I guess I'm just stupid.  Our Heap has an AOD and an aluminum rad (20", two row) with the typical trans cooling built in.   That's all.  No extra cooler.  We have managed to put about 30K on it since I rebuilt the trans and I know we drive our classic  more than most.  So, it has taken me about 12 years to amass 30k and the trans seems to be working just fine, it will likely take another 12 years to get to 60k and considering the way the trans is used I'll bet it makes it without additional cooling.  Now, I may not make it but I'm confident the trans will so why mess around with an additional cooler for a street/highway car.  It just adds more potential leak sources.
IMO

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Gaba,
when i rebuilt my truck trans, I installed a cooler because I used the beast to tow a car hauler trailer.  pretty sure you aren't going to do that with the 'stang so, keep it simple and install the lines w/o a cooler....seems unnecessary for your application.  Of course, if you plan to join the ranks of the DFW metroplex Street Outlaws, then a cooler is in order.........

josh-kebob wrote:

Gaba,
when i rebuilt my truck trans, I installed a cooler because I used the beast to tow a car hauler trailer.  pretty sure you aren't going to do that with the 'stang so, keep it simple and install the lines w/o a cooler....seems unnecessary for your application.  Of course, if you plan to join the ranks of the DFW metroplex Street Outlaws, then a cooler is in order.........

 
Hahaha!!!! That’s funny .. I have got to do that .. join their list!!! With just 1/10th HP ... I can outdrive them I’m pretty sure LMAO
Probably take 5 miles to beat them.. but hey..! Lol

The things that heat up transmission fluid are high load (towing), cruising speed above the converter's stall speed (constant slip), and constant high RPM highway use (like without an overdrive gear).  Literally your application checks none of the boxes, so I see no reason why you need an additional external cooler. 

As stated, you can overcool the fluid.  Like any oil it works best at a certain temperature, probably right in the 190-200 degree range.  Cooler than that and its too thick to flow properly, and it may also have adverse affects on the additive package in the fluid as well. 

Gaba, Re:  Your question about the 20 vs 17" rad.
IMO if the rad is keeping your engine at the normal operating temp...180 to 195 for most applications...it will also keep the trans oil cool enough.  The lower hose on my 20" at normal engine temp of 195 will read 145 on the IR temp gun.  I suspect your 17" rad will be about the same.  The 20" rad provides more cooling capacity when things get rough...like Las Vegas at 120 ambient with the AC on.  In that case it will hold the engine temp down better.

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Last edited by Bullet Bob (1/24/2019 1:38 PM)

MS wrote:

Tranny cooler goes in the lower tank of the radiator.

:facepalm