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Measure Twice, Bolt Once: The Importance of Accurate Rear Axle Measurements Before Purchasing U-Bolts

Measure Twice, Bolt Once: The Importance of Accurate Rear Axle Measurements Before Purchasing U-Bolts

Posted by Trekline Motorsports Tips on Oct 19th 2023

When it comes to upgrading your truck or SUV, precision matters. One critical area where this rule holds true is purchasing and installing U-bolts. U-bolts are key components of a vehicle's suspension system, designed to secure the leaf springs to the axle in the case of square U-bolts or to secure round bend U-bolts around the axle for round axle applications. A wrong-sized U-bolt not only puts stress on the suspension but can also affect the vehicle's handling and safety.

Measuring Your Rear Axle for Round Bend U-Bolts Using Calipers

If your vehicle has round bend U-bolts that secure around the axle, accurate measurements are crucial. Here's how you can use calipers for this purpose:

  1. Begin by cleaning the axle thoroughly. Any rust, dirt, or debris can distort your measurements.
  2. Open the caliper jaws wider than the axle diameter.
  3. Position the caliper across the center of the axle, making sure it's perpendicular to the axle. This ensures the caliper measures the widest point.
  4. Slowly close the jaws until they touch the axle's surface.
  5. Read the measurement on the caliper's digital display or scale. This measurement represents the diameter of your rear axle, which is vital for round bend U-bolts.

Square U-Bolts for Leaf Springs

However, not all vehicles use round bend U-bolts. Some trucks and SUVs utilize square U-bolts to secure the leaf springs to the axle. In this case, you won't need to measure the axle diameter since square U-bolts wrap around the leaf springs, not the axle itself.

Measuring Your Square U-Bolts

For vehicles with square U-bolts, focus on measuring the dimensions of the leaf springs and the distance between the U-bolt legs. This information is crucial for selecting the right square U-bolts to ensure a secure fit for your leaf springs.

Alternative Method for Round Bend U-Bolts without Calipers

If you don't have calipers, here's an alternative method for measuring round bend U-bolts using a piece of string and a ruler or measuring tape:

  1. Start by wrapping a piece of string around your clean, debris-free axle.
  2. Mark where the string overlaps with a pen or marker.
  3. Remove the string and lay it straight on a flat surface.
  4. Using a ruler or tape measure, measure the distance between the ends of the string. This gives you the circumference of the axle.
  5. To get the diameter, divide this measurement by 3.14 (pi). The result is the diameter of your axle, suitable for round bend U-bolts.

Remember, accurate measurements are key to finding the perfect U-bolt for your vehicle. Incorrect measurements can result in a poor fit, compromising the safety and performance of your vehicle.

Your adventure in customizing your truck or SUV begins with the details. And as an aftermarket automotive company, we're here to help every step of the way. So measure twice, bolt once, and enjoy the ride!