Rebel wrote:But even though the transmission temperature gauge doesn't get over 100F, the shifting becomes normal after a few blocks of driving.
Is this still the case Rob and this is running aux. cooler only,,correct ??
No, I'm presently running the aftermarket cooler plumbed in before the radiator. When I first installed the cooler, I had it running alone; I didn't plumb in the radiator. This was with the first transmission I had in my 89 and it had slippage problems. I had installed a transmission temperature gauge and freaked out when I saw how hot the ATF was getting--the gauge was pegged at max after a little in-town driving on a hot day. I immediately added the transmission cooler. I bought one for an RV, the biggest cooler I could find. Like I mentioned, I originally just had the transmission connected to it, no path through the radiator at all. That really helped, at least the temperature gauge was pegged, but it was close. So I then added the radiator back into the ATF circuit in the form of transmission--aux cooler--radiator cooler--back to transmission. That got the temperatures down some more, at least I wasn't scared anymore to look at the temperature gauge.
But the real answer was to install a better functioning transmission, which I did. I left the cooler plumbing as I had it for the old transmission. With the rebuilt transmission, I rarely ever see the transmission temperature go above 165F in the summer. But, when I installed the transmission, I also added a B&M deep transmission pan that adds an extra 3 quarts of ATF. Extra capacity has got to help some when it comes to temperatures, but I don't know how much. So I have to think that the aux cooler is what's really doing the job.
I'm not done experimenting with cooling the transmission yet. I still want to see how the transmission does without the radiator in the circuit; I just don't think that the radiator should have to deal with the heat from the transmission. No science to back that up, though, just a personal preference.
By the way, when I initially installed the transmission temperature gauge I used two sensors; one was teed into the output transmission line while the other was teed into the input line. I used a SPDT toggle switch to select which sensor the gauge was connected to. My intention was to see just how much heat was getting dumped by the cooler. It was a good idea, but almost immediately one of the sensors failed (don't remember which one) and caused the gauge to read maximum temperature. I didn't feel like coughing up the bucks for another sensor, so I just deleted it from the plumbing. Someday, I'll get another sensor and connect it all back up again.
If I recall correctly, Darren does have two sensors monitoring the temperature drop across the transmission coolers in his van.