by KCStudly » Mon Sep 26, 2016 7:50 am
Most OEM's actually recommend turning off the overdrive while towing, and along with it the lockup feature in the torque converter. The TC lockup clutch size is a design compromise and is only ever intended to be used at cruising speeds under light throttle where very little HP is being transmitted thru the drive line. Computer calibrations for engagement are based on typical vehicle dynamics, which get thrown out when towing. Except for the very lightest TD's, the extra loads will likely cause additional TC clutch slippage, more heat, and possible failure. The computer will cycle the TC clutch much more frequently with accelerations and down shifts, putting more wear and tear on it. By allowing the TC to multiply torque and the lower (non-OD) gears to assist with the extra load, you may actually be generating less heat. (Still, an aux cooler is recommended if not already included in a tow package.)
I make it a habit to switch off the overdrive even when just towing an empty UT. Your mileage may vary, of course (truth, no pun). Some people will claim that they never have a problem and tow in OD all the time. My thoughts are that it is a matter of degrees; your 200k mile transmission life expectancy may be cut dramatically short, but in 75k miles you "never had a problem".
Last edited by
KCStudly on Wed Sep 28, 2016 10:24 am, edited 1 time in total.
KC
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