Next Generation Cooling – Transmission Cooler R&D, Part 2: Prototype

There’s nothing more teeth-grindingly irritating than spending hours building and tweaking your truck, only to be let down by the one part you didn’t touch. If you’re lucky, you can continue your trip, only slightly delayed. If you’re not lucky, one-third of the way to your destination you will have to turn back, painfully aware of your throttle input and the pile of smoldering disappointment that used to be your wife in the passenger seat.

Hopefully this blog (or at least the product that comes after it) will help save you from some of that turmoil.


As the weather begins to grow warmer here in Delaware, we’re moving closer to summer. That means beach vacations, roads trips, and inevitably, overheated transmissions. We’ve also been working closer to releasing our 2nd Gen Cummins transmission cooler. Our last post, way back in September of last year, looked at the stock cooler. We concluded that through all the evolutions of the B-Series Cummins engine and the transmissions mated to it, the cooler stayed stuck in 1994.



Over the past few months, we’ve been measuring, designing, and prototyping a better transmission cooler for your 2nd Gen Cummins. The stock transmission cooler for 1994-2002 Dodge Cummins trucks is not exactly small, but for those who tow often or who like to make power, it’s not quite enough. That made our goals clear: design a transmission cooler large enough to cool even the most demanding truck and make it fit like stock. That’s not to say we haven’t faced some challenges, however.


As anybody who’s ever looked at the 2nd gen cooling stack knows, space between the bumper and the intercooler is limited. Of course, that space is also where the transmission cooler lives. To compound the challenge, we wanted to be sure that our cooler would fit with an even thicker intercooler; so, Jason helped Dan install our Mishimoto 2nd Gen Cummins intercooler. At first glance, it seems impossible to fit anything larger than the stock trans cooler. Undeterred, Dan began taking measurements.


Dan firmly planted the tripod of our 3D laser scanner next to his workbench and began scanning the stock transmission cooler on the stock intercooler. This scan gave Dan the data he needed to make sure our cooler’s mounting points match the stock mounting points for a direct fit. Some of this data will also be used to see where the stock cooler can be improved later. With the mounting points scanned, Dan returned the cooler to the truck and measured how much bigger we could make our cooler without interfering with other parts of the truck.


I know, reading about somebody taking measurements is about as exciting as eating chalk. Welding, on the other hand, is exciting. With the measuring phase completed, Dan worked on creating a prototype. Taking a seat at the welding table, coffee nearby to keep him focused, he fired up the welder and struck an arc. A few minutes later, Dan had created…a box. It may look unimpressive, but that box represents the outer limits of what can fit behind the truck’s bumper. Of course, the prototype also has the mounting points necessary to make our cooler direct-fit.


After the welds had finished glowing, Dan bolted the prototype to the stock intercooler to verify the mounting tab locations. Transferring the prototype to the truck, we got our first look at what our cooler could look like in the not-so-distant future.

Now that the prototype has been completed and checked, the next goal was to finalize the design and test a production sample. A few weeks later, we had a fully functioning cooler ready to put through the paces. But more on that next time.

Thanks for reading,


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