Dumb gearing question

[nottinbe]

I wouldn't have thought to ask this except for some paranoia from having the wrong wheels installed at the factory (still not resolved), and seeing some other weirdness out there like the guy who got the wrong backseats.

Everything else on my order is easily verifiable. Tow, lux, MGV, MT, etc. I can see it \ touch it \ use it.

So here's the dumb question - how do you know that you in fact have the correct gearing installed? Mine should be 4.7:1 as a manual badlands. But is there any way to check? I have no reason to suspect its not correct, but the wrong wheels made me start checking everything else, and I was just realizing I don't know how to check that.

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[PWillette]

Elevate your rear wheels and spin the tires while in gear, drive shaft should spin 4.7 times for every single tire rotation. Other than that pull the rear diff cover to confirm the ring & pinion.

 

[Monster79]

Idk if Ford stamps the rear end with the information but you can jack up the rear end (do it safely). Mark the tire and driveshaft, rotate the tire a full revolution and count how many times the driveshaft makes a revolution.

 

[IDyeti]

There's a sticker on mine indicating 4.7.

 

[MrJoe]

There's a sticker on mine indicating 4.7.

Any other year I'd agree. Not sure I'd trust a sticker with the other sticker mistakes taking place... Just sayin'.

 

[Werkedperformance]

Once upon a time....

I had a Grand Cherokee with a driveline complaint. "feels like truck is ripping itself apart"

Got wrecked and they swapped in the wrong rear axle.

Different ratio at each axle, it made lots of fun noises.

 

[nottinbe]

There's a sticker on mine indicating 4.7.

Found the sticker, it says 4.7. So at the very minimum they did adhere the correct sticker. That's something.

 

[Spooled]

Math

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

For bonus paranoia... What if they put 4.70's out back and 4.46 up front

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