Sean P. Holman
Contributor
A case could easily be made that suspension is the most important system on your 4x4. It is suspension that gives your rig the ability to drive over any road in comfort. It is suspension that allows you to traverse extreme terrain while keeping your tires on the ground. It is suspension that allows you to safely carry a load and still navigate a twisty road. Quality suspension also protects other systems on the vehicle from excessive shock and vibrations. So what do you do when your suspension develops a problem? How do you know when is a squeak just a squeak, and when does it become a life-threatening problem?
Diagnosing suspension problems can be frustrating, expensive, and time-consuming. It doesn’t matter if you have some clapped-out old ride or a high-dollar trail rig, no vehicle is immune from the problems associated with suspension. To help you understand the issues your rig faces, we compiled this general list of common suspension-related problems you may find on your 4x4.
Whether you are currently narrowing down suspension issues on your rig or not, it is important to remember to always inspect, re-torque, and grease your suspension components after every outing. This proper maintenance is the key to prolonging the life and durability of any suspension.
Bent Shock Shaft
What They Do: Shock shafts are part of the suspension system that damps wheel movement before it reaches the vehicle. The shock shaft, or piston rod, carries the shock piston on one end and provisions for mounting it on the other.
Bent shock shafts aren’t uncommon, but it takes a serious load to bend one like this.
Symptoms: A bent shock shaft can cause a loss of shock travel, leaking seal (but not always), and a stiff ride depending on how severe the bend is.
Why They Go Bad: Common reasons for a bent shaft include hitting it against an object, improper suspension geometry, improper mounting or excessive misalignment, or over-articulation.
How To Fix: Usually this will require replacement of the shock, although most types of racing-style shocks can be rebuilt. The repair should always come with proper understanding of why the failure occurred in the first place.
Bad Ball Joints
What They Do: A ball joint is a spherical bearing that connects the steering knuckle to the control arm or axle. Ball joints allow the steering knuckle to be turned by the tie rod smoothly and without binding and are the pivot point between the wheels and suspension. On IFS-equipped vehicles, a ball joint has the additional duty of moving in a vertical plane with the control arms.
When modifying your rig to use larger wheels and tires, stock ball joints become a weak link in your suspension. Heavy-duty rebuildable and serviceable ball joints are an important upgrade to any 4x4 that is modified or sees heavy trail usage.
Symptoms: Early symptoms of a ball joint going bad could be wandering and/or clunking. In severe cases, the ball joint can completely fail causing the separation of the steering knuckle from a control arm. This would result in the driver losing control and crashing.
Why They Go Bad: Ball joints are made in both serviceable and non-serviceable variations. Serviceable ball joints need to be lubricated on a regular basis and non-serviceable ball joints become an issue once the seal breaks, as the joint will dry out and begin to rust. From there it is only a matter of time until failure. Other issues that can cause ball joint failure are larger and heavier wheels and tires, increased wheel backspacing, and on IFS rigs, overextension of the suspension.
How To Fix: Heavier-duty replacement ball joints are available in the aftermarket. This Dodge Ram suffered from severe frontend oscillations that were tracked down to a loose aftermarket track bar bracket.
Symptoms: Track bars take a lot of load and an improperly adjusted, damaged, or loose track bar can cause the axle to sit off-center, cause clunking or popping when steering or going over bumps, and can cause the steering wheel to be off-center. A telling sign that there is a problem with a front track bar is a front axle that moves laterally with the steering wheel.
Why They Go Bad: Track bars can bend or break after suspension modifications or improper installation techniques. Improper grade bolts can break, while the wrong-sized bolt can oval-out or otherwise damage a bushing. Common hardware failures result from failure to re-torque after install. Normal wear and tear can also take their toll on track bars.
How To Fix: Track bars that suffered from a hardware failure should be properly reinstalled and torqued to spec. Failed track bars should be rebuilt or replaced, depending on the type of damage to the bar.
Sheared Shock Mounts
What They Do: Shock mounts support shocks and coilovers, providing a solid foundation for the suspension.
Here is a great example of a sheared shock mount. This aftermarket hoop was welded to the frame, but over time the sub-standard welds failed. The only things holding this hoop to the truck are the shocks.
