Cool Cousins - Toyota Tacoma and FJ Cruiser Transmission Cooler R&D, Part 1 - Tacoma Design Plans and Prototyping
The toughest trucks on the planet are typically sporting a Toyota badge. The Hilux might be the model responsible for Toyota's rugged reputation, but that same DNA runs through the oil passages of the trucks we see on and off the roads here in the States. Specifically, the multifaceted Tacoma has become our crowd favorite, from commuting to the office to hauling you and all of your things across the wilderness. While plenty of things make all of this possible, the transmission is the driving force to accomplishing these tasks, so keeping the drivetrain in good health is imperative.
Extreme heat is the enemy to any component driving the Tacoma, especially the transmission. The fluid running through the planetary gears and clutch packs pulls double duty between cooling and lubricating the long list of components whirling around inside the casing. Like any other lubricant, the automatic transmission fluid, or ATF, works best at its specified operating temperature, achieving the optimal balance of viscosity and lubrication characteristics. Cold fluid is tougher for the gears to churn through, and as temperatures climb, the extreme heat will oxidize and burn the fluid, giving the gears the perfect opportunity to grind each other apart.
High heat building in the transmission comes from the activities these Tacomas were designed to do. Clawing their way up steep, soft inclines, inching over large trail obstacles, and towing or carrying heavy payloads over these rugged terrains all turn up the heat on your Tacoma's transmission. However, Toyota was already one step ahead of these temperatures from the factory by equipping two stages of heat management for the transmission fluid.
First, the hot fluid is siphoned from the transmission to the external cooler mounted behind the grille on the radiator support. This small cooler whisks away some heat from heavy loads before routing to the second cooler in the radiator's cold-side end tank. This second cooler is aimed at proper heat management in both extremes. Again, ATF performs best at operating temperature, so matching the temperature of the cooling system helps reach the optimal temperature sooner for better performance but will put additional stress on the cooling system as temperatures climb above the optimal point.
To better manage the transmission's temperatures, our engineering team has been hard at work on an improved external cooler that's better suited for managing extreme temperatures. Our process starts with the simple fact when it comes to heat exchangers - bigger is better. Unfortunately, the OEM cooler falls short primarily due to its small stature, so our engineer, Dave, has big plans for keeping the Tacoma's transmission from getting a fever.
The increased size is only the first step to improving the transmission's cooling system. Dave is opting to utilize tube-and-fin core construction with plenty of extra fins to boost the heat dissipation properties. Our new core will be capped on either end with extruded aluminum tube end tanks, providing safe passage for vital ATF without packing on too many pounds. To top off this new design, Dave plans to add a pair of hardlines to the end tanks for simple integration into the OEM system.
The next step to designing a larger transmission cooler is ensuring that this new design and accompanying mounting brackets fit as intended. While our 3D scanner and modeling software can create a precise digital workspace of the front of our donor Tacoma, nothing quite beats physically installing the product on the vehicle. So, instead of waiting for a production sample kit to arrive at our R&D facility, we opted to put our fabrication arsenal to work to generate a fabrication prototype.
The transmission is the literal driving force of your tough Toyota. No matter which engine is mated to it or the body it's mounted to, keeping the fluid running through the clutch packs and gearsets from cooking is vital to your truck's livelihood, no matter the journey. So make sure you stay tuned as we progress through our design journey, first stopping at the FJ Cruiser before making our way to our final design.
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