What is 4.56 gearing??

[Atlantean]

I am looking at buying a jeep that has 4.56 gearing in it, and it has 35" 15x10 tires. What does the 4.56 gearing do?

 

[notfred]

the higher the number, the lower the gears. Lower gears provide for better acceleration, more torque at low speeds, and worse gas mileage.

edit: my car came stock with 2/73 gears, it has 3.73 gears in it now. I don't know what stock gears on that jeep are.

Note that bigger wheels than stock will offset lower gears. If you put bigger wheels on the car and lower gears, you may end up w/ very similar acceleration and mileage as before.

 

[JC]

Originally posted by: Atlantean
I am looking at buying a jeep that has 4.56 gearing in it, and it has 35" 15x10 tires. What does the 4.56 gearing do?

Those tall tires effectively reduce the gear ratio, the lower gears are to compensate. At 4.56 though, top speed will be likely around 60 MPH


JC

 

[JC]

Originally posted by: JC

Originally posted by: Atlantean
I am looking at buying a jeep that has 4.56 gearing in it, and it has 35" 15x10 tires. What does the 4.56 gearing do?

Those tall tires effectively reduce the gear ratio, the lower gears are to compensate. At 4.56 though, top speed will be likely around 60 MPH


JC

Dammit, Notfred got me with the edit!

edit: this was supposed to be an edit.

 

[HappyPuppy]

4.56 gears = your driveshaft will turn 4.56 revolutions for each single revolution of the axle/wheel.

 

[notfred]

Originally posted by: JC

Originally posted by: JC

Originally posted by: Atlantean
I am looking at buying a jeep that has 4.56 gearing in it, and it has 35" 15x10 tires. What does the 4.56 gearing do?

Those tall tires effectively reduce the gear ratio, the lower gears are to compensate. At 4.56 though, top speed will be likely around 60 MPH


JC

edit: dammit, Notfred got me with the edit!

And I still beat you!

 

[JC]

And I still beat you!

D'oh! I guess you're geared lower than I am

 

[Eli]

Originally posted by: JC

And I still beat you!

D'oh! I guess you're geared lower than I am

 

[TopGun]

At 4.56 though, top speed will be likely around 60 MPH

Not true. With stock tire size maybe, but like you said regearing the axles is to compensate for the larger tires and bring engine RPM back into spec.

 

[flot]

Ignore the top speed comments. Assuming you're talking about a CJ/YJ/TJ (Wrangler) then 4.56 gearing is roughly appropriate for a 6 cyl engine with 35" tires. If you're talking about a 4 cyl with 35" tires, something like 4.88 would be more appropriate. The gears serve to compensate for the overly large tires. A "stock" TJ Wrangler would have 3.06 or 3.73 gears with the Inline 6 cyl, or 4.11 gears with the 4 cyl. That would be with a stock 30" tire. (technically, there are 2 stock tire sizes, but that's not important right now)

Basically it means that 4.56 revolutions of the engine = 1 revolution of the wheels. So if your gearing was 2:1, then at 1000 rpm your wheels would be turning at 500 rpm. Make sense? You can find the diameter of the wheel, and use that to get actual speeds for given revolutions. Or go to some Jeep websites (I know there is one at www.dirtroad.com) and you'll find a gear ratio / tire size calculator.

Any jeep questions, feel free to shoot me an email. (not PM, don't check those as often)

 

[Pacfanweb]

My Moroso power/speed calculator says that with 35" tires at 3000 rpms=67 mph. 3000 rpms is BUZZING in a Jeep 6 cylinder, especially if you're planning on driving much distance. 3500 rpms will get you near 80. When you let off the gas at that RPM, it will feel like you hit the brakes.

 

[Cyberian]

Originally posted by: HappyPuppy
4.56 gears = your driveshaft will turn 4.56 revolutions for each single revolution of the axle/wheel.

Nooooo!

My mind is now awash with differential, ring & pinion, banjo, rear end, quick change, PosiTraction, welded spiders, .....

 

[Pacfanweb]

Basically it means that 4.56 revolutions of the engine = 1 revolution of the wheels

You mean 4.56 turns of the DRIVESHAFT, not the engine. I'm sure that was a typo, but just making sure.
Measurement of the axle ratio has nothing to do with the engine speed. You could shut the engine off and coast down the road, and the driveshaft would still be turning 4.56 times for every turn of the wheels.