Symptoms: Depending on the type of suspension setup, a broken shock mount can be a serious problem or just a headache. Broken shock mounts can cause noises over bumps, handling problems, and affect ride quality.
Why They Go Bad: The most common reason we see shock mount failure is because of poorly welded mounts that cannot support the loads generated by the shock. Other common reasons for shock mount failure are the use of improper length shocks, improper hardware, lack of limit straps, or missing bumpstops.
How To Fix: A qualified welder should re-weld any broken shock mounts, and any secondary problem should be addressed.
Leaking Shock Seals
What They Do: Seals separate the nasty outside world from the clean inside of your shocks.
Symptoms: Oil on the shock body is the easiest way to discover a leaky shock seal, although shocks with leaky seals can also cause vehicle lean and a floaty ride.
Why They Go Bad: Seals can go bad for a number of reasons, such as a shaft that is pitted from exposure to rocks and gravel. Once a shaft is pitted, rust can take hold and then it severely shortens the life of the shock. Wheeling in muddy or salty terrain can also compromise the integrity of the seal, as can overheating the shock, which can melt the seal completely or alter its shape.
How To Fix: Just as with a bent shock shaft, some shocks can be rebuilt, and others just need to be replaced.
Broken Leaf Spring
What They Do: Leaf springs are a design of spring that both carries weight and sets ride height of a vehicle. They also locate the axle without the need for additional control arms.
This leaf spring was damaged when the owner removed too many of the support leaves in search of a better ride. As simple as they appear, leaf springs are highly engineered assemblies that should only be modified by a qualified shop.
Symptoms: You know you have an issue when you see an individual leaf sticking out of the pack. Other symptoms can be noise, lean, or an axle that is not centered.
Why They Go Bad: Leaves may be one of the most durable components on any 4x4, but metal fatigue, overloading, and overextension or compression of the suspension can all contribute to broken leaf packs. Other things to consider are a lack of maintenance or substandard spring material.
How To Fix: As a general rule, leaf springs can be rebuilt, but sometimes a new spring pack is the answer. Whether your pack is new or rebuilt, it should be manufactured with quality materials and parts and should be pulled apart from time to time and inspected. This ensures small problems are caught before they turn in to big problems.
Problematic U-bolts
What They Do: U-bolts secure the leaf spring pack to the axle.
U-bolts are an often forgotten, but play a critical role in any leaf-sprung suspension.
Symptoms: If your U-bolts are going bad, you may notice that your spring pack is “walking” or that the axle has shifted. Bad U-bolts can also cause your pinion angle to change, resulting in driveshaft vibrations. Other areas of concern are clunks and noises as well as a loss of ride height.
Why They Go Bad: U-bolts, like any other suspension-related component, need to be maintained. Regular inspection of the often-forgotten U-bolt can catch stretching or corrosion issues. Adding significantly more power or weight to your rig without upsizing the U-bolts can also cause breakage, as U-bolts are not a one-size-fits-all component.
How To Fix: The easy answer is new U-bolt hardware. If you live in an area where corrosion is an issue, coated U-bolts are available for increased durability. Regular inspection and re-torquing can also catch problems early. U-bolts should never be reused and should always be replaced whenever the spring is removed.
Center Pin Failure
What They Do: Leaf spring center pins align the axle with the spring.
From L to R: A damaged center pin, a replacement center pin, and a Grade 8 hex head upgrade. Factory center pins are typically only Grade 2 hardware. Upgrading to Grade 8 can make your leaf pack more durable.
Symptoms: Broken center pins can cause problems, such as shifted axles and noise, but the really nasty failures could rip out a driveshaft, brake lines, and even cause body damage.
Why They Go Bad: OE-style center pins are Grade 2 hardware, designed to shear in the event of an accident to save the axle. While this is great for street use, 4x4s require heavier-duty hardware, such as the Grade 8 center pins available in the aftermarket. Other causes of center pin failures can include loose or stretched U-bolts as well as excessive torque going to the axle.
How To Fix: A quality spring shop can rebuild your pack with new center pins. If you are experiencing center pin failures, an upgrade in hardware grade may be the solution.
Saggy Springs
What They Do: Springs keep the tires in contact with the road, carry load, and set ride height.
