicles. Some have been told by Ford technicians that if you have gears that are lower than 3.55 then their computer flasher from Ford will not adjust the speedo. A Ford technician that I know has reported to me that even after the training on the new mustangs that they received the computer will store an event that it was reflashed but this can be erased by leaving the battery unplugged for over 30 minutes or so.
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Outstanding news. If true, that would mean that we could even incorporate performance mods into the tune (a/f, shift points, etc) and then reset to factory specs if needed, without alerting the techs that we flashed the ECU. This makes me far more comfortable about using the xcalibrator/predator etc.

Thanks for the info, Derek.

Stangfriik

What are the RPM's when you're cruising at around 90mph when you have 4.10's in?

dhof303

Any car's RPM can be determined with a mathmatical equation process but some more information must be obtained to be completely accurate. This info includes knowing the final drive ratio of the transmission and the tire circumference or diameter/radius. If you are like me and hate math then try this website, I wish it would have been available when I was a kid and my dad had to give me this lesson with a pencil/paper/ruler/calculator. :bang:

http://www.csgnetwork.com/multirpmcalc.html