37 vs 38’s and 4.88 vs 5.13

[SRFRAT67]

great video detailing what is involved in a gear swap on our Mojaves, in the beginning of the video a great explanation by a knowledgeable installer regarding gear selection. I found this very helpful.

Sponsored

 

[Zachanadandy]

Very dependent on Speed and use. Jeeps overall are better suited as a slower, trail type vehicles. Solid axles, 4 link with a panhard bar, and the aerodynamics of a refrigerator on wheels. Yes you can build them to be go-fast vehicles, but you're starting at a disadvantage.

As far as use, comparing the gladiator and the older wranglers. you're talking about a vehicle that is 20% heavier from the factory and has a 300-400% higher tow rating. different vehicles with different uses. The gears (and all other components) should match your use.

As for the Jeep actually spinning the tires and pulling the weight. It's easier for you to apply 500 Ft lbs of torque with a 4' long breaker bar than it is a 6" wrench because of the mechanical advantage. Yes you have to move the end of the tool 20X further to apply that torque, but we can all agree if we had to torque something down to 500 ft. lbs we'd all prefer the breaker bar. Your jeep is no different, if you have to move a 5000lb trailer, the Jeep has to work less with deeper gears to apply the same amount of torque. Yes the Jeep will move the load with factory gears, but there will be additional slip in the transmission which creates heat and reduces the life of the transmission. a 4cyl mustang II with the old 2.83 gears would probably pull a semi truck on a flat road, but if you do it regularly it will eventually break something.... I can drive a screw with a hammer, but at the end of the day it's not the right tool for the job. The deeper gears will in theory reduce the maximum top speed, but again, choose the right tool for the job.

I agree to a point, and again I'm not arguing that 4.10s are optimal for 37s. In my experience 4.56s are for my use. If I regularly towed a 5k pound trailer in stop and go traffic and rarely drove over 70mph I'd lean toward the deeper end. The heat and transmission slip would only be an issue in a stop and go scenario as the torque converter is locked up by 3rd gear. Even towing an overweight trailer 600 miles over a mountain with 4.10s and 37s the Jeep was probably in 1st/2nd gear for 3-4 minutes total for fuel stops. I don't care how steep the grade it's never downshifting to 2nd at 55+ mph. Toyota pulled a 300k pound space shuttle with a tundra rated at 10k pounds without damaging the trans. I doubt 4.10s and 37s would wear the thing out in 200k miles unless b you're running trails with that 5k pound trailer for thousands of miles.