Posted by Todd Wilson on Tuesday, July 19, 2005 at 0:11AM :
In Reply to: Yeah, an answer! still not sure I understand whying posted by George in NW Michigan on Monday, July 18, 2005 at 9:41PM :
Maybe its me or are we getting OD and lock up mixed up? In the older trannys you shut off the OD which basically shut OD and lock up off?!?!
Didnt the Cummins guys wire a switch to go ahead and "Lock Up" the convertor for better pulling? While staying out of OD (4th)
You had to be careful to un lock it as you came to a stop or you would get rolled right on thru the intersection in lock up. Flipping the OD off kept the tranny from going to 4th gear AKA OD and kept the convertor from locking up. Locking up the convertor isnt the problem. Pulling heavy loads creates more heat in the transmission. In OD everything is turning more slowing and its not pumping tranny fluid as fast as it should and when it dont pump fast it doesnt cycle thru the cooler fast enough. Fluid heats up and gets hot. Heat will kill a auto tranny quickly.
I think the new "TOW" mode setups shut the OD off but also firm up the shifts and changes the shift points for better power to the ground. A hard shifting auto tranny is better then a nice soft shifting one when pulling loads. The soft shifting one is slipping when it shifts.
People with Cummins diesels in the past have pulled with the OD on and will burn an auto out in no time. Thats how Dodge got the bad rap for having transmission problems. People pulling in OD and all that low end tork from the diesel pulled the guts out of the tranny.
Todd
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