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post #1 of 3 (permalink) Old 12-02-2008, 11:36 PM Thread Starter
 
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Axle ratio question

Ok so after doing some reading on here and a few other sites about axles. And I have a few questions.....

1- What is axle ratio?
2-What does it affect?
3-What is better, or worse to have
4-Is it changable, if so why would you want to, and how could it be done?
5- What the heck is limited slip?

My 08 Ranger Sport I beleive came with a 4.10 axle ratio, but I have seen 3.73, and 3.55 as well. What the heck does it all mean?

Please laugh quietly.....

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post #2 of 3 (permalink) Old 12-02-2008, 11:51 PM
 
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Quote:
Originally Posted by Rustycan View Post
Ok so after doing some reading on here and a few other sites about axles. And I have a few questions.....

1- What is axle ratio?
2-What does it affect?
3-What is better, or worse to have
4-Is it changable, if so why would you want to, and how could it be done?

My 08 Ranger Sport I beleive came with a 4.10 axle ratio, but I have seen 3.73, and 3.55 as well. What the heck does it all mean?

Please laugh quietly.....
no laughing from me....
1 axle ratio is more commonly called gear ratio. it's basically the number of turns the driveshaft makes in relation to the tires. if you have a 3.73 gear ratio, that means the tires make on revolution for 3 3/4 turns of the driveshaft
2 it will affect fuel economy and acceleration as well as RPM
3 that depends..most stock gear ratio's from the factory are pretty well set up for the stock tire size and fuel economy. If you go to a lower ratio ( numerically higher) that will increase RPM and acceleration at the expense of fuel economy. if you want to go to a taller tire size, it's a good idea to put in a lower ratio to keep your acceleration and driveability in check. not re-gearing is hard on tranny's to because they are working harder and mileage will suffer.
4 see above....a good ratio for 31" tires is a 3.73....33" tire is a 4.10...35" tire is a 4.56. you see as a tire gets bigger that the gear ratio gets lower? this keeps the engine in it's power band, optimizing fuel economy and engine life. If you've got 4.10's now and are happy with them...i'de say leave them. i forgot to say that the axle ratio is figured out by dividing the #of teeth on the pinion by the # of teeth on the ring gear.

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post #3 of 3 (permalink) Old 12-03-2008, 12:08 AM
 
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Quote:
Originally Posted by Rusty can View Post
Ok so after doing some reading on here and a few other sites about axles. And I have a few questions.....

1- What is axle ratio?
2-What does it affect?
3-What is better, or worse to have
4-Is it changable, if so why would you want to, and how could it be done?
5- What the heck is limited slip?

My 08 Ranger Sport I beleive came with a 4.10 axle ratio, but I have seen 3.73, and 3.55 as well. What the heck does it all mean?

Please laugh quietly.....






1) an axle ratio refers to the gears that are in the rear differential

2) it affects the drive ability of your vehicle some vehicles have anywhere from a 2.73 to 4.88 or lower gears the higher the number the lower the gear and more torque you will have

3) It depends what you are doing with you vehicle most trucks these days have a 3.73 ratio from the factory (lower gears numerally higher #'s mean more pulling power or torque)

4) YES it is here's 4 Reasons To Change Your Gear Ratio.

If you have larger than stock tires on your vehicle, the benefits of gearing CANNOT BE MATCHED BY ANY OTHER MODIFICATION TO THE VEHICLE!

By re gearing it is guaranteed that:

1. TORQUE TO THE REAR AXLE WILL BE GREATLY IMPROVED
Even a simple change from a 31" diameter tire to a 33" diameter tire will affect the amount of available torque by 10%.

2. STRESS TO THE DRIVE LINE WILL BE GREATLY LESSENED
Modern day transmissions cost $600 or more to perform a basic overhaul. Driving with even a 10% larger tire will result in the transmission being under the same load as always being driven on an incline. The transmission may not suddenly fail, but the life will definitely be reduced by thousands of miles.

3. ENGINE EFFICIENCY WILL BE REGAINED
RPM alone does not affect fuel mileage. An under geared vehicle (as the result of over sized tires) will result in a substantial loss of fuel mileage. Also, just as with the transmission, your engine life will greatly be reduced.

4. SPEEDOMETER/ODOMETER ACCURACY WILL BE REGAINED
With kits in the $100+ range to calibrate speedometers after tire swaps, it seems pretty important to have an accurate speedometer, which can also be fixed with a simple gear change.



5) A limited slip or positraction differential typically uses some form of clutches that bind up the differential, providing traction to the both tires. The clutches will slip to some extent to allow tires to turn at different speeds on corners


Did i do a good job in confusing you?

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