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Gearing question, im stupid, make me smarter...

712 views 7 replies 4 participants last post by  spk454 
#1 ·
So i dont know poop about the gearing on my XJ. Its a 99' with 3 inches on 31s. Stock axles.

Should i consider regearing? or would it not make any difference? I really dont know anything about it, like how or why you would do it.

Could somebody just give me a quick noob explanation for why gearing needs to be changed with larger tires and maybe a recommendation on what i should do.

Sorry for the stupid question, any help appreciated.
 
#2 ·
If the power feels okay to you, then you do not need to regear. How does it accelerate in your opinion?

Most people would not regear for 31" tires. They are close enough to the stock size that most people just deal with the small power loss.

Regearing can make a very noticeable difference. The amount of difference can actually be calculated. Going from 3.07 to 4.10 is a 33% change. You will feel exactly that much of a difference. Its not like adding a supercharger or any other mod to the engine where it has to travel through the entire drivetrain. Its right in the axles and it directly effects how much torque you put to the wheels.

The reason you need to regear with bigger tires is because the bigger tires change your final drive ratio. Adding bigger tires has the same effect as changing to a numerically lower ratio. To compensate for this, you regear the axles to a numerically higher ratio.
 
#3 ·
ok, thank you, thats what ive been looking for, just a simple explanation.

If the power feels okay to you, then you do not need to regear. How does it accelerate in your opinion?

Most people would not regear for 31" tires. They are close enough to the stock size that most people just deal with the small power loss.

Regearing can make a very noticeable difference. The amount of difference can actually be calculated. Going from 3.07 to 4.10 is a 33% change. You will feel exactly that much of a difference. Its not like adding a supercharger or any other mod to the engine where it has to travel through the entire drivetrain. Its right in the axles and it directly effects how much torque you put to the wheels.

The reason you need to regear with bigger tires is because the bigger tires change your final drive ratio. Adding bigger tires has the same effect as changing to a numerically lower ratio. To compensate for this, you regear the axles to a numerically higher ratio.
 
#4 ·
the power feels ok, but i would like more, i might go with bigger tires and then gearing would probably be a must.

are there axles that i can buy to replace mine that will be geared appropriately or would i have to change the gears i already have? ive read that regearing can get real expensive quick. and that its not really a DIY kinda job.
 
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