Symptoms: All springs, whether it is a coil, a torsion bar, or a leaf, will someday begin to lose rate and sag. Saggy springs are the cause of a loss of ride height and poor handling, as well as degradation in ride. Worn springs can also cause tires and other components to wear prematurely.
Why They Go Bad: Natural wear and tear and metal fatigue will cause a spring to lose its elasticity.
How To Fix: Sagging springs require replacement.
Losing Weight
What They Do: Wheel weights are used to balance the rotating mass of a wheel and tire package.
Problems from tire balance can occur when weights fall off the wheel. Adhesive-style weights are less likely to get knocked off by rocks, but can still fall off on their own.
Symptoms: Tires that are out of balance can cause vibration and degrade ride and handling. Tire balance issues can be detected in the ride, through the steering wheel, or as a wheel rhythmically hopping at speed.
Why They Go Bad: With today’s adhesive weights, it isn’t uncommon for weights to fall off a wheel while on the trail, leading to balance issues on the ride home. The vibrations caused by an out-of-balance wheel and tire can cause premature wear of the tires, bushings, bearings, and other suspension components.
How To Fix: Inspect wheel weights after each outing and have wheels and tires re-balanced if necessary, replacing any missing weights.
Blown Bushings
What They Do: Bushings are used throughout a vehicle’s suspension system to isolate vibrations and control movement.
This picture illustrates the difference between a rotted-out vs. new rubber bushing (top), a worn out vs. new rubber bushing (middle), and a failed vs. new polyurethane bushing (bottom).
Symptoms: Bushings are the primary cause of suspension noise. They can also contribute to rattles, wandering, handling issues, and unwanted axle movement.
Why They Go Bad: Bushings suffer from normal wear and tear, but can have life shortened even further from heat, oil, or other contaminates. On bushings that require lubrication, lack of maintenance can also cause premature failure.
How To Fix: Blown bushings should be replaced. Heavier-duty alternatives should be explored when available.
Bumpstop Bummer
What They Do: Bumpstops limit suspension travel on compression, preventing interference between the suspension and frame or body and acting as a final suspension cushion.
Symptoms: If you are hearing metal on metal contact as your suspension compresses, then you should immediately inspect your bumpstops.
Why They Go Bad: Bumpstops can be made out of all types of material, from rubber to polyurethane. Bumpstops can crack, break, or in the case of OE-style push-fit, they can just fall out.
How To Fix: Damaged or missing bumpstops should be replaced immediately.
Under Pressure
What They Do: Tire pressure is used to set tire load and prevent heat buildup at highway speeds.
Symptoms: Over or underinflated tires will have premature wear. Overinflated tires will exhibit a rough ride, while underinflated tires will cause sloppy handling.
Why They Go Bad: We see it all the time and our common response to this is user error. Just because a tire says its max load is at 65 psi, doesn’t mean that tire should be inflated to 65 psi. This is for maximum load only and typically the proper inflation will be substantially less. For example, a set of 37-inch tires on one of our project vehicles has a max-load inflation of 3,500 pounds at 50 psi. That means at max inflation the tires could carry 14,000 pounds. Since our rig only weighs 6,000 pounds, we determined through the chalk test that it requires only 28 psi.
How To Fix: Use the chalk method to determine proper air pressure of tires on your rig.
A Note on Death Wobble
Death wobble is a huge topic amongst those lifting coil-link-style solid axle vehicles and is a blanket term that is often used to describe a series of sudden and violent frontend vibrations that can range from severe bumpsteer (although bumpsteer is a completely different issue) to very serious and dangerous frontend oscillations. If you have it, there is no mistaking what it is. Death wobble, if ignored, can lead to serious damage to other components and even loss of vehicle control. There is no one cure to death wobble, but the shops we spoke with agreed that they would start diagnosis by replacing any known worn parts and inspecting the tire pressure, tire balance, track bar, and caster settings. From there the entire frontend needs to be gone through, one component at a time. Solving death wobble can be a slow and expensive process of elimination. In reality, no one problem causes death wobble, but rather any combination of the things mentioned in this story can contribute to it. If you experience death wobble, let off the gas and let the vehicle slow on its own until the vibration is gone, then proceed carefully to a qualified 4x4 shop immediately.
