Aligning tandem trailer axles isn’t a task to be taken lightly; proper alignment is paramount to safe towing, extended tire life, and reduced wear and tear on your trailer’s suspension. Misaligned axles lead to uneven tire wear, increased fuel consumption, and potentially dangerous instability.
Why Tandem Axle Alignment Matters
Tandem axles, commonly found on larger trailers used for hauling everything from boats and construction equipment to livestock, distribute the trailer’s weight more evenly than a single axle. This improves stability and allows for heavier loads. However, the interconnected nature of a tandem axle system means that misalignment in one axle significantly impacts the others. When axles are misaligned, tires are forced to scrub against the road surface, generating excessive heat and rapidly wearing down the tread. This scrubbing also puts undue stress on suspension components like leaf springs, equalizers, and bushings, leading to premature failure. Furthermore, a misaligned trailer will not track properly behind the tow vehicle, resulting in increased fuel consumption and a potentially dangerous handling experience, especially at highway speeds.
Understanding the Alignment Process
The process of aligning tandem trailer axles involves several key steps, primarily focused on ensuring that the axles are parallel to each other and perpendicular to the trailer frame. This often involves measuring distances, adjusting suspension components, and verifying the alignment using specialized tools.
Types of Tandem Axle Misalignment
Before diving into the alignment process, it’s crucial to understand the common types of misalignment:
- Toe: This refers to the inward or outward angle of the tires when viewed from above. Incorrect toe causes tires to scrub diagonally across the road surface.
- Camber: Camber describes the inward or outward tilt of the tire when viewed from the front or rear of the trailer. Excessive camber leads to uneven wear on the inside or outside edge of the tire.
- Axle Squaring: This relates to the axles not being perfectly perpendicular to the trailer frame. An un-square axle forces the trailer to “dog track,” where the trailer follows a slightly different path than the tow vehicle.
- Axle Parallelism: This refers to the axles not being perfectly parallel to each other. Non-parallel axles put stress on the suspension and cause irregular tire wear.
Tools and Equipment Needed
While a professional alignment shop has specialized equipment, you can perform basic tandem axle alignment checks and adjustments with a few essential tools:
- Measuring Tape (Long, Accurate): Crucial for measuring distances between reference points on the trailer frame and axles.
- Level: Used to check the levelness of the trailer frame.
- String Line or Laser Level: Helps to create a straight reference line for comparing axle positions.
- Wrenches and Sockets: Necessary for adjusting suspension components and U-bolts.
- Torque Wrench: Ensures that fasteners are tightened to the correct specifications.
- Jack and Jack Stands: For safely lifting and supporting the trailer.
- Wheel Chocks: To prevent the trailer from rolling.
- Optional: Angle Finder or Digital Level: Provides more precise angle measurements for camber adjustments.
The Step-by-Step Alignment Procedure
Safety is paramount! Ensure the trailer is parked on a level surface, wheels are chocked, and the trailer is properly supported on jack stands before beginning any work.
- Initial Inspection: Begin by visually inspecting the tires for uneven wear patterns. Also, check the suspension components for damage or wear, such as cracked leaf springs or worn bushings.
- Frame Leveling: Ensure the trailer frame is level from side to side and front to back. Adjust the jack stands as needed. An unlevel frame will skew alignment measurements.
- Axle Squaring Measurement: Measure the distance from a consistent point on the front of the trailer frame to the center of each axle’s spring perch. Repeat the measurement on the rear of the trailer frame to the same spring perch locations. The measurements on each side should be as close to identical as possible. Significant differences indicate that one or both axles are not square with the frame.
- Axle Parallelism Measurement: Using a long measuring tape, measure the distance between the front axles at a specific point (e.g., the center of the tire). Repeat this measurement at the rear axles at the same point. The difference between the front and rear measurements should be minimal (ideally within 1/8 inch). A larger difference indicates that the axles are not parallel.
- Toe Measurement: Use a string line or laser level positioned parallel to the side of the trailer. Measure the distance from the string line to the front and rear of each tire. Subtract the front measurement from the rear measurement. A positive value indicates toe-in, and a negative value indicates toe-out.
- Camber Measurement: Using a level and angle finder (or digital level), measure the angle of each tire relative to vertical. Ideally, camber should be close to zero degrees, but a slight positive camber (tire leaning slightly outward at the top) is often acceptable.
- Adjustment: Adjustments will depend on the type of suspension and the nature of the misalignment.
