Nuts & Bolts: Rear Gears on Mad Maxxis Off-Road RunnerPosted in How To: Tech Qa on March 16, 2016
Mad Maxxis Ratios
I like seeing all the radical rides in the magazine. Everything I own is four-wheel-drive except my welder, but I'm working on that! I was reading “Mad Maxxis Off-Road Runner” and noticed that you're running 40-inch tires in the rear and 35-inch tires up front. The article mentions that you're running 4.56 G2 gears in the front but doesn’t mention what gears are in the rear. How are you running two different-size tires without running different gear ratios, or did I miss something?
Good question! We often can’t include every little detail in the limited space of an article, but we should have better explained how we made the mismatched tire sizes work. We ran 4.56 gears in the Currie Dana 60 front with 35-inch tires and 5.38 gears in the Dynatrac ProRock 80 rear axle with 40-inch tires. How did we figure this out? Here’s the math.
40 ÷ 5.38 = 35 ÷ X
35 x 5.38 ÷ 40 = 4.7075
As you can see, in order to be perfect, the front gear ratio needs to be 4.70, but 4.70 gears don’t exist for a Dana 60. The closest available ratio is 4.56s, which is what we chose. The final drive ratio isn’t perfect front-to-rear, but it is very, very close. So close, in fact, that we haven’t noticed any handling quirks or binding while in four-wheel drive.