When is my Cummins the happiest?
I have a 2004.5 RAM with the 5.9L and the 4 speed automatic. I tow a 10,000# trailer for 18,000# combined. I find the transmission has awkward ratios at 55-60 MPH: At 55MPH - In drive, 1,500 RPM,...
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I tow with a 1996 Ford diesel with a 3.55 axle and have about exactly the same rpm vs speed ratio as your Dodge, and with about identical egts at those speeds.
For the past 20 years I've been towing in overdrive at the 55 to 60 mph range and have experienced no mechanical problems with either the engine nor the auto tranny.
Of course, when I get in the hills I shift it out of overdrive into third when the tranny starts "hunting," which is what Ford recommends. On long mountain grades, the gear I select is determined by my EGTs.
For the past 20 years I've been towing in overdrive at the 55 to 60 mph range and have experienced no mechanical problems with either the engine nor the auto tranny.
Of course, when I get in the hills I shift it out of overdrive into third when the tranny starts "hunting," which is what Ford recommends. On long mountain grades, the gear I select is determined by my EGTs.
