So I am tuning my jeep using super chips flashpack and wanted to estimate what my gear ratio would be running 33x12:50x18 tires, to do this I need to know my stock gear ratio. I crawled under my JKU and realized someon had the covers off at some point because the ID plate is missing from the two bolts. Is there another way to know what my gear ratio stock would have been on my 2013 Sahara?
Gear ratio question
- Thread starter Jay Garvin
- Start date
Some one could have just changed the gear oil and not put the tag back on, If it was mine i'd pull both covers and change the oil and inspect the R&P. The tooth count is stamped on the side of the ring gear. You never know if they could be full of water from someone offroading through water.
Also this will tell you what Factory had if they still are Factory.
Equipment Listing
Taking this statement at face value you wouldn't need to know your OEM final drive ratio, only your OEM tire size/diameter.
For instance, if your Jeep came with 245/75R17 tires from the factory (31.46" diameter) and you increase the diameter to 33" you have reduced your effective numerical gear by 5% regardless of what that starting point was. Conversely, the correct gear to offset that change would need to be 5% higher...
I'll add that I'm not familiar with the Superchips software so I may be totally missing the point of your question...
You can run your VIN and it'll generally tell you. But you do not need to know your stock gear ratio. You say they diffs have been opened, which means you do not know if the gears were changed. So what you DO need to know is your actual gear ratio. Put the rear end on jack stands. Put a chalk or crayon (or whatever) mark on the driveshaft. Start rotating the tire. Count how many revolutions your driveshaft makes. Boom. Bobs your uncle.