Why two straight axles makes the Jeep unique

Why two straight axles makes the Jeep unique

There's a lot that makes the Jeep Wrangler unique, and much of that has to do with how it integrates the lessons of well over a half-century of military and consumer history with today's most exciting off-road technologies.

The award-winning Jeep lineup has certainly evolved and expanded over the years - in fact, North America's enthusiasm for the SUV began in the early 1980s with the debut of the 1984 Jeep Cherokee XJ crossover. But although the Jeep lineup features off-road capable vehicles of all sizes, audiences, and price points, the Jeep Wrangler looks back to the all-terrain wartime origins of Jeep like nothing else. And a key part of that heritage is the Wrangler's consistent use of solid axles.

It began in 1945 with the release of the CJ-2A, the first civilian Jeep.

Based on the wartime models manufactured by both Willys-Overland and Ford, the CJ-2A married the high ground clearance, live solid axles, four-wheel-drive powertrain, and light frame of the military design with a variety of attractive consumer features. Today's Jeep Wrangler boasts standard Dana 44 front and rear solid axles - a design that dates back to the 1940s that's still in wide use today, particularly in vehicles that are intended for heavy-duty off-road use.

Why two straight axles makes the Jeep unique

But what is a straight, solid, rigid, or beam axle, and what does it do?

Well, first off, all of those terms basically mean the same thing. (Don't ask us why.)

Secondly, let's cover what straight axles are not, and where you probably won't find them. Today, most vehicles, including many in today's Jeep lineup, use independent suspension systems that allow front, back, or all four tires to move vertically independently of each other.

Despite some early fears among Wrangler diehards that the next model might abandon solid axles in favor of independent suspension, the 2016 Jeep Wrangler boasts much the same suspension philosophy as it has from the very beginning.

Solid suspension systems are known for their relative inexpensiveness to produce and maintain, high articulation, and ease of aftermarket modification.

Articulation, as measured by the RTI or ramp travel index, is a value that rates the distance that a single wheel's suspension system can flex as it travels up a (most often 20-degree) ramp. It's equal to the distance traveled before one of the other three tires lifts off the ground, divided by the wheelbase, multiplied by 1000. Wikipedia cites most SUVs as being rated from 400 to 550, while purpose-modified off-road vehicles can clear 1000.

Why two straight axles makes the Jeep unique

Although Jeep doesn't release official RTI stats for the Wrangler, Edmund's conducted an informal test on a few 2012 Wrangler models, and the stock Wrangler Sport and Wrangler Rubicon both made an excellent showing. Articulation is the key advantage of solid suspension systems - because when those three wheels are still on the ground, they're providing grip to push you over the toughest obstacles.

There's no better way to understand the value of the Jeep design tradition, including the Wrangler's commitment to solid axle design, than to take a Trail-Rated® Jeep off-road and feel the difference for yourself. Let the pros at Marine Chrysler walk you through the ins and outs of today's best new and pre-owned Jeep vehicles - and discover a used inventory that goes beyond, including selections from all major manufacturers!

Want to learn more about the history of Jeep and the significance of solid axle design? Check out some of these links for more: