Anytime I have ran a large tranny cooler, I have thought that the tranny took a long time to come up to temp and ran a little cool unless I was flogging it. I even picked up an engine oil thermostat to plumb in the lines, but the bypass was so large that the cooler got full flow all the time.

So, I just run a smaller tranny cooler now. But it is slow to bring the temps down when I am beating on the car.

Other than the tranny coolers with fans and temp switches to trigger the fan, is there any such thing as a thermostat for our tranny cooler lines? Seems that would make sense. Bring the temp down quick or not let it get too high to begin with, while not running the tranny too cool under light loads. Would bring it up to temp quicker, too.

Obviously a street/strip application.