C4 trans temp

Just wondering if my temp is o.k.-68 bronco 427 windsor and 35" tires, in rad. trans cooler and hayden big dawg trans cooler with E. fan, gets up to 210-215 f. even on little hills or very small grades it shoots up to 210, stays there and cools off when I level off and is not slipping. also stock converter. trans is pretty new by a very reputable builder.

Where is the sender located?

The C4 will have its longest life at or below 170F. At 210F the C4 will only last 1/4 of its expected life. You need to get more air through the cooler or add another cooler with a fan on it between the cooler you have and the rear line of the C4 for the longest life.

Not to conflict with what Paul said above me. But I recently put a temp gauge inline on my ranchero. I rebuilt the c4 years ago and only recently installed the temp gauge. It commonly reads 195-210, even on cool days.

This is a mild ranchero with a 302 and stock radiator (extra core added). Cooler in tank only. It might shorten the life, but I can say that mine's been running these temps for years without any adverse effects.

175-190 is a better anbd longer life temp. But sender location will make a diff on what temp you're seeing. Pan temp is after it's run thru the trans. If pan temp is 200 or less, good. If cooler outlet side is 210+, bad. Deeper pan and bigger cooler with maybe it's own cooling fan temp controled.

Good point, Dacofa. My temp sensor is on the line coming out of the trans, before the cooler. So, it's seeing the highest temp.

Yep, it's on the outlet side of the trans cooler line tee'd in at the inlet side of the rad. trans cooler. I just changed gears from 3.50s to 4.11s and it seems to run cooler but I havent taken it up any grades yet.

If possible I'd put one in the pan and one at the cooler outlet. I know it can be a hasle, put it will tell you if the cooler is big enough and working. Sometimes just a different location will make the difference.
You also don't want it to cold either. The metals and seals will not like that at all. Cold rubber seals will leak and break. That is what happened to the Space Shuttled Challenger when it blew up. The seals were cold and already cracked and brittle. When the extra pressure hit them, that was it. And did you also know that 3 of the Astronauts had water in their lungs. Because they were alive when the capsule hit the water. And one was tangled up in his safety straps.