Use your cruise control or overdrive while towing?


    By Russ and Tiña De Maris


    When towing a travel trailer, can you use the cruise control? What about an overdrive transmission? These are questions that can puzzle new RVers — and even some veterans.

    First, cruise control. Here’s a school of thought where most folks who’ve had cruise tend to agree: Towing a trailer with cruise control is fine — with certain caveats. Towing “on the flat” is a snap, and may save you fuel if your cruise control handles the accelerator. However, if you encounter a situation where your transmission begins to “hunt,” that is, to move from one gear to another and back, then you may need to make a change. Usually the “hunting” can be stopped by simply slowing down or speeding up just a tad. If this settles the transmission down, well and good. If not, you may be back to “flying manually.”

    Cruise on hills can be a different story. We’ve found by our own experience that leaving the cruise control engaged when hill climbing is OK when the grade isn’t real steep. On steeper grades the cruise will try to maintain speed, downshifting and eating more fuel. If you have a fuel economy gauge in your rig, try using the cruise while hill climbing and see what happens to consumption. We often tow up hills with the cruise “off” and holding the accelerator at a given point — this means slowing down, of course, and downshifting where needed, but it pays at the pump.

    On the downhill side, safety is the chief concern. Cruise control won’t hold your speed from going “over” the set-point, so on a steep downgrade we feel more comfortable with the cruise off.

    Other places to forgo the comfort of cruise control include icy or otherwise slick roads, and in heavy traffic. We’ve found some bridge decks set up an awful “bounce” for our truck-and-trailer combination that’s enough to rattle your teeth out. Drop off the speed control and slow down to get these nasty bounces under control.

    For automatic transmission users, what about overdrive while towing? There were some trucks produced in the past that decidedly recommended against towing in overdrive. This is because by the design of these transmissions overheating could be a problem. Towing adds a heat load, and to keep the transmission cool, fluid is pumped through a radiator-like device to cool it off. In overdrive, some transmissions couldn’t pump it fast enough to handle the added heat load, and the results could be really expensive.

    First rule: Read your rig’s owner’s manual. If the manual rules out towing in overdrive, then lock out the overdrive. If the manual allows towing in overdrive, you could be conservative and safe by installing a transmission temperature gauge and keeping a close eye on it.

    Finally, you may have a rig with a “Tow/Haul” switch. For many transmissions, that switch resets the shift points of your transmission to a selection more appropriate for the extra transmission load. It may also lock up the torque converter (reducing heat buildup), and may even lock out overdrive. Again, check your owner’s manual to be safe.

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