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Tower’s Guide To Upgrading

Make plans so you won’t make mistakes

Text By Trevor Reed, Photography by The Manufacturers, Diesel Power Archives

If you need a diesel truck for towing, then you have the ability to pull tons of cargo, which means you also have the capacity to get in way over your head. Even if you don’t plan to max out your truck’s towing potential, it’s better to be safe than sorry. Here’s some advice on products that will make your towing experience less dramatic and more comfortable, both of which make towing safer for you, your family, and everyone else on the road.

High-Capacity Hitches
Most modern diesel trucks ordered with a factory tow package will include an under-bumper, or conventional, Class 4 or 5 hitch mounted to the frame, which is good for towing up to about 10,000 pounds. Even if you plan to stay within the factory guidelines, it’s always best to use a weight distribution system that places your trailer’s load evenly on the trailer ball. You’ll also need a seven-pin trailer wiring kit and a trailer brake controller if your truck is not equipped with one from the factory.

While it’s very common for drivers to surpass the bumper hitch limit, it’s a very bad idea. When you exceed the weight rating, you’re doing a lot more than ignoring a suggestion in the owner’s manual. New- vehicle engineers compute tow ratings by taking into account everything from the handling, steering, braking, and cooling, to gear strengths, bearing capacities, real-world testing, and plenty of other attributes you may not have in mind when you hook up a heavy trailer.

To properly tow a trailer that exceeds the rating of your conventional hitch, you need to step up to a gooseneck ball or fifth-wheel hitch that’s mounted between the rear framerails, directly over the rear axle. While Ford, GM, and Ram are now offering factory options for these types of hitches, you can also buy aftermarket models that offer just as much, or more capacity. Aftermarket hitches also offer plenty of additional features, including the ability to slide back to prevent the dreaded “cab crunch” where a trailer hits the truck during a sharp turn.

Transmission Toughness
Heat is one of a transmission’s most dangerous enemies—if not the most dangerous—because when parts exceed their heat limits, they are more prone to break and cause a chain-reaction disaster. While the factory heavy-duty transmissions that come with all modern diesel engines are incredible works of engineering, when they become overheated, all bets are off. So drivers who plan to tow heavy trailers must do their best to avoid excess heat and may even decide that a preventative transmission upgrade is necessary.

Two of the least expensive and most basic upgrades for a diesel transmission are the installation of a high-capacity oil pan with cooling fins, and a large auxiliary transmission fluid cooler. Another way to reduce excessive heat is by installing an aftermarket low-stall torque converter that is made with more heat-resistant materials and designed to better deal with a constant load. Drivers who know they’re going to be maxing out their towing capacity on a regular basis may want to just bite the bullet and invest in a complete transmission upgrade or replacement. Then the gearbox will be up to the task of handling extreme loads and any power upgrades that might be applied to the engine. With a new transmission, problems can be avoided and the risk of a catastrophic failure that comes at the expense of a vacation or bank account can be minimized.

Electronic Elec-Tricks
One advantage of using an electronic engine programmer is the ability to monitor multiple temperature points without the need to clutter your A-pillar or dash with numerous gauges. Of course, this is just an added bonus to the benefits of being able to reprogram your engine and transmission computers to maximize their functions while you are towing. Plus, you’ll have the ability to play with settings when your truck is not burdened with a trailer for fun on the streets, strips, or sled pulls.

Gauging Good to Prevent Breaking Bad
One of the best ways to assure you don’t break your transmission or become the victim of a different sort of major breakdown is by keeping yourself informed at all times. When it comes to towing, the most important information is the temperature of parts in your drivetrain. As discussed earlier, the transmission (especially automatics, which shouldn’t exceed 220 degrees) is particularly vulnerable to heat and should be your primary concern, but there are plenty of other parts to worry about.

With a turbodiesel under a heavy load, the EGT is also incredibly important. If you let the EGT surpass 1,200 degrees for extended periods of time, you risk the turbine wheel melting and disintegrating into your exhaust system—if you’re lucky. If you’re unlucky, excessive heat can also lead to cracked valves, blown head gaskets, and internal engine damage.

Towing also puts a lot of stress on the rear axle, so it can’t hurt to keep an eye on the temperature inside your rear differential. While maximum temperatures vary depending on the gear ratio and the weight of the trailer you are pulling, it’s probably best to keep oil in the same range as the transmission fluid. The best way to ensure your gears don’t melt and meld is to install a temperature gauge and a high-capacity differential cover with heat-dissipation fins and replace the fluid regularly. Even though it’s tempting to think of an axle as a sealed unit without the need for maintenance, it’s a lot better to prevent a failure than end up with your rear wheels locking while you are towing at highway speeds.

By Trevor Reed
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