Steering U-Joints
Steering universal joints connect sections of a steering shaft or column, allowing the steering input to transfer through angled joints to the steering box or rack. They're specified by the shaft ends on each side of the joint, which need to match what's already on your steering shaft and the components either side of it.
Shaft ends come in a few forms: smooth bore, double D (DD), and various splined patterns (such as 3/4"-20, 3/4"-30, 3/4"-36, 3/4"-48 and 13/16"-36 spline). A joint might have the same end on both sides, like 3/4" smooth x 3/4" smooth, or mix two different ends, like 3/4"-48 spline x 3/4" smooth, to adapt between two different shaft types. There's also a joint made specifically for a Stiletto rack.
When choosing a replacement or adding a joint to a steering shaft, match each end's size and style (smooth, DD or the specific spline count) to what it needs to connect to on your car.
Frequently asked questions
How do I choose the right steering U-joint?
Match each end of the joint to what it connects to on your steering shaft or column. This means checking whether each side needs to be smooth bore, double D (DD), or a specific spline pattern (such as 3/4"-36 or 3/4"-48 spline).
Can a U-joint have two different ends?
Yes, many steering U-joints are made with a different fitting on each side, for example 3/4"-48 spline on one end and 3/4" smooth on the other, so they can adapt between two different shaft types.
What's the difference between smooth and DD (double D) shaft ends?
Smooth bore ends rely on a separate clamping method to lock onto the shaft, while double D (DD) ends have flat machined sides that key into a matching shaft shape for a more positive fit.
