ok i know bigger tires on a truck moves the power band around.you lose low end power.put new gears in and take it back to the stock gear and get your low end back.on my truck my tires are 5.85% bigger then stock.i had a 3.55 gear and now it's a 3.33 rear gear.lost some lw end.say i have a stock tires and i put 4.10s in and dyno it . will it move my power band down to the lower rpms.stock dyno say i have 100 hp at 2000 rpm with stock tires.then i put a 4.10 in the rear end,will their be more power at 2000 rpms.i know you don't gain any peak power.but can you move that power around to were you can use it more.it costs a lot to chang gears on a four wheel drive.if you go to a smaller tire then the stock tire will you gain some better take off since you have a lower gear with the smaller tire.don't see spending a lot of money on a gear chang when you can buy a smaller,if it does give you better low end and better take off,and more power at a lower rpm.on paper it looks good,but does it work like that.i don't know so if you do let me know if you know.

 

NEGATORY my friend... It does NOT work like that...Exactly...

You CAN NOT move your HP or Torque curves AT ALL with gearing, PERIOD!

What you CAN do is apply the Torque and HP differently to the rear wheels.

ANALOGY: I have to loosen this VERY tight lug nut. No matter what I do, I am only as strong as I am. I can not make myself any stronger. HOWEVER, I can use what strength I have to my advantage. I first try with a regular 1/2" drive socket wrench and can not budge it! I then slip a 1.5 ft long metal pipe over the wrench AND VOILA... The lug came loose only using about 1/8 of my strength...

The moral of the story is: Applying your torque farther from the center of the application (lengthen the vector) will apply MORE torque at the center.

Same for gears! The higer the ratio is the more torque you can apply to the rear wheels.
(4.10:1 is better than 3.23:1)

As for your power curves. As you move to a higher ratio, you will get to your peak power more quickly with less distance traveled!

SO, a 4:10:1 means your drive shaft will turn 4.1 times while your tires turn only 1 time. This also means your engine has turned more! This will get you to your 2000 RPMs in say 30 ft instead of 45 feet.

You can not change your torque curves without modifying the engine and its components.

You can change the way you apply it!

Hope this helped!

 

Great help from Rand. You will also get your peak power quicker in each gear. Shorter tires do change your effective ratio, but a gear change of .5 to 1 can make a vast difference. If your not a top speed driver than I would recommend 4.10s because: they are quick, tow great, and your trans still has enough gearing for top end.

------------------
2000 F-150 XL,RC,LB,5.4,4R70W,3.55LS,
Class III tow/Payload #3/Convenience pkgs.,
4-wheel disc/ABS,Chestnut/Parchment 40/60,
Ford bedliner & gas/wheel/spare locks,
3" cold air box modification,Superchip,
Dynomax ultra-flow welded 3" cat-back.