I am running the 3:73's with 35 inch tires. On the highway around 70 mph, I am seeing temps pushing the 200 mark even with a cooler installed The hottest I can get it offroad on a nasty slow muddy, rocky uphill is about 160.. I am hoping to do the 5:13's soon. Just a word of warning for the guys running big tires and stock gears who don't have a temp gauge. If it wasn't for the temps, I'd be fine with the gearing..

 

At 70, is that with O/D on, or off?

 

tried running it both ways, doesn't seem to make a difference.

 

What are your rpms at? I dont have a cooler or a guage but i reprogramed the shift points so with the stock 3.73s at 70 mph im only at 2500 rpm with over drive off with o/d on im at 1700

 

Ummm....is 200 degrees bad? I've been driving my jk for nearly 2.5 years with 35's and an auto trans. Lot of no problem miles!

 

What kind of trany temp gauge do you have?

 

"conventional wisdom" says that ATF will last 100k miles at 175 degrees; every increase of 20 deg. cuts the lifetime in half. e.g. at 195 you get 50k miles; at 215 its good for 25k.

Is that true for every brand ATF etc. etc.? beats me.

I have an aeroforce interceptor gauge which plugs into the OBD port. One of the functions is tranny temp.

Before adding an aux cooler I would see temps as high as 195 deg just driving in the city stop/go traffic. No extra weight, just a stock 2-dr Rubi.

Since adding the cooler I have yet to go over 165 deg, even climbing long steep mountains.

 

Now, this is what I can't figure out. Why is there such a wide range of temps seen by peoples' Jeeps, similarly equipped, under similar conditions?
When I drive as described by Jiblet above, my tranny temp is in the 115 to 130 range, even on a hot day. I don't have an aux cooler, either.

 

how big is the cooler?, is it out front? and are you still using the stock one in series?

 

the cooler is the B&M that a lot of people on the board are running. it is installed as per the write up here on the site. Yes it is right in front of the condenser. should be interesting to see what difference the gearing makes.
I am running the aeroforce interceptor gauge...