Ideal Transmisson Temp

[JohnJohn]

98, 130k, AW4, 35s, 4.56s, 10"x12" aux cooler mounted to the driver side front of the radiator, tranny temp gauge installed on the cool line.

- At what temp should I start to worry?
- As a general rule, what tmp was the fluid before it was cooled?

Thanks,

[8Mud]

I always thought 180 was the ideal temp. for most lubricants, guess it`s a leftover from my motorcycle days. 180 was always the magic number.
Read a prospect for a tranny cooler the other day, said, tranny fluid starts to break down fast above 170. Didn´t make much sense to me, figure at the pump or right at the clutches, it was getting a whole lot hotter than that, during normal operation.
Used to watch my Chev., when the tranny was heating up (had a sender in the deep pan), it would also heat up the motor (coolant) even with a rather large tranny cooler, kind of a slippery slope, the motor and the tranny would heat up together and get to around 240 pretty quick, tranny fluid usually smelled burnt afterwords. I had the in radiator cooler and the aux cooler both hooked up. Took a fried tranny apart, much of the internals was burnt black and blue, I´d say it was well above 170F.
My XJ with the stock aux. cooler, doesn´t seem to heat up the tranny often.

[JohnJohn]

Interesting. The cool side gets up to 180 at times, sometimes over that while driving on side streets. Guess that means the hot side is 20+ degrees hotter than that???