Shocks & Springs - Balancing Rebound
The first item people associate with suspension is springs and shocks. Older Wranglers (YJs) have leaf springs, while newer models have coil springs. Both are designed to absorb vertical impacts. When a vehicle goes over a bump or a hole, there is a vertical impact. The force of the impact is absorbed and distributed within the spring. The shock, or dampener, helps tame the energy absorption. If the vehicle were just on springs, it would continually bounce up and down when there was an impact. The up/down movement would continue until all of the energy absorbed by the spring is dispersed. A shock regulates and dampens that energy so the rebounding up/down movement is greatly reduced. This is why a stiffer shock results in a harsher ride as it quickly dampens the up/down movement. Also, some modern coil springs now come with different firmness rates, designed to react differently according to the pressure it’s absorbing.
VIDEO: How Jeep Suspension Works & Suspension Geometry
Improving Upon the Stock Wrangler Shocks
A gas filled Jeep shock tends to be stiffer than a hydraulic shock (the stock component). The stiffer compression allows for very little movement and rebound of the springs which translates to a quicker level of recovery if your Jeep goes over a bump in the road. A stiffer shock also contributes to a firmer stance and less body roll during tight turning. To ensure a good low center of gravity, it’s important to maintain the stock height level and use shocks designed for 0–2 inches of lift. These shocks can be direct replacements for the factory components and offer a significant improvement in handling over the stock shocks (assuming you’re not lifting your Wrangler).
Within this 0-2 inch range you can also find reservoir shocks. Although they are slightly more expensive, the additional reservoir body provides the main shock itself with a greater level of motion and fluid displacement. In addition, reservoir shocks do a better job of managing heat dissipation during excessive shock use on curvy paved roads or aggressive off-road conditions. This ensures a more consistent level of performance and prevents the shock from fading and underperforming.
JK Reservoir Shocks - 4-6 Inch Lifts
Marrying Stock Replacement Shocks with Appropriate Springs
Similar to stiffer shocks, a stiffer spring rate will also help with the overall handling of your Jeep. If you’re looking to improve your Jeep’s handling, it’s important to note a lower center of gravity is key to optimal handling. Lifting your Jeep’s height will counter this. The key is to find a set of springs with a stiffer compression rate than the factory springs, but without adding additional height. Within the spring family, there are three common types available for your Wrangler.
Linear springs: These are considered an entry level spring, commonly used in the stock Jeep suspension. They have a single spring rate. Although linear springs provide a consistent level of compression in average conditions, they are prone to fading and sagging over time and excessive use.
Progressively Wound Springs
Progressive springs: Progressive springs have a softer firm rate that gradually increases throughout the length of the spring. Progressive springs are designed to provide a softer ride during slower speeds and a firm ride during higher speeds or tighter cornering because the spring begins to compress further and engages the firmer spring rate. Due to the variance in spring rate, the coils tend to spread out more, resulting in a taller looking spring, which then compresses to the set height.
Dual rate springs: These are among the newest form of springs available, fusing two independent spring rates into a single coil. They are designed to act independently with the softer rate used at slower speeds and then form the base for the stiffer rate during higher speeds or tighter cornering. Dual rate springs tend to sit within the same height as linear springs and offer a greater center of gravity while still providing great travel during off-road use.
Do Bump Stops Help with Handling?
We understand during excessive handling conditions the springs are often fully compressed. Bump stops help ensure the springs aren’t compressed past their maximum point of compression. Wranglers come equipped with bump stops from the factory, but upgrading to a stiffer bump stop will ensure there is a less likelihood of over compressing the spring, which can also over compress and stress the shock as it tries to absorb the spring’s compression and rebound when unloaded.
3in Bump Stop Spacer Installed
Steering Stabilizers - Keeping a Straight Line
Similar to shocks, the steering stabilizer is designed to absorb impacts while driving and prevent any transfer of energy to the Jeep’s steering. Impacts at higher speeds can have an exponential reaction to the steering. Some argue the steering stabilizer isn’t a crucial component, and although it’s true a Jeep can function without one, the steering could be compromised if there is a strong enough impact.
Steering Stabilizer Installed and Put to Work
Control Arms - Angles are Everything
A major component often overlooked, especially with entry-level lifts, are control arms which serve two major functions. One is to correct the caster, and the other is to properly center (front-to-back) the axle/wheels within the wheel arches. Caster angle in particular is a difficult topic to explain. It’s basically the vertical axis of steering. Ideally, you want that angle to be in front of the tire's contact patch to the road, requiring a positive caster angle. Having that angle in front of the tire is what allows it to straighten out naturally when the steering is released. It also ensures a more accurate steering response.
Think of it as the wheels on a shopping cart. The attachment post of the wheels is in front of the swiveling wheel which allows you to steer the cart. If the angle is behind the contact point, a negative angle, then you will have unstable or “floaty” steering. This animated illustration demonstrates how the control arms are used to adjust the angle. You’ll notice when you are trying to achieve a positive angle, the upper control arms are pulled back while the lower control arms are extended.
