As the stock 200-series already has an aux tranny cooler, perhaps this is better described as installing an aux aux cooler. The stock cooler is solid. I imagine this is niche for the heaviest of rigs or those that do more aggressive off-road running that really loads up the torque converter. From my monitoring, continuous high engine outputs is what largely drives heat into the tranny.
This is a follow-on to this planning thread:
forum.ih8mud.com
I've gone the path of adding an additional tranny cooler inline and sequential to the stock tranny cooler. To better support cooling when motivating 15,620lbs combined weight when towing an 8k Airstream. Instead of replacing the engineered stock aux cooler, I felt it better to retain the stock cooler as a known performance quantity. As not all coolers are created equal, it was hard to know if replacing it would result in x% cooling relative to stock, or possibly worse. By adding another cooler, I was guaranteed some percentage improvement over stock, and that's what I got. It was also important that I don't add so much cooling that cold weather performance could suffer causing the thermostat to over-cycle.
An important consideration was not impacting engine radiator performance, by over shrouding frontal area. Keeping the install simple and robust. Also to leverage active airflow for things like low speed crawling in sand, where the stock tranny aux cooler is outside of the radiator fan airflow.
The cooler circuit is now setup as
transmission > radiator > OE aux cooler > aftermarket aux cooler > back to tranny
This is a follow-on to this planning thread:
Tranny Cooler Upgrade Planning
Also PWR make a twin cooler kit, it’s pricey and I’m searching for pics, but the details are here: https://shop.pwr.com.au/extreme-transmission-oil-cooler-kit-toyota-landcru Of course if the transmission was designed properly the torque converter would be locked much earlier, eliminating the...

I've gone the path of adding an additional tranny cooler inline and sequential to the stock tranny cooler. To better support cooling when motivating 15,620lbs combined weight when towing an 8k Airstream. Instead of replacing the engineered stock aux cooler, I felt it better to retain the stock cooler as a known performance quantity. As not all coolers are created equal, it was hard to know if replacing it would result in x% cooling relative to stock, or possibly worse. By adding another cooler, I was guaranteed some percentage improvement over stock, and that's what I got. It was also important that I don't add so much cooling that cold weather performance could suffer causing the thermostat to over-cycle.
An important consideration was not impacting engine radiator performance, by over shrouding frontal area. Keeping the install simple and robust. Also to leverage active airflow for things like low speed crawling in sand, where the stock tranny aux cooler is outside of the radiator fan airflow.
The cooler circuit is now setup as
transmission > radiator > OE aux cooler > aftermarket aux cooler > back to tranny
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