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Hello,

I've got the factory transmission cooler in the radiator, and an aftermarket Hayden cooler. The fluid goes to the factory one first, exits, then into the aftermarket one, and back into the transmission.

I have thermistors that I can attach to the pipes to monitor the trans fluid temp. Where is the best place I should be measuring at, Outlet Tube of the Transmission going to the coolers.... or return tube returning to the trans after the coolers?

What Transmission fluid temp Should I not let the ATF exceed, e.g what point begins being slightly dangerous.

Thanks.
 

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You have to measure the transmission fluid after it gets done with its 'work' of lubricating the transmission. That is either the pan or the outlet to the cooler. As far as using thermistors, my experience with them is generally poor and now am using a temperature sender in the pan. While it may not be reading the last possible degree of temperature, it will be within a few degrees.

the guideline I use - sorry, you have to convert to deg C:
 

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I would think that if you are worried about how hot the fluid is getting, you would measure the fluid at the hottest point. Before any coolers, and as close to the transmission as possible.
 

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Almost looks like Malc and I shared ideas with the temp sender. My trans runs at 180F, approximately the same as the engine:



My cooler arrangement isn't quite as elaborate, but with a 2300 pound car, not needed where I live:



I should have posted these photos earlier, but it was just too early to 'think'

Dave W
 

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I would think that if you are worried about how hot the fluid is getting, you would measure the fluid at the hottest point. Before any coolers, and as close to the transmission as possible.
The line Out/Feed to cooler comes straight out of the TC/TorqueConverter, it will be much hotter than the fluid circulating thru the trans. Trans pan or line In/Return from cooler are best locations.
 

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The "cooler" in factory radiators is in fact a warmer upper, to get the trans in everyday drivers up to operating temp quicker.
Although I control my TH700R4 trans fluid with the thermostat it takes forever to get to 180º an ideal temp, which will burn off contaminants in the fluid.

Same applies to the oil in the motor, but that is helped to temp by the combustion process.
 
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