Suspension Bushings Tips, Diagnosis and Repair
Bushings provide a cushion between suspension parts to minimize and dampen vibration by reducing the energy transmitted between components. You can compare bushings to cartilage between joints in our body. Although extremely durable, over time these suspension bushings can wear out and cause a number of suspension problems. Automotive suspension systems are very complex and should be inspected or maintained by a professional. Listed below are some of the common signs of bad bushings:
Squeaking, creaking, and clunking coming from your suspension is a big indicator of failing bushings. These sounds may be more noticeable during turns or on bumpy roads as the suspension parts shift abnormally. Defective bushings can also cause alignment problems, as the components move back to their natural position.
Soft suspension bushings are sometimes desired over firmer ones because they are better at absorbing noise and reducing vibration. Soft bushings typically don't last as long as firmer ones and can lead to premature excessive flexing and sloppy steering. Whether firm or hard, if these bushings fail they can cause dangerous steering problems such as delayed response or improper travel.
Poor Ride Quality
A change in ride comfort could also be a sign of suspension bushing problems. Control arm bushings are more susceptible to failure and are a common cause of these problems. And bushings connected to major systems are more likely to cause bigger problems.
Bushings are typically used on the following automotive suspension parts: control arms, sway/stabilizer bars, shocks, struts, ball joints, steering racks, tie rods and a variety of mounts. Bushings typically crack and wear from friction, lubricants, water, heat, road salts, and the stress from increased weight loads. Sporty, low-profile tires also transfer more stress to bushings. Typically, the bushings themselves don't cost a lot, but the labor to mount them can be expensive.
Tips for Diagnosis and Repair
It is important to refer to your vehicle's maintenance manual for specific bushing inspection and replacement information. Some manufacturers recommend replacing a bushing if it fails a deflection check, while others recommend replacement based on the length or depth of tears or cracks. If you follow these procedures, you can save time and money by not wasting your efforts on bushings in good condition.
Some modern bushings contain hydraulic fluid, which is prone to leaking when damaged. Hydraulic bushings are tuned to the suspension and the tire package. If leaks are detected, the bushing should be replaced immediately, as leaks aren’t likely to be repaired.
It is critical to properly torque all suspension parts and bushings with a torque wrench. Over-torquing can damage certain suspension parts, while under-torquing can cause premature failure. Also, keep in mind that many fasteners are torque-to-yield, which means the fasteners are designed to expand when torqued to ensure they stay tight over time. Never use an impact wrench to install suspension parts – they prevent precise torquing and can damage sensitive suspension parts.
Despite some aftermarket manufacturer claims, do not replace hydraulic bushings with solid bushings. This can compromise ride quality and performance. If bushings are defective on control arms, sway bars or other suspension parts, it may be more cost effective to replace the entire assembly because certain bushings can be labor-intensive.
You’ll want to thoroughly investigate why a bushing or other suspension part failed. If not, you can replace the part, and it can fail again prematurely. For example, fluid leaks in the area need to be corrected before replacing the failed part. Factors such as fluid and extreme heat can quickly ruin some bushings.
Many suspension systems will require special tools and thread lockers. Also, it's not uncommon for suspension systems to be designed using cast and forged aluminum. Fastening aluminum to other dissimilar metals can create corrosion. Some manufacturers used coated hardware to help minimize corrosion. The coated hardware can usually be identified by a chalky black or green coating. Some of the hardware is designed to be only used once. On some vehicles, thread lock compound is used to secure bolts and other hardware.