Control Arm Tech 101Posted in How To: Suspension Brakes on September 1, 2010 Comment (0)
Over the past few years suspension technology has evolved substantially. With desert-ready race truck platforms rolling off the factory showroom floors and purpose-built buggies regaining momentum, fresh ideas and designs are flooding the 4x4 industry. While the rock star of the suspension world is undoubtedly the shock absorber, the overworked roadies who pull the show together are the control arms.
Since the control arms are what link the axle to the vehicle, they need to be incredibly durable. Although factory suspension links are tougher than ever before, the aftermarket is rich with control arm upgrades, from high-clearance arms to featherweight aluminum links. With so many control arm options, it can be difficult to determine what's right for your rig. So to help you weed through it all in your quest for better suspension links, we've put together a little basic control arm info.
The most widely supported multilink suspension platform is the '97- '06 Jeep Wrangler TJ & '07- present Wrangler JK. Both the factory TJ and JK arms are nonadjustable and fitted with rubber bushings at both ends. Though the factory Wrangler arms might not be as trick as some of the aftermarket links, the stock arms and bushings are pretty durable and work well inside the factory travel parameters. While new JK arms are great improvement over the older TJ arms, their lack of adjustment can lead to caster and driveline issues after you raise the Jeep more than a few inches.
Thick Of It
Link material thickness and tubing diameter often reflect the vehicle's intended use and overall weight. For many light-duty platforms 0.250-wall DOM tubing is commonly used and plenty strong. On heavier and more extreme applications a thicker tubing wall is often used as the increased density and diameter can accommodate more weight and abuse.
As more 4x4 builders are becoming weight conscious, we are seeing a rise in aluminum links. Aluminum is an incredibly strong and lightweight metal, but it isn't without drawbacks. The surface of aluminum links can be more easily damaged. To compensate for this, some of aftermarket link manufactures will equip the bottom of the aluminum control arm with a removable steel skid to protect the link from rock rash and damage.
High-clearance arms are a great way to extend the length of your control arms and improve your suspension without losing ground clearance. A single link bend is fine; too many complex bends in a control arm can weaken the link. If arched links are not an option for your rig, look for ways to mount the links alongside or within the vehicle's framerails. The goal is to have a functional suspension setup with limited ground clearance loss.
Adjustable control arms allow you to fine-tune your axle's position, caster, and wheelbase. We suggest looking for arms that have adjustment collars built into the link or are built with left- and right-hand threads so removal of the arm will not be necessary when adjusting the link.
Control arm joints and endlinks are what help the suspension to articulate freely and absorb much of the road vibration. While each joint style has its own pros and cons, we prefer greaseable units like the Currie Johnny Joint for rigs that see a mix of highway and off-road use. Before purchasing joints for your rig, investigate their serviceability, range of motion, strength, and versatility for your environment.
For years desert racers and prerunners alike have used lower plated trailing arms to mount their shocks and coilovers. Unlike conventional links comprised of tubing, these arms use laser-cut, reinforced pieces of plate welded together. Factoring in mechanical advantage and custom shock valving is all part of this suspension equation, but given the space and time, the strength and travel benefits of a trailing arm setup are well worth it.