Dana 30 Differential: Stock / OEM Gear Ratio

[mikehkk]

Hello,

I'm the sole owner of a 1999 Jeep Wrangler TJ Sport w/4.0 Engine & AX15 Manual Transmission. Outside of changing the gear oil every few years, the original Dana 30 (front) diff is OEM/stock and has never been rebuilt or modified in any way.

I'm getting ready to have a shop rebuild the diff for the first time now. I'm going to have everything replaced in it (bearings, carrier, spider gears, and Ring & Pinion, etc.).

So, my question is: What's the original/stock GEAR RATIO for ring & pinion that came with the differential?

Thanks very much,

Mike

 

[deadbeat son]

Hello,

I'm the sole owner of a 1999 Jeep Wrangler TJ Sport w/4.0 Engine & AX15 Manual Transmission. Outside of changing the gear oil every few years, the original Dana 30 (front) diff is OEM/stock and has never been rebuilt or modified in any way.

I'm getting ready to have a shop rebuild the diff for the first time now. I'm going to have everything replaced in it (bearings, carrier, spider gears, and Ring & Pinion, etc.).

So, my question is: What's the original/stock GEAR RATIO for ring & pinion that came with the differential?

Thanks very much,

Mike

It depends. There were various options that you could have.

Enter your VIN here to see your build sheet.

 

[TexasTJ2004]

It is pretty simple to determine.
Drive in 5th on highway at 70MPH or any other speed. Note the precise RPM at this speed. Note which tires you have.
Go to grimjeeper calc, and you can match your gearing there.
There is a simple equation behind this at the end.

 

[cpwolf]

It depends. There were various options that you could have.

Enter your VIN here to see your build sheet.

This is the simplest solution. Enter your VIN and get your build sheet. You can then confirm with other methods if you want.

 

[Blackjack]

Look to see if the tag is still on the cover bolts for the diff. It will tell you on there.

 

[Jerry Bransford]

Look for the below steel tag bolted onto your differential cover at its 9 o'clock position. Embossed into it will be your axle ratio. This one is indicating a 3.73 ratio.

 

[mikehkk]

It depends. There were various options that you could have.

Enter your VIN here to see your build sheet.

Thanks for that. Very interesting. While it doesn't say anything about the front diff (Dana 30), it's very specific about the rear diff: 3.07 REAR AXLE RATIO.

 

[RINC]

Thanks for that. Very interesting. While it doesn't say anything about the front diff (Dana 30), it's very specific about the rear diff: 3.07 REAR AXLE RATIO.

Go now. Do not stop. Pass Go. Regear to 5.13 R&P.

 

[deadbeat son]

Thanks for that. Very interesting. While it doesn't say anything about the front diff (Dana 30), it's very specific about the rear diff: 3.07 REAR AXLE RATIO.

Then that's the stock ratio for your front axle as well.