I do agree with that and thanks to members like you that help other members like me to learn and check thins out. Thats is why I'm getting a gauge to see where my trans is running. Better safe than sorry. And a temp gauge is not that much.

 

I installed a B & M tranny cooler on my TH350 before switching to a 5 speed. The tranny ran cooler and shifter better with it. I don't believe any auto tranny has any problems reaching 150 plus degrees under ordinary driving conditions. The tranny cooler let the engine operate a little cooler as well. Just my experience with this subject. The 5 speed manual eliminated a lot of the cooling issues and is a great mod to do.
Bernie

 

BTO voided my warranty on a 700r4 level 3 that blew in less than a week because of running the external only cooler. I had installed a TCI temp guage and can assure you the temps never got over 150,even in 95 degree heat.

I have since swapped to a Rossler th400 with a full manual reverse VB, 3000 stall, beat it regularly and still run the same external cooler only.(It's a Summit 17"x10" cooler)

 

I wouldn't worry about your tranny running to cool. I have a Hugh's TH350 with a 2800 stall and run a separate trans oil cooler mounted under the pass seat with a 10" fan mounted to it controlled with a T-stat set at around 160*. My fan will come on with the car sitting there idling for about 8 to 10 minutes and than cycle off.

Neal

 

Just want to share about 30 years of experience on this trans cooler issue. First, many sources say not to run the trans fluid too cool. I do not subscribe to this theory for two reasons: one as stated above in other threads, running the trans fluid through the radiator is primarily for heating up the fluid in very cold temperatures and the stock system through the radiator is far from optimal in high temperatures. Transmission fluid can get VERY hot in stop and go traffic. Two: Again as stated above, I would not worry about the fluid running too cool with an external only cooler. I say this for a number of reasons. I had a 1973 Nova SS with the turbo 350 with 2 external trans coolers doing all the cooling duty. I ran this car for 168,000 miles (BTW, I beat the crap out of that transmission as a kid) with the original tranny with zero issues when I sold it. This car also ran in very cold temperatures, down to 0 and below. The only issue was that in very cold temperatures below 10 degrees it shifted slow until a few miles were driven. I changed the fluid and filter every 25,000 miles. I currently have run on my 1994 Mustang GT an external only Long 28,000 GVW double stacked plate cooler ( not a tube and fin which are much less efficient) for the automatic. I by passed the radiator on the mustang for the same reason on the Nova to let the radiator cool the engine only. I took it out yesterday in 40 degree weather for some exercise and it does take a bit to heat up. I don't drive the mustang much especially in cold weather so it is a non issue as long as I take it easy for the first few miles. When I returned from my 20 mile trip the trans was warm, not hot. In the summer, the cooler will get hot but not like running the lines through the radiator, much less so. The Mobil 1 Trans fluid is perfect at every change, no sludge, color still good, everything perfect. I have had that setup for 11 years!. Lastly, on my 2001 Pontiac Grand Prix, I have a 18,000 GVW Long cooler AFTER the radiator, not external only, since this car is driven dailey in all conditions, including the bitter cold in New England. On this car, I wanted the radiator to heat the fluid quickly and then it is cooled by the double stack cooler after it leaves the radiator and before going back to the transmission. I use Mobil 1 synthetic as well in this car and the trans has 100,000 miles on it. Since the 4T65E tranny in the grand prix is electronically governed I wanted to make sure that the fluid gets over 77 degrees which is the bottom limit for torque converter lockup. Lastly, a friend with an Allison Diesel in his pickup, totally stock, no additional coolers from the factory runs 115 degrees trans temperature all day long on the highway. So much for the theory of running too cool!

Bottom line: If I had a corvette with an automatic (which I don't, mine is a 4 speed), I would run the biggest double stack cooler you can fit in the grill external to the radiator, use a quality synthetic trans fluid (like Mobil 1, thinking about Dexron VI for the Grand Prix), and change the fluid and filter often (every 2 years if driven often and it hot climates or every 3 years if driven infrequently.

Hope my experiences are helpful to you!