A Look Into the On The Rox Roxor Drivetrain
We would like to take some time to describe some of the accessories and custom modifications that have been made to the OTR Mahindra Roxor. All of the modifications and added products have been installed to enhance our Roxor’s offroad capability. For the most part, many of these modifications are DIY. Although some of the more technical items such as gear and axle installations may require a professional. This will be the first segment highlighting our Roxor, and will focus on what it takes to reliably run a 37″ tall tire on a Roxor!
Let’s begin with the wheel/tire combo that we are running. Our tire of choice is a 37” x 12.5” BF Goodrich KM3. To go along with the aggressive tire, we went with a set of 17” x 9” wide Trail Gear Beadlock Wheels. This allows us to confidently air down to single digits. These wheels offer 3.75” of backspacing. In order to push the 12.5” wide tires out from the leaf springs, we also needed to run 1.25” Trail Gear Wheel Spacers. Generally, we don’t recommend running wheel spacers, but with the size of tire it was necessary. We have a lot of miles on this setup, the lug nuts have not lost their torque, and Trail-Gear prides themselves on making good quality parts.
To clear the 37″ tall BFG KM3’s, we needed to make some body modifications. To start, we tig welded up a set of our DIY Front Tube Fender Kits. This gives us a ton of body clearance up front, but we still needed more room without further lifting the rear of the Roxor. In order to do this, we built a custom set of Rear Tube Fenders and clearance the tub. This gave us the needed toom to clear the 37″ tall tires while only leveling the front with our Roxor Shackle Reversal Kit.
For our Roxor to handle the larger tires and allow us more locker options, we partnered with Yukon Gear and Axle to develop a 30 Spline Front Chromoly Axle Shaft package. These axle shafts replace the weak 19 spline steel axle shafts that the Roxor comes from the factory with. The 4340 Chromoly Axle Shafts are much stronger, thanks to the material as well as the increased spline count. They also give the user the ability to utilize 30 spline standard Dana 44 carriers, which we will touch on later. Thanks to another new partnership with RCV Performance customers also have the option to run a set of RCV Front Chromoly Axle Shafts. We upgraded the rear axle to house our Full Float Conversion Kit. This conversion kit utilizes Yukon 4340 Axle Shafts that we also helped to develop. These axles are a 30 spline inner and 27 spline outer design, again allowing us to run Standard Dana 44 Differentials. The kit comes standard with drive flanges.
In order to change out the factory axle shafts and install a standard Dana 44 differential, we needed to change out the Ring and Pinion. After some careful calculations, we decided on a Yukon 5.38 gear ratio to go along with our 37” x 12.5” BFG KM3’s. With this combination and the Roxor’s 5-speed manual transmission, it puts us right at 2550 RPM at 65 mph give or take 100 rpm. This proves to be a safe engine speed that keeps us in the power curve. We no longer need to downshift when we approach slight inclines in the road as you do with the factory 3.73’s and 29” tall tires. An easy calculator to use to decide on the correct Ring and Pinion is this one here– RPM Calculator.
Thanks to the 30 spline axle options, we were able to install Yukon Zip Lockers in the front and rear of the Roxor. With our Chromoly Axle Shafts, we have seen customers install OX Lockers, ARB Air Lockers, Yukon Duragrip Differentials, and even Yukon Open Carriers with a 30 Spline Spartan Locker.