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Now that the other tranny is together I’m wondering about my 33 hotrod with and LS3 and built Gearstar 4L65e tranny in it.
The tranny cooling line go to the lower connection on the radiator, from there it goes to a small 6x9” tranny cooler that came off a junkyard Suburban, and then back to the tranny. The 6x9” cooling coil has a fan on it.
The Gearstar tranny came with a 9 x 11” Hayden tranny cooler that isn’t connected. I was thinking about removing the connection at the bottom of the radiator and using the Hayden cooler in its pace. It would be mounted just behind the grill.
If I do this it would take longer for the tranny to heat up but it would probably run cooler.
It it worth doing this or am I dreaming?
Over cooling from most standpoints and places if near impossible. However one downside does exist. when the trans heats and cools a considerable amount is air is expelled and pulled back in the trans as the oil has a pretty high expansion rate with temp.( If you have ever sat a converter that seemed empty on the floor on a cold day then summer comes and get hot well big mess ) But the down side is if the vehicle is only driven short times and does not reach 160 or higher and you are in a humid area. Condensation same as with an engine can be a problem, They can under the right circumstance lead to internal Rust, clutch or band delamination.
In my own car I run a small stand alone cooler with a small fan controlled by a coolant line inserted 165 degree thermal switch here in PA. My trans temp monitored stays around 160 after 5 or more miles driving but of course my car is driven daily . The fan rarely comes on . I have the thermal switch inline after the cooler. This in car driven mostly in and around town with a 2800 stall and 3.08 gears.
But the possible moisture accumulation would be by only worry of overcooling if vehicle driven sparingly and sits alot . Otherwise to me the cooler the better. Cooler oil logically does a better job of keeping frictions and steels during shifts . Even with the firmest of shifts at WOT 700hp trust me a whole lot of heat making rubbing slip during apply makes considerable heat .
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
The 40k transmission oil cooler a few here have suggested to me works great. I went through the trouble of installing a smaller fan blown cooler in one of my trucks and wish I would have just gone with the passive 40k.
Thanks for the info guys.
I do drive the hotrod in cooler weather but not that much. The humidity here in the high desert is almost never above 30%, typically in the 10-20% range.
My concern was the summer heat, 95-102ºF.
Maybe I should let the tranny fluid go thru the radiator, then thru the Hayden stacked plate cooler and then thru the smaller cooler that has a fan on it.
This is the Hayden I have. https://www.haydenauto.com/en/ecatal...0Cooler&type=p
You can DEFINITELY "Over-Cool" transmission fluid.
My initial 4L80 installation routed fluid through Tru-Cool 40K and directly back to Transmission.
Transmission temps would range from 30 to 75 degrees F, never reaching operating temperature.
I have since re-routed transmission lines so that fluid first goes through Tru-Cool, then goes through the heat exchange coil in the radiator to WARM UP the fluid properly, and then returns to radiator.
Cold fluid temperature inhibits torque converter lock up, and is not good for long term transmission service life.
You can DEFINITELY "Over-Cool" transmission fluid.
My initial 4L80 installation routed fluid through Tru-Cool 40K and directly back to Transmission.
Transmission temps would range from 30 to 75 degrees F, never reaching operating temperature.
I have since re-routed transmission lines so that fluid first goes through Tru-Cool, then goes through the heat exchange coil in the radiator to WARM UP the fluid properly, and then returns to radiator.
Cold fluid temperature inhibits torque converter lock up, and is not good for long term transmission service life.
You're in Alaska...I can see there could be an issue...OP's in New Mexico. You two are at each end of the spectrum.
Thanks for the kind words.
I used the same trans cooler on my 68 C10 LS6/4L60E swap. Not a great pic but you can just see the cooler in the front of the radiator.
I think the other benny is that when radiator cooling fan kick in it pulls air thru the radiator and the trans cooler.
One thing to remember is that long cooler lines and big cooler can raise
converter internal pressures a lot. I'm thinking or high stall race stuff though guess.
Also, the failed rear main thrust can be caused and traced to such things.
BTW, Many OEM's Use trans cooler bypass units to warm the oil up quickly to
reduce wear and save gas.
One thing to remember is that long cooler lines and big cooler can raise
converter internal pressures a lot. I'm thinking or high stall race stuff though guess.
Also, the failed rear main thrust can be caused and traced to such things.
BTW, Many OEM's Use trans cooler bypass units to warm the oil up quickly to
reduce wear and save gas.
Yes I have expressed concerns about larger coolers and long line runs over this issue or multiple coolers. My preference is a smaller cooler with a thermostatically operated fan in my case 180f turn on .
In my own car even with less than ideal air flow placement the small cooler with a 2800 stall in town driving is pretty adequate as the fan comes on rarely and only of pretty hot days usually for short periods of time, I have an LED in my car that lets me know its on. And monitoring data trans temps rarely get to more that 160f and can actually drop on the highway 4th gear locked to very near ambient temps .
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
I would suggest not running the trans cooler through an OEM radiator, which for e.g. a 1998 Camaro is now 27 years old. There have been several reports of the trans cooling line rusting/failing in the old OEM radiator which leads to complete trans failure as it fills with radiator fluid.
Sorry to respectfully disagree with post #13, about running the trans cooling line through the radiator after an external cooler. This will likely cause the fluid to actually warm up to e.g. 210F which is higher than the optimum 150F (or so) trans temperature. Of course needs in extremely cold climates are different than for most of us.
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Transmission Cooling? 
