A 5-Step Guide

Step 1: Confirm the Need for a Double Cardan Shaft
This is the most critical step. A double Cardan shaft is not a standard coupling; it’s a specific solution.

• Choose a Double Cardan Shaft if you need:

  1. True Constant Velocity: To eliminate the speed and torque fluctuation inherent in a single universal joint.

  2. To Work at High Angles: It can operate efficiently at higher, more consistent angles (typically up to 30-40°) where a single joint would fail or cause excessive vibration.

• Primary Applications:

  • 4WD & Off-Road Vehicles: Connecting the transfer case to the front axle.

  • Lifted Vehicles & Trucks: Correcting driveline vibrations after suspension modifications.

  • Industrial Machinery: Connecting an engine or motor to a driven component where the shafts are at a significant, fixed angle.

  • Agricultural Equipment: PTO drives on uneven terrain.

  • Marine Propulsion: On certain inboard setups with angled shafts.

Step 2: Determine Key Application Parameters
Gather these specifications with high accuracy:

Step 3: Ensure Correct Phasing and Operating Angles
This is the unique, technical aspect of a double Cardan.

• Phasing is Mandatory: For the double joint to function as a Constant Velocity unit, the yokes on the center section (the “H” yoke) must be aligned in the same plane. Improper phasing will cause severe vibration.

• The “Near-Equal Angle” Rule: For optimal CV performance, the operating angle at the input end and the output end should be as close to equal as possible. A difference of more than 1-3 degrees can reintroduce vibrations.

Step 4: Select Specifications for Performance & Durability

• Torque Capacity: Select a shaft whose rated torque significantly exceeds your application’s maximum torque. A high safety factor is crucial for shock loads.

• Dynamic Balancing: For any application above idle speeds, the entire assembly must be precision-balanced. Unbalanced driveshafts are a primary cause of failure and vibration.

• Lubrication System:

  • Grease Fittings (Zerk Fittings): Allow for periodic maintenance. Common in automotive and industrial applications.

  • Sealed-for-Life: Pre-lubricated and sealed joints for maintenance-free operation in less demanding or hard-to-reach applications.

Step 5: Finalize with a Specialized Manufacturer or Supplier
Due to the complexity, choose a partner with proven expertise.

• Engineering Support: They should verify your angle, length, and torque calculations.

• Custom Manufacturing: They must be able to build a shaft to your exact length, with the correct yokes and splines for your application.

• Balancing Equipment: They must have the capability to dynamically balance the finished assembly.

Summary: Key Selection Criteria for Double Cardan Shafts

Final Recommendation: The selection of a Double Cardan Shaft is an engineering process. Provide the manufacturer with your working angles, torque, speed, required length, and connection details. They will use this data to design, build, and balance a shaft that is guaranteed to perform correctly in your specific application. Do not attempt to assemble one from mismatched components without expert guidance.