The second problem control arms solve is the horizontal centering of the axles/wheels. As you lift a Jeep, the wheels are drawn in, seen in the animated illustrated below. The biggest problem faced when the wheels are drawn in is they could start to make contact with the frame of the Jeep, especially during extreme off-road articulation. Aftermarket control arms are extended to push out the axles so the wheels are properly centered again.
Finally, the reason control arms could be an issue with entry-level kits is because at the typical advertised lift estimate of 2.5 inches there isn’t enough of a change in suspension geometry to require these adjustments. However, the estimated lift height is always based on a fully loaded Jeep with heavy aftermarket bumpers. If you are running one of these entry-level kits on an otherwise stock Jeep, the real world lift is closer to 4 inches. At that range of lift, the caster angle and axle centering is greatly compromised, requiring at least front lower or upper control arms to help regain the correct positive angle and axle positioning.
Track Bars & "Death Wobble"
While control arms are used to center the axle front-to-back, the track bar centers the axle side-to-side. Similar to the front-to-back movement, when your Wrangler hits a bump in the road the axles also want to sway towards the driver’s side. The track bars are designed to keep the axles centered under the Jeep and prevent them from swaying towards the driver’s side.
The length of the track bar is important because it properly aligns the axles with the frame of the Jeep. If the Jeep is lifted, that adjustment is shifted towards the driver’s side. An adjustable track bar allows you to extend the length and push the axles back towards the passenger side and properly center it under the frame. There is a tremendous amount of pressure put on the front and rear track bars, making their two attachment points critical. A loose track bar is one the main culprits of “death wobble”, a violent shaking of the steering wheel when the Jeep hits a bump in the road. It is important to ensure these bolts are properly tightened and checked often.
Sway Bars - Wrestling Body Roll
A sway bar connects the left and right wheels to each other, both in the front and back, to reduce body roll when turning. As you go into a turn, to the right for example, the car will lean to the left, putting a great deal of weight on the left side and compressing the left suspension. As a result, the right side is lightened, and if the turn is aggressive, will actually lift the right wheel. The sway bar is designed to keep that right wheel down and minimize the shifting of the vehicle’s body weight. It distributes the energy of the pressure applied to the left over to the right in order to keep both tires in contact with the road and reduce weight shifting or what is called “body roll”.
Replacing your factory sway bar with thicker aftermarket alternatives will have a big impact in overall handling. The thicker sway bar will prevent unnecessary flexing during cornering and will ensure a flat stance overall, which helps keep the tires in full contact with the road. Aftermarket sway bars have no influence during off-road conditions since the sway bar links are often disconnected while on the trail. This upgrade solely has an impact on paved roads when the links are engaged.
Front Sway Bar for 4-6in Lifted Wranglers
Sway Bar Links - Stiff On-Road, Loose Off-Road
These links attach the sway bar to the wheels. They have a specific length to ensure the sway bar is close to flat, or very slightly raised. When lifting a Jeep, the space between the sway bar and wheels is increased. If you use the same factory links, this will create a downward angle that could be dangerous and actually reduce the performance of the sway bar. Adjustable aftermarket links extend and allow you to regain the correct angle.
Sway bar links are also commonly removed when off-roading, allowing the wheels to alternate articulation and maintain contact with uneven terrain. Rubicon models have a sway bar that is basically split in the middle. The points are mated to a gearbox that keeps both ends engaged and mimic a solid piece when the Jeep is on the road. When the button is pushed to disconnect the sway bar, the gearbox allows both ends to rotate independently, acting as if the sway bar links were removed.
Front Sway Bar Quick Disconnects Installed
Bushings - Making Your Suspension Accurate
Although it may sound silly, the bushings on your steering components can affect how your Jeep handles. Wranglers typically come with rubber bushings which are cheap, insulate from road vibration, and are maintenance free.
However, the problem with these rubber bushings is they flex, stretch, and compress. This allows your alignment to become off when cornering, possibly hindering your handling. An inexpensive way to improve your handling is to replace these bushings with polyurethane bushings which are more durable, stiffer, and inexpensive. The benefits to polyurethane not only include a longer lifespan, but also they will not flex, stretch, and compress which will help prevent the slight changes in your alignment.
YJ Master Bushing Kit
The Importance of Center of Gravity
Unfortunately, a Wrangler with a 6 inch lift kit is going to have much worse handling than stock. This is due to the center of gravity shifting upwards. As everyone knows, Jeep Wranglers are considered “rollover vehicles” meaning they are a bit more likely to roll than other vehicles. This is due to the weight of the Jeep being higher up. An easy way to look at this is to compare it to carrying a heavy box. If you hold the box above your head and try to run around in circles you will probably fall over. However, if the box is held at your waist you can avoid falling over. So as you lift your Wrangler you are holding the box higher. Not only does a high center of gravity make it easy to roll over, it also reduces handling due to the vehicle leaning causing the weight to shift away from the inside tires. Obviously, there are very few people who would want to lower their Wrangler. Instead, the best approach is to simply avoid lifting your Jeep excessively high. If a tall lift kit has already been installed, you could remove it and install one a size or two smaller.
JK with a 6in Lift Kit
Fitment includes: JL, JK, TJ, YJ, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, Laredo, Sport, Islander, S, Sahara, Renegade, SE, X, Rubicon, Unlimited, Sport-S