The Comprehensive Guide to Drive Shaft U-Joints: Measurements, Identification, and Replacement

The drive shaft u-joint, also known as a universal joint or cardan joint, is a crucial component in the drivetrain of vehicles, allowing for the transfer of power from the transmission to the wheels while accommodating for changes in angle between the two. Understanding the size and specifications of a u-joint is essential for proper fitment and function, as measurements such as the width over the caps and the distance between bolt holes/cap diameter are used to classify the size.

Measuring and Identifying Drive Shaft U-Joints

Width Over the Caps

The width over the caps, measured from the outside edges of the two caps on the u-joint, is a key identifier of the joint’s size. The RPL u-joint series, for example, classifies the size based on this measurement, with a 2.75-inch width over the caps indicating a size 1310 joint. Other common u-joint sizes and their corresponding width over the caps measurements include:

U-Joint Size Width Over Caps
1310 2.75 inches
1330 3.19 inches
1350 3.63 inches
1410 4.00 inches
1480 4.50 inches

Distance Between Bolt Holes/Cap Diameter

Another crucial measurement for u-joint identification is the distance between the bolt holes or the diameter of the caps. This measurement, combined with the width over the caps, helps determine the correct u-joint size for a specific application. Some common u-joint cap diameters include:

  • 1310 series: 1.19 inches
  • 1330 series: 1.38 inches
  • 1350 series: 1.50 inches
  • 1410 series: 1.75 inches
  • 1480 series: 2.00 inches

U-Joint Kit Options

Once the driveshaft series has been determined using a tool like the Spicer Yoke Ruler, the appropriate u-joint kit options can be identified. For instance, a 1310 series driveshaft would correspond to u-joint kit options such as:

  • 5-153X for greaseable Spicer service kits
  • SPL140X for Spicer Life Series OE kits

Dimensional Charts

To accurately measure u-joints, using a caliper or micrometer in conjunction with dimensional charts is recommended. These charts, found in resources like Spicer’s K350 catalog, provide specific measurements for various u-joint types, allowing for precise identification and selection of the correct u-joint kit.

Replacing Drive Shaft U-Joints

drive shaft u joint

Removal and Installation

When replacing a u-joint, it’s important to follow the manufacturer’s instructions carefully. This typically involves the following steps:

  1. Secure the driveshaft to prevent it from falling during the u-joint removal process.
  2. Use a u-joint removal tool to press out the old u-joint from the yoke.
  3. Clean the yoke bore and inspect for any damage or wear.
  4. Apply a thin layer of high-quality grease to the new u-joint’s bearing cups.
  5. Press the new u-joint into the yoke using the appropriate tool, ensuring proper alignment.
  6. Secure the u-joint in place with the retaining clips or bolts.
  7. Grease the u-joint through the zerk fittings, if present.

Torque Specifications

Proper torque is crucial for ensuring the u-joint is securely installed and to prevent premature failure. Refer to the manufacturer’s recommended torque specifications for the specific u-joint being installed. As a general guideline, the following torque ranges are commonly used:

  • U-joint cap bolts: 35-45 ft-lbs
  • U-joint bearing cup retaining clips: 15-25 ft-lbs

Lubrication and Maintenance

Regular lubrication and maintenance of the u-joint are essential for its longevity and proper function. Most u-joints are equipped with zerk fittings, allowing for easy greasing. Follow the manufacturer’s recommended greasing intervals, typically every 3,000-6,000 miles or as specified in the vehicle’s maintenance schedule.

Conclusion

By understanding the key measurements, identification methods, and proper replacement procedures for drive shaft u-joints, you can ensure the safe and reliable operation of your vehicle’s drivetrain. Remember to always refer to the manufacturer’s instructions and use the appropriate tools and torque specifications to ensure a successful u-joint replacement.

References

  • ScienceDirect, “Study of the workspace of a class of universal joints,” 2022.
  • Action Machine Inc, “RPL U-Joint Identifier,” 2023.
  • Dana Media Library, “[PDF] Spicer® Yoke and U-Joint Measurement,” 2020.
  • Spicer Parts, “Measuring U-Joints.”
  • YouTube, “UNKNOWN U-Joint???? How to measure universal joints,” 2021.
  • Dana EZ-ID User Guide, “Identifying Driveshaft Assemblies – Even Without Part Numbers.”