Everrrrrybody’s got an opinion. Manual or Automatic. Turbo or Supercharger. Ford or Chevy. 4-Links or Radius Arms.
Despite the fact that both suspension systems work well, we still want to battle it out regarding which one is better. While we generally like to think that what we have to work with is the best option, I can’t tell you how many times I made that mistake and was left with broken equipment and egg on my face. The only way to really see what’s best is to look at the evidence. Both 4-link and radius arm setups have their benefits (as well as their drawbacks), but ultimately there is a clear winner when it comes to which is the better system. Read on to find out!
But First, What’s the Difference?
In a solid-axle vehicle, leaf springs both suspend the vehicle and control movement of the axle. Coil springs, however, can’t perform the same double-duty. This is where 4-links or radius arms come in. They locate the axle and allow it to move. Both are available on vehicles in stock form, and both can be upgraded. However, the genetics don’t change, just the dimensions, allowing them to be beefed up for better off-road performance.
For a better understanding and a second opinion, we reached out to Jeremy Naugle of Apple Hill 4X4 Auto & Collision LLC, a division of A&A Auto Stores in Muncy, PA. “Radius arms or 4-links are basically just the way the front diff or rear diff is held into the vehicle,” explains Naugle. Those arms help determine stability and control—and we don’t need to tell you how important those are out on the trail.
But to truly paint a picture of which system is better, we first need to understand how each unit works and what its limits are.
Radius arms are simple devices that clamp to the axle housing and attach to one point on the chassis. Generally made of stamped steel, these arms are located on each side of the solid axle and help maintain forward traction. “A well-known example of a radius-arm design is the early Bronco,” said Dan Guyer, Category Manager of Wheel and Tire at Keystone Automotive.
The use of two arms in this set up is to help prevent the axle housing from rotating and binding under power. One particular issue many will note with radius arms is the tendency for the front end to unload when power is applied. Now, when you’re in any vehicle, the front end will lift when power is applied. But in vehicles with radius arms suspension, this is particularly noticeable and will cause traction issues when climbing (or in any other situation when the front end is elevated). Despite the design used to prevent the axle from rotating freely, during articulation it is possible for the axle to roll, which in itself will cause issues. However, unless it’s under extreme conditions, this roll is considered negligible by many.
On the upside though, “With radius arms, they’re fixed arms. You put them on and that’s that,” says Naugle. Simple to make, simple to install, and simple to operate. Additionally, radius arms take up very little space under the rig. Because of this, they won’t run into binding issues with the exhaust or the oil pan—both of which are problems for vehicles that come stock with 4-links, such as the JK.
A 4-link setup on the other hand, attaches to an axle at two separate points and then to the chassis. The bottom two links locate the axle for back and forth movement, while the upper two links keep the axle from rotating freely. But there are two different styles of a 4-link setup: parallel and triangulated.
Let’s paint a picture with our words. On a parallel 4-link, you have the axle tubes attached by four forward links. On either side of the axle, the links run parallel to one another toward a mounting point on the chassis. A Panhard bar is mounted to the axle housing to help handle the axle’s lateral movement.
With a triangulated setup, only two of the links attach to the axle tubes, while the other two links run to the top center of the axle housing. The links on the tubes run directly forward to mount to the chassis, while the center links run out toward the mounting points of the outer links on the chassis which gives the system a triangular design. This design does not use a Panhard bar, as the triangulated design helps handle lateral movement of the axle.
“Basically, with a 4-link, 90% of the time all four links are adjustable, so you can do what you need to do: change your pinion angles, etc… There’s a LOT more adjustability with that,” says Naugle. This means better handling and articulation, both on and off-road. “Dual triangulated offers the best benefits, but it’s the most complex for install and packaging,” added Guyer.
It’ll Cost Ya
A big drawback, however, is price. On top of the cost of the 4-links kit, you’ll likely be laying out some big cash for installation, as this is not an easy job. In addition to needing some welding and fabrication skills, you really need to know what you’re doing. “Not many people can handle the geometry of the suspension,” Naugle says. “When you put in a 4-link kit, all your rod ends are adjustable, so you can screw up pinion angles very easily. You can give yourself death wobble with it. You can’t just bolt the kit on and drive away.”
A 4-link system can also experience some binding issues under extreme conditions. The links tend to run into the oil pan and the exhaust system—mostly the exhaust system. This issue can be managed, but it is definitely something you will need to be aware of to prevent damaging the vehicle.
So, Which Is It?
Despite how you may feel about that stock equipment, the facts are in: 4-links are superior for both on and off-road applications. But that doesn’t necessarily mean a 4-link setup is better for you. Depending on your needs, when should you invest in replacing those radius arms with a 4-link system, and when should you just consider upgrading what you’ve got?
Personally, I feel that the manufacturer sees fit to run particular components for a reason. If something didn’t work, OEMs wouldn’t use it. Radius arms have been known to perform well on off-road applications and manufacturers do offer aftermarket options. BDS, Rancho and Superlift are just a few off the aftermarket companies that answer to the demands of lifted radius arms suspension systems.
In my opinion, if you don’t plan on doing serious wheeling all of the time, you can stick to the radius arm setup. It will save you time and money and this is the sort of install you can likely tackle on your own.
Naugle disagrees. “In my personal opinion, you should upgrade. It gives you better handling characteristics just driving down the road.” Imagine how that could translate on the trail, he implies.
And, honestly, he has a point. In my experience with hot-rodding, moving to a 4-link system is the way to go when you want to improve handling and performance. Dragsters, road course, autocross, and even just standard street cars will benefit from upgrading from leaf springs to 4-links. “The same reasons you would have a 4-link rear suspension on a drag car translate into the off-road world. Same exact concept,” says Naugle.
Even though we are talking primarily about the front suspension, it is clear to me that the 4-link is regarded as the superior design by many. Especially when you take into consideration that the JK, an off-road titan by today’s standards, comes factory-equipped with 4-links.
A 4-link suspension system does perform better in just about every way. But the drawbacks are real. They are a lot of money and the install is highly complex. But hey, if you’ve got the capital and the itch to crawl rocks, it’s absolutely worth making this upgrade under any circumstances.