- Leaf Spring Suspension: Axle squaring and parallelism can sometimes be adjusted by loosening the U-bolts that secure the axles to the leaf springs and slightly shifting the axle position. This requires careful measurement and iterative adjustments. Toe and camber adjustments are typically not possible without specialized equipment.
- Torsion Axle Suspension: Adjustments are generally not possible with torsion axles. Misalignment typically indicates a bent axle or damaged torsion arm, requiring replacement.
- Re-Measurement and Verification: After making adjustments, re-measure all parameters to ensure that the alignment is within acceptable tolerances.
- Torque and Secure: Once the alignment is satisfactory, torque all U-bolts and fasteners to the manufacturer’s specifications.
Important Note: For more complex alignment issues, especially those involving bent axles or damaged suspension components, it is highly recommended to consult with a qualified trailer mechanic. They possess the specialized equipment and expertise to diagnose and repair these problems correctly.
Frequently Asked Questions (FAQs)
FAQ 1: How often should I get my tandem trailer axles aligned?
Axle alignment should be checked at least annually, or more frequently if you notice signs of misalignment such as uneven tire wear, poor handling, or excessive vibration. New trailers should also be checked shortly after purchase, as settling can occur during initial use.
FAQ 2: What are the signs of misaligned trailer axles?
Common signs include:
- Uneven or rapid tire wear.
- Poor trailer handling and instability.
- Increased fuel consumption.
- Excessive vibration.
- Squealing tires during turns.
- Visual misalignment (axles not appearing parallel or perpendicular).
FAQ 3: Can I align my tandem trailer axles myself, or do I need a professional?
Basic checks and minor adjustments (e.g., axle squaring) can be performed by experienced DIYers with the right tools. However, complex issues like bent axles, damaged suspension, or precise toe/camber adjustments require professional equipment and expertise. Incorrect adjustments can worsen the problem and create safety hazards.
FAQ 4: What is the cost of a professional tandem axle alignment?
The cost varies depending on the shop, the type of trailer, and the extent of the work required. Expect to pay anywhere from $200 to $600 or more for a professional alignment, including any necessary parts replacement.
FAQ 5: How do I know if my trailer axles are bent?
Visual inspection can sometimes reveal a bent axle. Look for signs of bending, kinking, or unusual wear patterns. However, subtle bends can be difficult to detect without specialized measuring tools. A professional alignment shop can use precision instruments to determine if your axles are straight.
FAQ 6: What are the acceptable tolerances for tandem axle alignment?
Acceptable tolerances vary depending on the trailer type and manufacturer’s specifications. However, a general guideline is to aim for axle squaring and parallelism within 1/8 inch, and toe and camber as close to zero degrees as possible. Consult your trailer’s owner’s manual or a qualified mechanic for specific recommendations.
FAQ 7: Can overloading my trailer cause axle misalignment?
Yes, consistently overloading your trailer can stress the axles and suspension components, leading to premature wear and misalignment. Always adhere to the trailer’s weight capacity and distribute the load evenly.
FAQ 8: How does terrain affect tandem axle alignment?
Regularly towing on rough or uneven terrain can accelerate wear and tear on the suspension, increasing the likelihood of misalignment. Consider using heavy-duty suspension components if you frequently tow in challenging conditions.
FAQ 9: What role do trailer tires play in axle alignment?
While tires don’t directly cause misalignment, improperly inflated tires or using mismatched tire sizes can exacerbate existing alignment issues and accelerate tire wear. Always maintain proper tire pressure and use tires of the same size and type on each axle.
FAQ 10: Can I use shims to adjust trailer axle alignment?
Shims can sometimes be used to make minor camber adjustments on certain types of suspension. However, they should only be installed by experienced professionals who understand the correct application and potential consequences. Improper shim installation can create further problems.
FAQ 11: What type of maintenance should I perform to help maintain tandem axle alignment?
Regular maintenance includes:
- Checking tire pressure.
- Lubricating suspension components.
- Inspecting for worn or damaged parts.
- Ensuring U-bolts and fasteners are properly torqued.
FAQ 12: Where can I find a reputable tandem axle alignment shop?
Ask for recommendations from other trailer owners, mechanics, or your local trailer dealership. Look for shops with experienced technicians, specialized alignment equipment, and positive customer reviews.
By understanding the importance of tandem axle alignment, performing regular inspections, and addressing any issues promptly, you can ensure safe and efficient towing, extend the life of your tires and trailer components, and avoid costly repairs down the road.