The Top Six Reasons For Upgrading To Our IRS and 4-Link Rear Suspensions Systems

Obadiah Elliot is credited as the father of the “modern” leaf spring with his 1804 patent on elliptical versions of the simplistic suspension design, but the history of this archaic technology goes back even further, with leaf springs first appearing on carriages in the mid-17th century. Yes, that is right. The rear suspension technology on your Dodge Challenger or Plymouth Barracuda is centuries old. So why did Mopar fit these American muscle car icons with “buggy suspension” more likely to be found on a horse-drawn carriage than a modern vehicle? Because leaf springs are easy to mass produce, simple to design and cheap.

The good news is that you don’t have to be stuck with outdated suspension when building your 1970-74 Dodge Challenger or Plymouth Barracuda. Our Heidts BOLT IN PRO-G IRS and 4-LINK rear suspension kits modernize your Mopar by completely ditching the factory leaf springs in favor of coil springs. So why should you depart with your hard-earned cash for one of our systems? Let’s look at our top six reasons to upgrade to a Heidts IRS or 4-LINK kit.

A Way Better Ride

The pioneers of the Wild West were hearty people. They had to be as they constantly got their teeth knocked out bouncing across inhospitable terrain in leaf-sprung wagons. Leaf springs are designed to carry weight and not necessarily with ride quality in mind. Overcoming the multiple leaves compromising the spring takes a fair amount of input. And leaf springs tend to release that inputted energy more violently, causing excess rebound and pogoing. All of it adds up to a much rougher ride compared to coil springs that don’t share those characteristics and absorb road imperfections more easily.

Improved Handling

Are there any modern sports cars that use leaf springs? The answer is no, with only the Chevy Corvette somehow still using a transversely-mounted leaf spring until 2019. Every other serious sports car ditched leaf springs long ago because the suspension design doesn’t corner well. Hitting a corner mid-bump or chatter at the limits of adhesion can dramatically upset a leaf-sprung car or put it in a ditch. Getting rid of leaf springs with our 4-LINK kit allows for your Dodge Challenger or Plymouth Barracuda to absorb bumps and grip the road better. Our BOLT IN PRO-G IRS kit offers the ultimate in handling as the rear suspension can now move independently for better bump compliance. And, unlike with solid axles, the toe and camber are also adjustable.

Eliminates Wheel Hop

Wheel hop is just plain nasty, but common to almost any leaf-sprung rear suspension. Mash the gas pedal and leaf springs allow the axle housing to twist under the forces of acceleration. The rapid rebound of leaf springs then pushes back against that twist. Instead of accelerating, your rear axle hops up and down, causing a massive loss of grip. And the more horsepower you add, the worse it gets. Our four-link kit completely eliminates wheel hop as the axle is secured by links and can’t twist. With our IRS kit, there is no rear axle to twist, making wheel hop a thing of the past. With either in place, the result is more grip and dramatically improved acceleration.

Completely Reversible

We get it. A classic Barracuda or Challenger is a dream car for most of us. Hacking into and permanently altering it can be an extremely scary idea. Thankfully, you don’t have to do either with our four-link or IRS kits. Both are designed to bolt into place without the need for irreversible modifications to your prized possession. They also come complete with everything needed to simplify the installation process. You don’t have to figure anything out or worry about “MacGyvering” the install; we have already done all the homework and engineering for you. Whether you or a shop performs the work, the result is a clean installation that can be returned to stock if desired.

Stronger and Better Than Stock

Our Heidts 4-LINK rear suspension kit is designed to work with the stock Dana rear axle housing. We offer a fabricated Ford 9-inch rear axle housing and Currie TwinTrac limited-slip differential third member. Our BOLT IN PRO-G IRS kit is also extremely stout with 33-spline CV shafts that can handle up to 800 horsepower. The shafts attach to a fabricated Ford 9-inch center section with a Currie TwinTrac third member available as an option. Both of our kits allow for more strength and a massive upgrade in stopping power over the factory drums with multiple Wilwood caliper and rotor combinations available. Not only are you significantly upgrading the ride, handling and braking ability of your Challenger or Barracuda, but also its strength.

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