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Cooling to the Duramax – Transmission Cooler, Part 2: Measure Twice

No matter how many trucks I write about, I’m always surprised how often a critical part of the drivetrain is underdeveloped. It’s even more surprising when a truck built for towing and hauling has a major flaw in the transmission system. The transmission is the heart of towing, and when you’re asking it to carry over five tons of truck and trailer up a grade, any weakness in the system is sure to show itself. However, the Allison transmission mated to 2001-2014 Duramax engines is not that weak point.

On the 2001-2005 models the cooler is mounted directly in front of the AC condenser, meaning it receives the proper airflow, however the size of the cooler still restricts it's ability to cool the transmission fluid.

The transmission cooler equipped on the 2001-2014 Duramax trucks could honestly be described as “dainty.” That’s not a word that any owner wants to hear when talking about a part of their truck, especially not a part they rely on to keep driving. In 2006, when an extra gear was added to the Allison transmission, Chevy/GMC equipped a larger transmission cooler but, for some reason, decided to tuck it behind the bumper. Neither iteration of the stock transmission cooler is ideal, so we’re making one that is.


With the stock coolers evaluated, Steve measured the space available for our cooler as well as the routing of transmission fluid lines. Instead of breaking out his pen and pencil, Steve decided to go high-tech with our Faro 3D scan arm. The Faro arm swept across the front of our volunteer LB7, every detail rendered on Steve’s computer screen. A few more scans of the transmission cooler alone gave Steve most of what he needed.


There was some manual measuring required, however. We knew that there were two different coolers made for these trucks, but not that the inlet and outlet fittings were the same. Time for the caliper and notepad. Removing the fittings from the cooler revealed two major facets of the fitting, the inner diameter and threads. Steve carefully measured, making sure to capture every detail that we would need to be sure our cooler fit without a hitch.


Those measurements completed the analysis of the LB7 cooler, but we didn’t stop there. Over the next few weeks, we scoured OEM drawings and brought trucks into our engineering facility to take more measurements. With every generation of Duramax from 2001-2014 examined, we needed two different fittings and three different hose sets to fit our target vehicles. The hoses were no problem, but the fittings would be a bit of a challenge. Of course, Steve had a plan to join our cooler with the quick-disconnect lines. In the next post we’ll see that plan come to life and look at the heart of our design: the core.


Thanks for reading!


12 thoughts on “Cooling to the Duramax – Transmission Cooler, Part 2: Measure Twice”

  1. I’m very interested in an improved transmission cooler for my 2013 Chevrolet Silverado HD2500 LML Duramax truck, I am running a 200HP tune that bumps the torque to over 1000 ft/lb and am also running a TCM tune that increases the line pressure in the transmission to provide firmer shifts and less slip in the clutch packs, at the cost of higher temps… my truck’s transmission temp runs around 100-110 degrees above ambient outside temp with the TCM tune. I see 200+ easily in the summer, and while I am running high quality Amsoil synthetic transmission fluid, I still do not want to subject the transmission to 200+ degree temps all the time now that my TCM is tuned for higher line pressure.

    1. Hi Timothy,

      It sounds like this cooler would be great for your Silverado. That’s definitely some hot trans fluid, but I bet that much torque is a lot of fun 😀 Keep an eye out for updates, we should have some soon!



    1. Hi Vernon,

      Not quite yet, we’ll be posting again when this is ready for pre-sale so keep an eye out!



  2. I’m ready to buy one… would love to be a pre tester for you… would document my experience… pictures, write up… let me know, 2013 Silverado Duramax

    1. Hi Tim,

      Right now we’re working with a few local vehicles to test this trans cooler, but if we need some more testing done, I’ll definitely let you know!



  3. I have a 2008 Chevy Silverado 3500HD Duramax. I live in Colorado and have to cross 3 passes in any direction to go anywhere. I just came home pulling a 24,000 lb 5th wheel trailer and my tranny temp, with much attention and care, ran 180 to 190 degrees, my coolant temp got as high as 212 degrees the ambient air temp was 30 to 40 degrees . I have the Banks 6 Gun tunner with stock air cleaner. I want to improve the cooling of both the transmission and engine. I am definitely interested in your trans cooler and would be interested in your engine cooling recommendations. Any idea when your tranny cooler will be ready for market?


    1. I should have updates for you in the next couple of weeks! Right now we’re looking at early June for launch of this cooler.

      Thank you!


    1. Thanks for your interest! I should have updates for you in the next couple of weeks! Right now we’re looking at early June for launch of this cooler.

      Thanks again,


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