The Ram has a new feature to me, it has a transmission temperature display. Towing our travel trailer, I was a little surprised that the change in ATF temperature was very little, maybe 210 if it was going up a hill, but even without towing it usually hangs around 200 degrees. That got me thinking, what condition would keep the ATF coolest? Going up a hill at a lower RPM in higher gear, or going up a hill in higher gear? As near as I can tell, the tow/haul mode usually keeps the torque converter locked.
ATF cooling question
- Thread starter Dave Sherman
- Start date
Whatever gear keeps the most parts in the transmission spinning the slowest, and the least amount of torque from the engine going through it.
That's the best I can come up with. Your ZF8 is so complex that I can't keep track of what is spinning in what gear. Maybe if there is a 1:1 ratio that would be the least amount of heat generated.
Just a WAG on my part. There's a lot going on in there:
That's the best I can come up with. Your ZF8 is so complex that I can't keep track of what is spinning in what gear. Maybe if there is a 1:1 ratio that would be the least amount of heat generated.
Just a WAG on my part. There's a lot going on in there:
6th is direct 1:1 on the ZF-8. In my Durango, the faster you spin the trans input shaft, the hotter it gets.
Aftermarket transmission-temp gauges used to be encouraged for vehicles that were towing. The performance outfits such as Jegs and Summit probably still offer them. Use during towing is probably the reason the factory installed one on your truck. You probably don't need to monitor the transmission temperature too closely when you're not pulling a trailer or hauling a heavy load.
The danger point from online sources seems to be an ATF temperature above 225° F, but check your owner's manual. Also, does the factory gauge indicate a red danger zone? If so, at what temp?
The danger point from online sources seems to be an ATF temperature above 225° F, but check your owner's manual. Also, does the factory gauge indicate a red danger zone? If so, at what temp?
I wouldn't be concerned until you start getting up past 240. Transmissions these days (Some of them at least) run way hotter than they did in the past. Fluids have been engineered to handle this.
It is ZF8, and nothing comes close to it. Do not worry.
If the converter is locked, the trans isn't making much heat. That's the beauty of having so much ratio coverage in these new transmissions.
Ahh...a steady horsepower is needed for a steady speed up a constant grade, so--the horsepower formula is (torque lbs-ft x rpm) ÷ 5252 = hp. With the steady hp needed then if the rpm is increased the torque decreases. (5252 is the constant for our Imperial system; a different constant is used for metric units.) In other words shift out of overdrive or downshift one gear to lighten the torque on the rotating parts.
