MaxTrac 411420 Leaf Spring Shackle Kit Instruction Manual

1. Product Overview

The MaxTrac 411420 Leaf Spring Shackle Kit is designed to lower the rear of a vehicle by approximately 2 inches. This kit features powder-coated grey shackles and includes greasable bushings and sleeves for enhanced durability and maintenance. MaxTrac specializes in suspension lift and lowering systems, utilizing advanced manufacturing processes to deliver bolt-on solutions for various vehicle applications.

Image: MaxTrac 411420 Leaf Spring Shackle Kit, showing two grey powder-coated shackles with red greasable bushings.

2. Safety Information

Always prioritize safety when working on a vehicle. Read all instructions thoroughly before beginning installation. If you are not confident in your mechanical abilities, seek professional installation.

• Wear appropriate personal protective equipment (PPE), including safety glasses and gloves.
• Ensure the vehicle is securely supported on jack stands on a level surface before working underneath it. Never rely solely on a jack.
• Disconnect the vehicle's battery before starting any electrical work, though this kit typically does not involve electrical components.
• Be aware of potential pinch points and hot components.
• Properly dispose of all waste materials.
• This product may contain chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm (Proposition 65 warning). Wash hands after handling.

3. Package Contents

Verify that all components are present and undamaged before beginning installation.

• Maxtrac 411420 Rear Lowering Shackles (Quantity: 2)
• Greasable Bushings and Sleeves (Pre-installed or separate, verify upon opening)
• Note: Additional hardware (e.g., bolts, nuts) may be required depending on vehicle specifics and condition of existing components.

4. Setup and Installation

This kit is designed for a 100% bolt-on installation, however, some vehicle applications may require minor modifications. Professional installation is recommended.

Required Tools (Typical):

• Floor Jack and Jack Stands
• Socket/Wrench Set (Metric and/or SAE, depending on vehicle)
• Torque Wrench
• Penetrating Lubricant
• Grinder or Saw (potentially for bed support modification on some F-150 models)
• Grease Gun (for greasable bushings)

Installation Steps (General Guide):

1. Prepare Vehicle: Park the vehicle on a level surface. Engage the parking brake. Loosen the rear lug nuts.
2. Lift Vehicle: Safely lift the rear of the vehicle using a floor jack and support it securely with jack stands under the frame, allowing the rear axle to hang freely. Remove the rear wheels.
3. Support Axle: Place a jack under the rear axle to support its weight.
4. Remove Old Shackles: Carefully remove the bolts securing the factory leaf spring shackles. This may require significant force and penetrating lubricant due to rust. Note the orientation of the original shackles.
5. Address Bed Support (if necessary): For certain vehicle models (e.g., some Ford F-150s), a section of the bed frame support may need to be cut to allow clearance for the new shackles and leaf spring movement. Measure and mark carefully before cutting.
6. Install New Shackles: Position the new MaxTrac lowering shackles. Ensure the greasable bushings are properly seated. Install the bolts, but do not fully tighten them yet.
7. Lower Axle and Torque: Slowly lower the vehicle's axle until the full weight is on the suspension. This allows the bushings to settle in their natural resting position. Torque all shackle bolts to the vehicle manufacturer's specifications. Refer to your vehicle's service manual for exact torque values.
8. Reinstall Wheels: Reinstall the rear wheels and torque the lug nuts to factory specifications.
9. Final Checks: Lower the vehicle completely. Bounce the rear of the vehicle several times to allow the suspension to settle. Visually inspect all installed components for proper fitment and clearance.

Important: An alignment is highly recommended after any suspension modification to ensure proper vehicle handling and tire wear.

5. Operating Considerations

After installing the lowering shackle kit, the vehicle's rear ride height will be reduced. This may affect handling characteristics, towing capacity, and clearance. Drive cautiously until you are accustomed to the new suspension feel.

• Ride Quality: The ride quality may change slightly.
• Clearance: Be mindful of reduced ground clearance, especially over speed bumps, driveways, and uneven terrain.
• Towing/Hauling: If the vehicle is used for towing or heavy hauling, consider auxiliary air bags or helper springs to maintain proper ride height and prevent bottoming out.

6. Maintenance

Regular maintenance of your MaxTrac lowering shackles will ensure longevity and optimal performance.

• Lubrication: The included greasable bushings require periodic lubrication. Use a high-quality chassis grease and a grease gun to lubricate the fittings every 3,000-5,000 miles or during every oil change, or as needed based on driving conditions.
• Inspection: Periodically inspect the shackles, bushings, and mounting hardware for any signs of wear, damage, or looseness. Tighten any loose bolts to factory specifications.
• Cleaning: Keep the shackles clean from excessive dirt and debris, especially around the bushings.

7. Troubleshooting

If you encounter issues after installation, consider the following common troubleshooting steps:

• Vibration After Installation:
  • Ensure all bolts are properly torqued.
  • Check driveshaft angles. Lowering the rear can sometimes alter the driveshaft angle, leading to vibrations. Driveline shims may be required to correct this.
  • Verify proper alignment.
• Not Achieving Advertised Drop:
  • Ensure the suspension has fully settled. Drive the vehicle for a short period and re-measure.
  • Confirm correct installation and orientation of the shackles.
  • Vehicle-specific factors (e.g., existing suspension wear, spring rate) can influence the final drop.
• Squeaking/Noises:
  • Lubricate the greasable bushings.
  • Check for any components rubbing or contacting the frame or other parts.

If issues persist, consult with a qualified automotive technician.

8. Specifications

9. Warranty and Support

Specific warranty information for the MaxTrac 411420 Leaf Spring Shackle Kit is typically provided by the manufacturer or the point of purchase. Please refer to the documentation included with your product or visit the official MaxTrac Suspension website for detailed warranty terms and conditions.

For technical support or inquiries regarding installation and product use, it is recommended to contact MaxTrac Suspension directly through their official channels.