Avoiding Suspension Problems in the Kenworth T800: Diagnosis and Solutions

Learn how to diagnose and solve common suspension problems in your Kenworth T800 heavy-duty truck. Ensure safety, comfort, and top performance during long hauls.
Suspension repair in repair shop

The Kenworth T800 is designed for the most challenging jobs, and its suspension system is no exception. Built to withstand heavy loads and challenging road conditions, it's an integral part of your heavy-duty truck that ensures safety, comfort, and optimal performance during long hauls. 

Here, we will delve into the common suspension problems that your Kenworth T800 may experience, their accurate diagnosis, and how to resolve them. 

Common Suspension Problems in the Kenworth T800

Suspension issues can disrupt your truck's performance and, more importantly, compromise safety. Understanding how to recognize suspension issues is critical for any driver or fleet manager.

Sagging Suspension: Worn-out leaf springs or airbags can cause your suspension to sag. For leaf springs, look for cracks or flattened leaves. For airbags, check for air leaks or damaged bags.

Uneven Tire Wear: Misaligned or damaged suspension components cause uneven tire wear, such as cupping or feathering. This can impact tire lifespan, handling, and fuel efficiency.

Excessive Bouncing: Worn-out shocks can cause your truck to bounce excessively over bumps, affecting handling and driver comfort.

Steering and Handling Problems: Worn-out components like control arm bushings can make steering unstable during turns or rough road conditions.

Noisy Suspension: Knocking, squeaking, or rattling sounds often point to loose or damaged suspension components. Common culprits include worn bushings, shock mounts, or loose bolts.

Bottoming Out: When the suspension fully compresses, bottoming outs happen and cause the chassis to hit the road or frame components. It's often due to worn springs, low air pressure, or overloading.

Excessive Roll and Sway: Problems with sway bars or anti-roll bars cause excessive body roll or sway during cornering. These components need close inspection for wear or damage.

Diagnosing Suspension Problems

Accurate diagnosis is the key to efficient and effective repairs. With these steps, you can pinpoint suspension issues with precision.

Visual Inspection

Start with a thorough visual inspection. Look for cracks, wear, or misalignment in suspension components such as springs, shocks, control arms, and bushings.

Listening for Clues

Pay attention to your truck's sounds while driving. Worn bushings, shock mounts, or loose bolts can cause knocking, squeaking, or rattling noises.

Professional Diagnosis

While DIY inspection is valuable, some issues require advanced tools. Professional suspension mechanics can use suspension analyzers to measure and diagnose problems with precision, especially those related to shock absorber effectiveness, alignment, and geometry.

Wheel Alignment Check

Proper wheel alignment is critical. Precision tools are used to measure and adjust wheel angles, ensuring even tire wear, better handling, and improved fuel efficiency.

Load Testing

Load testing simulates the weight your truck carries during regular operations. It reveals issues like sagging or excessive bounce when the vehicle is under load, which may not be apparent during a stationary inspection.

Diagnostic Trouble Codes (DTCs)

Modern Kenworth T800s may store diagnostic trouble codes related to suspension issues. Scan tools can retrieve these codes, offering insights into specific problems requiring attention. However, this will most likely require professional diagnostics and electrical assistance.

Suspension Repairs

Adjusting Air Suspension Pressure

For Kenworth T800s equipped with air suspension systems, adjusting air pressure is a crucial maintenance task that requires a reliable air pressure gauge. Use your truck's manual for recommended air pressure levels based on load capacity. Using the gauge, measure the current pressure in the airbags. 

To increase pressure, add air through the inflation valve; to decrease it, release air. Properly adjusting air pressure can correct issues like sagging and improve ride quality.

Replacing Shock Absorbers

Shock absorbers play a crucial role in controlling the movement of your suspension. Worn-out shocks can result in excessive bouncing and compromised handling. 

To replace them, locate the shock absorbers near the wheels. Lift the truck to access them safely. Using appropriate tools, replace the old shocks with new, manufacturer-recommended ones. Ensure you follow the torque specifications provided by the manufacturer during installation to guarantee optimal performance.

Replacing Leaf Springs

If you've identified worn or damaged leaf springs as an issue, replacing them is essential for maintaining load-bearing capacity and overall suspension integrity. Start by safely lifting the truck and securing it. 

Locate the leaf springs, which are situated parallel to the chassis. Carefully detach them from their mounts and remove the old springs. Install new leaf springs following the manufacturer's instructions. Pay close attention to the proper torque settings for bolts and fasteners. This ensures that the new springs provide the necessary support and alignment for your Kenworth T800.

Airbag Replacement

In air suspension systems, airbags can develop leaks or suffer damage over time. To replace them, deflate and depressurize the air suspension system per the manufacturer's guidelines. Remove the damaged airbag and install the new one, ensuring a secure connection to the suspension components and air supply. Properly inflate the airbag to the recommended pressure levels to maintain the truck's ride height and load-carrying capacity.

Wheel Alignment

Precision wheel alignment involves measuring and adjusting three key angles: camber, caster, and toe. These angles dictate how the tires make contact with the road surface and influence tire wear and handling stability. 

Mechanics use specialized alignment equipment to measure these angles and adjust them to meet manufacturer specifications. For instance, the camber is the vertical angle of the wheels. Positive or negative camber can lead to uneven tire wear if not corrected. Camber influences steering stability. Toe alignment controls whether the front tires point inward or outward. Proper alignment ensures even tire wear and stable handling.

Advanced Suspension Diagnostics

Suspension Analyzer

Suspension analyzers are sophisticated diagnostic tools that assess the performance of various suspension components. They measure factors such as suspension geometry, damping characteristics, and load distribution. 

By connecting these analyzers to your Kenworth T800's suspension system, mechanics can identify any discrepancies or irregularities in the suspension's behavior post-repair. This step is critical to ensuring that the repairs have restored alignment, geometry, and load-bearing capabilities to factory specifications.

Computerized Suspension Analysis

Computerized suspension analysis systems offer in-depth data on the suspension's performance. They provide precise information about shock absorber behavior, alignment angles, and load distribution. 

Mechanics use this data to fine-tune the suspension further and verify that it operates optimally. Computerized analysis ensures that the suspension system is not only repaired but also optimized for the specific requirements of your Kenworth T800.


Maintaining the suspension system of your Kenworth T800 is vital for both safety and performance. Recognizing common suspension problems, from sagging suspension to excessive bouncing, is the first step toward efficient diagnosis and resolution. Proper maintenance tasks, including adjusting air suspension pressure, replacing worn components, and ensuring precision wheel alignment, are essential for keeping your truck in top condition. 

By following these guidelines and investing in regular suspension maintenance, you can ensure that your Kenworth T800 continues to excel in the most demanding of tasks, delivering safety, comfort, and top-tier performance during every long haul.

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