The Great Aluminum versus Steel Truck Body Debate

What’s the Fuss?

The aluminum truck body has been in consumer hands for quite some time now and it’s time to take a look at it’s modern advantages and shortcomings compared to steel. Some companies began to manufacture truck bodies with aluminum instead of steel and since then there has been hot debate.  The ones tempted to try the aluminum bodies saw some improvements such as better gas mileage, which came from the lighter vehicle weight thanks to the aluminum panels. The main problem with the steel truck body was also eliminated by making the switch to aluminum, body rust. Steel body advocates are constantly reminding people that steel is superior for it’s strength and resilience for heavy duty applications, but the story is much deeper than that and each respective body has it’s pros and cons.

Strength

These metals by themselves come with their own reputation in our daily lives, steel composing the skeletons of skyscrapers, and being what “real” cars were made of and of course steel trucks were the status quo of truck bodies and the kings of heavy duty anyways. Aluminum on the other hand, commonly found in flimsy foil version and crushable cans, would not make a strong truck body when this logic was applied. In reality, most of the metals that compose a truck body are alloys and the aluminum bodies are no different. They are in most cases 90% aluminum or more so they are most definitely qualified as aluminum but it is the other 10% that strengthens the truck frame to handle modern situations and loads. Most steel alloys come with not only steel, but a large portion of that alloy is also made up of iron which makes for a very strong metal but iron is notorious for rust.

The strength of steel bodies is often demonstrated in unconventional ways such as dropping 1,000 lbs of bricks into a truck bed from 5 feet in the air, because everybody does that. The real strength comparisons come in crash testing where practicality and safety come into play. Surprisingly aluminum bodies outperformed steel in most crash tests.

truck body

Maintenance 

A major selling point of aluminum frames is also its resistance to rust over steel. One or two costly experiences with rusted and rotted steel parts can be enough to convince some people to give aluminum a try. Aluminum alloy truck bodies require very little maintenance outside of your standard inspection of the joints and frame. Keep in mind some fasteners on the truck could still be made of steel and are also prone to rust so keep an eye on them. Snowy and salted roads are an exception as these things will eat through any metals given enough time. Repair costs for aluminum after damage can be costly due to the tricky methods needs to reshape the aluminum. The main repair differences in the metals include the extra skills needed to shape aluminum because it doesn’t have “memory” like steel does so it is more difficult to reshape. Aluminum is also a great conductor making it more susceptible to damage during repair from excessive heating. Both of these metals are highly reactive to each other when untreated portions come in contact with each other so a completely separate workspace and set of tools is needed by a shop to even perform the repair, hence the extra repair cost for aluminum.

Steel bodies, being the most common, are well documented to rust over time and from various other factors. Steel frames require some sort of protectant to prevent the rusting body panels and joints. Most steel panels can be treated with a sealant or are painted with a rust protectant coating during manufacturing. Over time this paint cracks from stress, time and harsh road conditions and this opens up weak spots for rust to take hold in your panels. Any cracks in the paint from the flexing of the body or deep pits need to be addressed and patched to prevent the oxidation of the steel panels underneath.

steel body rust

Depending on how the steel is treated, the price of rust repairs varies drastically due to the amount of work it takes to remove and replace the rust damaged portion. There are some extra steps you can take to prevent your panels from rusting also. One option is a protectant that comes in the form of an undercoat for the truck frame, everyone seems to have a friend of a friend with a horror story about this so be cautious. Another option would be oiling the underbody by simply smearing some used oil across the weak spots every oil change. Everyone has a preference on a method or if this extra step is even needed at all but it is also something to consider.

truck body

Buckled steel truck frame

The Wrap Up

Aluminum bodies overall get a bad reputation but aren’t all that bad. Not only is the aluminum used in these bodies an alloy to make up for the short comings aluminum has on it’s own. In most cases, aluminum makes up a large portion of the truck’s body, but steel and other metals can still be used in other portions of the truck. This means that the truck frame isn’t 100% aluminum but can still be passed as an aluminum truck frame. Just as with alloys, this mix of metals allows manufacturers to make up for the downsides of just using one metal. Aluminum does in fact make for a lighter frame and in turn aluminum truck frame owners have reported better gas mileage and a smoother ride than that of a steel frame. It is a fact that aluminum costs more than steel in manufacturing but or overall repairability the cost is about the same as steel when it comes to aluminum frames once the treatment process for steel is factored in during repairs. Overall aluminum seems to have a lot of benefits with little downsides so far. Sporting lighter weight, better fuel economy and comparable strength, aluminum truck frames are on track to become more common.

truck body

Steel frames are tried and true in the truck world and have a long standing reputation as being the best metal for the job. The added strength of a steel frame also comes at the price of extra vehicle weight. A heavier vehicle translates into poorer fuel economy, slower acceleration and also takes a bite out of your total towing and hauling capacity due to the extra work the engine has to do. The constant spot checking that comes along with a steel frame could prove time consuming and if rust has a chance to take foot in your frame the repair costs skyrocket so be sure to take steps to help prevent this.

Overall each frame has its pros and cons but in the end the choice is yours. Steel has a long standing history in the industry and lots of resources and information regarding steel frames at your disposal. Aluminum is the newcomer in the industry that needs time to prove its worth in the industry. Aluminum might be the modern solution to a lot of steel’s short comings but in the end the industry will eventually decide.


Chris Abstein – Suspension Spot

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1 Comment

  1. This seems to use the words “frame” and “body” interchangeably, when those two components are usually mutually exclusive in the context of trucks.

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