Now that you are going to tow!

By Brian Klaubert

Atlanta has just seen the annual Boat Show and the Camping/RV show. Some reading this probably bought something at these shows, and many others already have boats or trailers. This, coupled with several transmission replacements we have done recently, has motivated me to explain a few things about towing a trailer.

Any time you tow a trailer you should stay out of overdrive. Overdrive is great for driving your vehicle at highway speeds under normal loads – like you, the kids and a dog. When you tow a trailer you add not only weight but a considerable amount of wind resistance. Even an empty trailer significantly increases the amount of work done by the transmission.

Overdrive allows your engine to run more fuel efficiently under typical conditions, but it increases the load the transmission bears. With increased load, the transmission will also have to downshift much more frequently. The engine RPM will be much higher when you drive without overdrive. It will sound very different, but do not worry, it isn’t hurting the engine.

The number one enemy of your transmission is heat. Your transmission generates heat moving your car or truck forward. Your cooling system is supposed to get rid of this heat. The number two enemy of your transmission is wear. Wear increases with shifting under a heavy load. The transmission fluid provides lubrication to minimize wear and transfers the heat from the transmission to the cooling system.

Every car today has a transmission cooler in the main radiator. This is sufficient for normal vehicle loads. However, if you tow a trailer, even only occasionally, you should absolutely have an auxiliary transmission oil cooler. This is a mini size radiator just for the transmission fluid. It is mounted up by the main radiator and air conditioning coil behind the grill. Any vehicle with a factory towing package already has an auxiliary transmission cooler. Some vehicles not equipped for towing have an auxiliary cooler also.

Lastly, when you tow a trailer you should replace the fluids in the transmission, transfer case, and differential much more frequently. The extra heat of towing oxidizes the fluids and removes the special additives of the fluids. This means that they do not lubricate as well as they need to. Vehicles driven with worn out fluids will need major drivetrain repairs.

Ironically, I am now at the point that I first wanted to write about. What to look for in an ideal tow vehicle. If you tow a very big boat or trailer, you should strongly consider buying the ¾ ton variety of pick-up or SUV. These are the 250 or 2500 series of trucks. This series of truck is engineered for much more load and many more miles. The transmission and differential on these vehicles is bigger. This means it both generates less heat and can handle more load. Don’t look at the identical engine size on a 150 or 1500 series truck and assume it is the same drivetrain as the 250/2500 series. We work on a lot of commercial trucks and can tell you there is a significant difference in the load and mileage the larger series can handle without expensive repairs. Happy towing!

Brian Klaubert owns Christian Brothers Automotive-Hamilton Mill, on Braselton Hwy in Dacula. (770) 271-4080