American-Made Billet Case Reinforcements for Mitsubishi 5-Speed Manual Transmissions and All Transfer-cases prior to 93 (check that your transfer-case has a large 8 bolt plate on the side of the case opposite of the front driveshaft. )

Billet reinforcements plates are commonplace in transmission upgrades, typically for one or more of three reasons; high rpm, high torque, or high horsepower. It’s likely your Mitsu 4wd is not turning very high horsepower, unless you’ve swapped in the 2.6 turbo engine or other modified mill, or just dialed it up with a sniper efi kit.

Depending on the low range gears your case is running and the tire size you’ve got; the transfer-case might be under a high torque load when you’re off-road and using 4-low.

We’ve partnered with Dmitriy from D-Fab Designs to develop a reinforcement plate similar to the beautiful transmission pan kit he’s made and we’ve paired it with that plate for maximum savings and reinforcement.

This 13mm thick transfer-case plate is available exclusively through ADD and comes with all needed hardware to install. Use this plate to reinforce the large open cavity on the side of the stock transfer-case and add passive cooling to the system. Currently the large cavity is covered by a simple piece of stamped steel, likely bent on the edges and rusting, the cavity it covers was intended for a PTO case, it would be bolted to the side and operating a PTO winch for other countries, we are unable to retrofit this system to our trucks so all of them have been equipped with the stamped plate. Behind the stamped plate is the largest of the 4wd and Low range gears, it rides on a steel shaft running through the aluminum case and rolls on two caged needle bearing assemblies. Having a large open cavity next to this gear lends to the potential for case flex and premature bearing failure, leading to gear and bearing noise; symptoms of bearing failure that can lead to metal in the system and overheating to eventual failure of the low range gear set.

This has been documented in the manual transmission variants and has resulted in a need for case reinforcement; the KM132, KM145, KM148, V5M21 and V45M21 were used in a wide range of horsepower and torque applications, from the higher horsepower and rpm of 2wd turbo gasoline 2.6 liter powered Starions to the grunt-torque of the turbo diesel 2.3 and 2.5 in the Might Max, Pajero and Delica.

The new plate not only reinforces the case, it also adds cooling through 8mm raised cooling fins, these increase the surface area of the portion of the case where most of the fluid resides. In low range you’re traveling at low speeds with minimal air flow, and it’s the only time you’re working that lower set of gears, this helps to  ensure your transfercase stays cool and strong while you’re putting it to use. The raised fins are large enough to promote cooling while being small enough for easy cleaning and small enough to prevent most mud and dirt packing. Use of this plate is highly recommended if you’re using or planning to use Marks4wd 2.8 low range gearing.