What gearing do I have?

[AndyG]

My 03 Rubicon 5 speed with Bf Goodrich Ko 2 ‘s turns 2000 rpm in 5th at 55mph , and 5th is basically an overdrive .

Does this sound like stock 4:10 numbers?

Thinking of going to 4:56,but trying to get a feel how where it may be geared now.

 

[tomtaylz]

Check out this thread: https://wranglertjforum.com/threads/how-do-i-determine-my-axle-gear-ratio.72/

It gives sure fire ways to determine what your axle gearing is, anything I would tell you would just be a guess but it does sound like it has not been regeard.

 

[Chris]

Yep, 4.10s.

IMHO going from 4.10 to 4.56 isn’t a big enough difference to justify the cost.

 

[Rob5589]

Rubicons came with 4.10 so unless it was changed it is 4.10. What size tires do you have?

 

[jjvw]

What size tire? We can only guess without that information. I don't recall what mine was when it was stock, but 2k at 55mph feels very low.

 

[AndyG]

Rubicons came with 4.10 so unless it was changed it is 4.10. What size tires do you have?

33 inch, beadlock rims.

 

[AndyG]

Apologies I left tires size out....I knew better.

 

[Rob5589]

4.56 is the usual rec for your combo. I'd do 4.88 personally.

 

[billiebob]

5th is basically an overdrive .

5th will always be overdrive.

go here..

http://www.grimmjeeper.com/gears.html

But yes, TJR with 33s, 55mph, just under 2K rpm.
You should gear for 4th gear, direct. 5th, OD was intended to lower rpm when you don't need power. 4th, direct is a more efficient gear to deliver power since it is direct, no loss as power goes thru 2 different gear sets and the lower shaft in every other gear, OD included.

 

[ac_]

I would rather know for sure. I would pull the cover and count the teeth on the pinion and the ring then divide the pinion into the ring and that will give you the ratio.

A cleaner way would be to lift one rear side up, mark the driveline and the tire, and turn the tire twice and count how many times the driveline turns. If it turns a little less than 4 it is 3:73 if it turns a little more than 4 it is 4:10 See a pattern here?

4 and a half would be 4:56

There should be a tag also, but that just tells you what it was from the factory. As long as nobody has touched it, it should be true.

 

[jjvw]

5th will always be overdrive.

go here..

http://www.grimmjeeper.com/gears.html

But yes, TJR with 33s, 55mph, just under 2K rpm.
You should gear for 4th gear, direct. 5th, OD was intended to lower rpm when you don't need power. 4th, direct is a more efficient gear to deliver power since it is direct, no loss as power goes thru 2 different gear sets and the lower shaft in every other gear, OD included.

Here we go again. If we only geared for direct drive, then why do we bother asking which transmission is in the vehicle?

Do you agree or disagree that the 32rh and the 42rle should have the same gearing for the same tire size?

 

[billiebob]

mark the driveline

or tape a string to the drive line and you won't need to watch it

 

[billiebob]

Do you agree or disagree that the 32rh and the 42rle should have the same gearing

Since the 32RH has no overdrive, you might want a higher ratio with it and compromise on the power.
And since the 42RLE has such a stupid tall OD you are likely going to compromise with a lower ratio too.

But base those decisions on what happens in the direct ratio first, then make the compromise.

 

[jjvw]

Since the 32RH has no overdrive, you might want a higher ratio with it and compromise on the power.
And since the 42RLE has such a stupid tall OD you are likely going to compromise with a lower ratio too.

But base those decisions on what happens in the direct ratio first, then make the compromise.

It sure sounds like you are taking the final drive gear into consideration. Why make it more complicated than it already is?

 

[nk24]

My 03 Rubicon 5 speed with Bf Goodrich Ko 2 ‘s turns 2000 rpm in 5th at 55mph , and 5th is basically an overdrive .

Does this sound like stock 4:10 numbers?

Thinking of going to 4:56,but trying to get a feel how where it may be geared now.

33 inch, beadlock rims.

Based on the above information and assuming your speedometer has been corrected appropriately, your gearing is likely 4.88 based on the grimmjeeper tool.

 

[billiebob]

Why make it more complicated than it already is?

It is not as simple as most seem to think.

 

[jjvw]

It is not as simple as most seem to think.

I don't entirely disagree.