@Pavel Pashkovskiy @Mark B First of all this only matters if you're driving in 4LO, but as a part-time Jeeper, I can confirm to this. I always drive my Cherokee in 4LO + 5th Gear, and 4LO + 3rd gear when towing a Patrol 😅 ( @Frederic can confirm this ).
The 4:1 is LOW/4LO Gear Ratio, the High/4H is always 1:1, that is why 4L is also referred to as Reduction Gear, it reduces to crawling speed. Link to my old Gear Ratio Calculation post below , but I found another photo that explains better (also below). There are other Ratios that affect calculation: Ring & Pinion (sometimes shorthanded as just Axle Ratio) + Transmission Ratio itself (which is different for each Gear Shift) + Transfer Case Ratio
Assuming both Rubicon and non-Rubicon uses Chrysler's TorqueFlite 850RE 8-speed, which is licensed from ZF 8HP50 (used in BMW 5, 7, X3), here is the calculation for both when driving in 4LO 6th Gear (6th gear is where transmission ratio=1.0) for all cars:
Rubicon w/ 4.88 Axles (newer ones):
- 4L 6th gear = 4.88 x 1.0 x 4.0 = 19.52 final 4LO spinning ratio (bigger means more crawling - less speed).
Rubicon w/ 3.73 Axles (older ones):
- 4L 6th gear = 3.73 x 1.0 x 4.0 = 14.92 final 4LO spinning ratio.
Sport/Shara/SandRun/Mojave 3.73 Axle + 2.71 4LO:
- 4L 6th Gear = 3.73 x 1.0 x 2.71 = 10.11 final 4LO spinning ratio.
There is an easy solution to this for Rubicon, just switch to 4LO + 8th Gear:
- 4L 8th Gear Rubicon = 4.88 x 0.64 (8th gear ratio) x 4.0 = 12.5 final 4LO spinning ratio (close to Sahara's 10.11)
OR, Rubicon can drive in 4High with 3rd Gear:
- 4High 3rd Gear Rubicon = 4.88 x 2.10 (3rd gear ratio) x 1.0 (4Hi) = 10.25 (very close to Sahara's 10:11 on 4L 6th).
Assuming huge price differences between Rubicon and non-Rubicon (I just buy old Jeeps so not sure about new prices now), my recommendation is: if it's ONLY for Sand, then Sport & Sahara as cheaper options are better. You will only drive in 4Lo: most sensors are turned off already + when you're stuck or refusal you're already in 4Lo 😁
BUT if you want to do some rock-crawling and also sand-bashing, then Rubicon is a better choice. Those high 4LO spinning ratio / bigger crawling are useful for crawling uphill and braking downhill at steady low-speeds.
Link to Jeep Axle, Transmission, Transfer Case 4L Ratios https://www.jlwranglerforums.com/forum/threads/gear-ratio-chart-for-jl-wrangler.1781/
Link to the Old Gear Ratio Calculator for FJ: