From L to R: A damaged center pin, a replacement center pin, and a Grade 8 hex head upgrad
Center Pin Failure
What They Do: Leaf spring center pins align the axle with the spring.
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.
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.
Problems from tire balance can occur when weights fall off the wheel. Adhesive-style weigh
What They Do: Wheel weights are used to balance the rotating mass of a wheel and tire package.
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.
This picture illustrates the difference between a rotted-out vs. new rubber bushing (top),
What They Do: Bushings are used throughout a vehicle’s suspension system to isolate vibrations and control movement.
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.
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.
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.
14102 Stowe Drive
902 E. 2nd Street
Off Road Evolution
1829 W Commonwealth Avenue