Before I get blasted with the newbie crud, this is what I'm building: CJ8 with hydroboosted Dana 60's and lockers, Wrangler 2 1/2" lift springs, 38" Swampers on Hummer wheels, and a 2004 Chevy Vortec V-6 with a 4L-60E tranny and Atlas transfer case. I've fabricated and installed everything myself and I am trying to figure out the cooling system. The radiator is a slam dunk leaving the oil, transmission, and power steering cooling. I live in Phoenix, Arizona where it is damn hot but kinda cold in the winter time in some areas at least. I figure I will run the oil through a built in radiator cooler since it should all be about the same temp anyway. Now there is the the transmission and power steering. Is there an optimum temperature that they run at?? If I just throw the biggest baddest coolers on the front of the radiator, will they stay too cool in the winter time?? Bottom line is it the cooler they get the better they are or is there a minimum temperature they need to operate at?? No real way to regulate the temps specifically without a pain in the backside system of fans and thermostats. Flame away cause I already searched the hell out of this one!

quick answer-the old Type F had a problem with being too cold-Dexron type fluids do better cold.

liquid nitrogen would probably over cool it :flipoff2:

Many vehicles come stock with extra transmissions coolers up here in Canada and many of us who tow add even larget units and run these setups all year. Considering it can regularly be between 0*F and 14*F I think you'll be fine.

its called cardboard!

If its cold as hell out and your tranny isnt warming up you duct tape a piece of cardboard to the front of the cooler and its almost like it was never installed. Is it half assed... kinda but it works and if you use good tape you only have to do it once a season.

The 4L60's like to run warmer than an old th350 or th400. They usually run about 20-30 degrees cooler then engine temps. As long as it does not get above 240 degrees they are fine.

I asked the same questions a few months ago when I was putting my TBI/4L60E in my 84 CJ....some guys said "yea, you don't want it too cold", others suggested running the fluid from the external tranny cooler through the radiator tranny cooler before going back to the transmission.

Then I asked two different transmission shops. They both gave me the same answer..."BS...except for sub 0 weather, you can't run a tranny too cool". The cooler you keep it, the longer it lasts.

So...I ran my tranny cooler external....right next to the oil cooler....
http://tellico.off-road.com/wwwthreads_uploads/1463202-FanandCoolers.JPG

FYI...make sure you hook everything up right....including the brake light switch to the computer. This signal is needed to control the lock up converter. The lock up feature reduceces transmission temp by a considerable amount.