what have you wrenched on your bronco(s) today?

[chuzie]

I am pretty conscious about watching my trans and engine temps. My personal MAXIMUM limitation for the trans is 230*. This is the temp at which I will shut down, no matter what, if I cannot control the temp. Now this is based off a reading at the output from the converter and is the hottest fluid in the system, so it does not necessarily mean my trans is operating at that temp beyond the converter, but it is more conservative. Usually my internal trans temps is 10-15* below the converter. I am more concerned with the maximum temp the fluid reaches rather than the transmission since certain temps will physically change the properties of the fluid. If I ever reach 230*, you can bet I will be spending $100 to change the fluid at my earliest opportunity.

Normal operating range for the 4R70W is 150-200* with 170* as a typical average. I have been on the upper end of that range hanging out at 200-210* and have come to the conclusion a Tru-Cool Max 4739 (40,000GVW) is going to be the ticket. It may be overkill, but I am tired of iteration after iteration resulting in mediocre results or failure.
Sure this trans cooler costs $162 on Amazon, but it has a cold weather bypass and will easily be worth it if I never have to change expensive transmission fluid again due to heat.

My max engine temp is 230* as well with the boiling point of my system at 250* on a 13lb radiator cap.

Here is a chart I like to help me keeps things honest.