Definitely go with Eric's (88grandmarq) advice. He is da' MAN for this transmission.

I would definitely still use the factory cooler in addition to the one you are adding. I run a 1996 CV in 24 hours of Lemons and Luckydog, we have a medium sized cooler plumbed inline with the factory cooler.

Our factory 4r70w got as hot as yours and wore out the 2nd and 3rd gear clutches. It did have atleast 168,000 miles but the heat killed it.

I run my aux cooler in series with the OEM cooler in the return line to the transmission, it's mounted in front of the radiator hanging from the cross bar with two "steadies" attached to lower core support, it gets air that comes in from under the bumper.

Every instruction set I've read from a bunch of cooler and transmission vendors says to do it this way.

I actually had a long discussion with Eric today, super helpful and very knowledgable guys. (Also really nice.) We talked about every thing from Trans Temps, to drive shaft speed, rear gearing, and even a little suspension.

After some discussion, here is the current plan.

1) We are actually going to ditch the OEM cooler and run this monster. (https://derale.com/product-footer/fluid-...54/13504-detail)

The logic here is we are located on the west coast, and most of the races are in the summer months. IF (and I doubt this) we can't get the trans up to operating temp, we'll pull the old NASCAR trick of blocking off part of the cooler.
2) We're making the switch to Amsoil Mercon V.
3) J-Mod and Valve body rebuild with Eric's special touches.

That's the plan for now, I'll post some pics when it's all in, and report back after the race.

Thank you to all of you for your input, and help.

I'm surprised nobody mentioned the deep aluminum LPW transmission pan that has cooling fins and allows it to hold 2 additional quarts of oil and has an oil drain plug.

In older threads it was recommended by 88grandmarq because of the pegs inside of the pan that allow it to support the transmission filter. I'm getting one in the next week or so and it would be interesting to see the temperature difference by switching to this pan.

https://www.jegs.com/i/LPW/619/501-AOD/10002/-1

https://www.lpwracing.com/Trans_Pans/Deep_Transmission_Pans.html

Great suggestion. The only concern we have about that pan is it hangs below the cross member. We're okay now at stock height, but we will soon be MUCH lower, and I feel like there is a good chance we would snag that on the curbing at the track.

I don't know how much benefit you'd get from a deep pan in a 24-hour race. The fluid will come up to temp slower because there's more of it, which would help for the first hour or so. But adding a big enough cooler also increases fluid capacity and will throw off a lot more heat than a finned pan.

I did mention it .. read point 3 in my original reply.

Or one could plumb a nice aluminum or other durable gallon or so tank in line kind of like those Moon tanks, in up high, out down low.

Buddy had a '67 Mustang with a 427TP he raced, drove on the street some, did that with the coolant, the increased volume helped he said.

Does anyone know how to keep a magnet inside a aluminum transmission pan without glue/jb weld? Will a magnetic drain plug be sufficient?

Assuming your transmission doesn't generate an abnormal amount of wear metals, and you do a drain & fill at reasonable intervals, the magnetic plug should be fine. If you're concerned, you could also use a Magnefine filter in the cooler line. Be sure to check the cooler line size...I *think* they're 5/16".