What type of people do you meet at the Track??????

[stentech1]

It is very interesting how manufacturers have these towing capacity values put on their trucks. The fact is that none of the tow rating take into account the type A drivers that most of us are and tremendous amount of additional drag that is created when towing an enclosed trailer. A great example of this is the Titan and Armada being discussed. These transmissions are very capable well engineered units but when put under the extreme requirements of towing especially when it is an enclosed trailer they tend to get very warm. In a typical gas truck application getting the truck to go up hills at highway speeds may require the driver to put his foot into the throttle say 60%.  At that point the throttle position sensor signal is high enough for the transmission torque converter to release as commanded by the PCM (power-train control module) When the torque converter clutch is not engaged it generates a tremendous amount of heat. I have had a transmission get so hot that it boiled over the radiator towing a 4 place enclosed snowmobile trailer in the middle of winter now imagine what happens in the middle summer towing an enclosed car trailer. The load that a truck is put under at speed when towing an enclosed is tremendous. With increase in speed there is an exponential increase in aerodynamic drag. So when towing an enclosed trailer even going 10 mph faster requires a lot more power hence more throttle input and a torque converter that is not locked and generating a ton of heat. It is some times beneficial to tow a trailer in a lower gear. Many of the trucks are 5-6 speed automatics designed for fuel economy. Putting the truck in a lower gear will give the engine more of a mechanical advantage over the mass and drag of the trailer. This will result in lower tps (throttle position sensor) value which may keep the converter clutch locked up reducing heat. I have taken apart transmissions and seen converters that got so hot they turned purple like the pipes on a Harley. One major problem that the Nissan trucks we are discussing have is transmission cooler failures.  I have seen it many times over the past 3 years where the transmission heat exchanger in the radiator has failed and allowed engine coolant into the transmission. This coolant de laminated all of the friction material off the steel plates and if that is not bad enough the TCM (transmission control module) is in the fluid on top of the valve body. This also requires replacement when there is water intrusion into the transmission. The point is if you own one of these trucks eliminate the radiator heat exchanger and put a large stand alone cooler such as a tru-cool #4590 low pressure drop cooler this combined with the factory supplemental cooler will be more than enough for the truck's transmission cooling requirements.  

SM