Originally Posted by
jbamonte
Thanks for giving a real world example with the LS4 and the 4T65E-HD tranny with a trans cooler. As stated earlier if you size the cooler (S) to the heat reduction required with a proper installation, any transmission will see a dramatic reduction in temperature regardless of the engine in front or along side the tranny. I looked up the GVW rating of your tranny cooler which is 30,000 GVW (decent size BTW) but you could easily see another 30 degree in drop in the summer by separating the tranny cooler from the in radiator cooling, and allowing the tranny cooler to do all the cooling like it does in my 3 cars. My guess is that the average coolant temp for that LS4 V8 if similar to other GM V8's like my LS7 is about 210 degrees. The reason the tranny temps are so high on stock trans radiator cooled LS4's is that the very hot tranny fluid is attempting to be cooled by coolant that is 210 degrees.....WAY TOO HIGH AND HOT. The ideal tranny temp despite what is often published is not around 180 degrees. it is around 140 degrees for all year round driving but often difficult to achieve with just 1 cooler ( I have 2 Long Dana coolers on my GP and 2 coolers on my Mustang GT as well outside of the radiator cooling...stand alones). You could easily drop another 30 degree reduction with your setup if you allow the Hayden cooler to do all the trans fluid cooling outside of the radiator.
My 01 GP has 205,000 miles on the tranny with the 2 coolers doing all the cooling outside of the radiator and I drive the car all year round in VERY cold weather. The only issue in very cold weather is that the tranny needs about 3 miles of gentle driving when below 20 degrees outside to shift in OD since the fluid takes longer to heat up under those conditions....well worth this minor delay. The Long/Dana coolers with built in temp control never let the fluid drop below 120 degrees. If you do not drive the car in the winter anymore, I certainly would have the cooler as a stand alone outside of the radiator since 180 degrees in the summer is still too high, in my opinion based on 35 years of adding coolers on my personal cars...........The number #1 killer of any transmission is HEAT followed by dirt (change the fluid/filter often @20,000 mile intervals and the 4T65E will live a long life.)
