Keep It Clean
Even the best-protected cabs need to fight corrosion
By Paul Abelson
In 1984, work was just starting on the “Tomorrow’s Truck” program at the TMC. Though now it’s the Technology and Maintenance Council, back then it was just “The Maintenance Council” of American Trucking Associations. Technology had not yet become important in trucking, but maintenance had a huge impact on operating costs.
By the early 1980s, TMC fleet members had become increasingly aware that improvements in truck design and engineering were not keeping pace with light-duty vehicles. Trucks had virtually no aerodynamic design. Fuel economy was around 4 mpg for most fleets, and owner-operators were lucky to get 3.5 mpg. Engines required overhaul after only 200,000 to 300,000 miles, and cabs needed refinishing about the same time.
Tomorrow’s Truck was the first attempt by TMC to open a dialogue with the Society of Automotive Engineers (SAE) and, through them, to truck manufacturers and major component makers. Although TMC and SAE had cooperated on developing joint fuel economy tests, that was primarily through the efforts of suppliers who belonged to both groups.
TMC members drafted a wish list of areas they wanted to see improve. High on the list were better fuel economy and greater durability. Since “stuff” happens, the truck maintenance community also wanted easier maintainability. In October 1985, nine nervous Study Group chairmen, most with years of field experience but little formal education presented their ideas about what trucks should be like to a room full of hundreds of engineers.
The response was overwhelming. Rather than making light of these laymen, the manufacturers’ experts hung on every word. Previously, they had been designing and engineering to make what they thought might sell as “new and improved.” Now they had goals that came from real needs, from real users. Truck engineering was changed forever.
Keeping cabs like new
This entire dialogue would be useless unless it translated into improved vehicles. It did, as can be seen and felt in the latest generation of trucks. Fuel mileage above 7 mpg is now common. Engines last a million miles or more. Cabs look showroom new after 10 or more years.
In the 1990s, a new villain arose: corrosive salts and chemicals used to control ice and snow. These same tools that make winter driving safer can wreak havoc on many truck components, including the cab.
Paint systems evolved as polymer chemistry improved. Low cost enamels that would last under ultraviolet sunlight for only three to four years gave way to multi-part urethane based paints and later to polyurethane and acrylic urethane base coat/clearcoat systems. They can, when properly maintained, keep their gloss for the life of the truck. That means at least yearly, and preferably more often, polishing the truck with a polish made for commercial vehicles.
It also means avoiding passenger car clear coat paint systems that do not have catalyzed base coats. They are not tough enough for commercial service. Neither are many passenger car waxes and polishes. These coatings are buffers against the ultraviolet rays that ultimately deteriorate all paints. Look for specialized protection designed for trucks.
When inspecting your truck, pay careful attention to doors, door frames and hardware. Latches and handles should operate smoothly. Hinges, linkages, support hardware and fasteners should all be free of corrosion.
Salts and chemicals are electrolytes that, when dissolved in water, form conductive paths between dissimilar metals, especially with aluminum cabs on steel chassis. Even a steel bolt can cause aluminum components to corrode if not properly isolated.
While fiberglass is not corrosive, mounting hardware is subject to corrosion. The key to maintaining long cab life is to find and break corrosive paths. Start by inspecting for corrosion. When any is found, carefully inspect metals around the area. Disassemble the parts and remove all corrosion. If it is widespread, it may require sand blasting or cutting out the damaged metal and replacing it with new metal.
Don’t just reassemble. Try to identify the corrosive path, and then take steps to break it. It may require insulated bushings or gaskets to isolate fasteners. Some coatings are applied over rust to neutralize it, but they are short-term corrections, not long-term fixes. To minimize corrosion and maximize durability, some manufacturers are turning to chemically bonding dissimilar metals, eliminating metal fasteners. When repairs are needed to bonded surfaces, they are best done by experienced professionals.
Cabs have improved dramatically since TMC’s first Tomorrow’s Truck presentation in 1985, but more aggressive highway chemicals are increasing demands on maintenance. TMC has a number of recommended practices on cab maintenance. They cover spec’ing, inspecting, selecting paint systems, preparing surfaces and even washing and cleaning guidelines. Owner-operators can get the complete RP manual, including both engineering and maintenance practices, free with a TMC membership.