TH400 operating temperature

[GranSuburban]

I recently got my TH400 rebuilt and the transmission temp gauge never gets much above 125 degrees on cool days. I've read that it should be closer to 160-180 to operate properly. What could be the cause of these low temperatures?

[BigBird05]

Running the trans oil thru the radiator is for heating and cooling the oil.

[HO455]

Welcome aboard!
If you could provide more information on how your truck is set up it would help.
Any aftermarket coolers?
Where are you checking the temperature in the system?
Have you verified the accuracy of the guage?
I believe the 160 to180 degree temperatures are for the oil in the pan.
We do like pictures around here.
Hint hint!

[GranSuburban]

It currently runs through a transmission cooler (standard hooked to radiator) and has a 1800 stall converter. The gauge is fairly new and I assume is working properly. This 125 degree operating temp was about a 15 mile drive (half of which in a wicked head wind) in about 55-60 degree ambient temperature. I feel the rebuild was done poorly, unfortunately.

[BigBird05]

The trans fluid is the last fluid to warm up in the vehicle. You might need to drive further for a valid test.

[HO455]

BigBird05 has a good point a longer drive will be more telling.
Is your guage electric? Good grounding of the sensor is important for accurate readings.

For reference TH 400's in my GTO would run about 135 degrees for the same amount of driving. That was behind a 400 with a 2500 stall converter with an aftermarket plate cooler and the radiator cooler bypassed. I have an aftermarket filter with the temperature guage sender about 18 inches after the cooler.
As far as a poor rebuild i would be more worried about temperatures above 230 degrees than low temperature. Poor assembly generally results in more friction which results in more heat.
It is odd that the temperature is 125 degrees. I am assuming the engine coolant is in the 180 to 190 degree range. Do you know if the transmission cooler component of the radiator is the factory plate style or just a loop of tubing that many aftermarket radiator manufacturers use?
Does your radiator have an overflow tank?

And on a side note what kind of wheels are those?

[GranSuburban]

The cooler is the tube style that sits in front of the radiator and cools through it. Honestly, I do not know where the sensor is. The temp gauge is the original C to H type, and it sits just above the normal temp section of the sweep.

The wheels are US Wheel Rat Rod style 66 (17x10). I have caps for the front, but the hubs are too big.

If it ever decides to warm up on my days off, I'll take it for another spin. Mother Nature hates me.

[Accelo]

The temperature is fine.
If it's over cooled that is no big deal.
Worry if it's over 200 deg F.
Drive on and enjoy.
Rick

[Dead Parrot]

What temp thermostat is in the motor? The trans cooler is on the cold end of the radiator and if the water entering the hot side is fairly cool due to a lower temp thermostat, it might not be much above ambient when it gets to the trans cooler.

As others have said, if the trans is otherwise working normally, don't worry about the cooler temps. Many folks spend a lot of money on aftermarket finned pans and stand alone coolers trying to lower their transmission temps.

[BigBird05]

Dead Parrot, If I understand correctly, He is using a aftermarket cooler so water temp would not be playing any part to the temperature.