# What is u-joint drive line?

## What is u-joint drive line?

A u-joint, or universal joint, is a component that connects the driveshaft to the differential, and sometimes connects the driveshaft to the transmission or two driveshafts to each other. It’s a cross shaped piece with a bearing at each end, that allows for lateral and side to side movement of the driveshaft.

## How are the you joints on a driveshaft identified?

Combination, conversion, cross-over u-joints connect mismatched driveshaft components. They can have a variety of series and snap rings needed to make the conversion. Different u-joints are identified by the measurements or “series” they are associated with.

What does an U-joint do in a car?

A u-joint allows for slight positions changed between the driveshaft, transmission, and differential. In other words; the driveshaft connects the transmission to the differential, but it can’t be a static, solid connection.

What happens if you have a bad U-joint?

A bad u-joint can also cause vibration at certain speeds, emanating from the center or rear of the vehicle. If a u-joint is excessively worn, there’s an easy test you can perform. With your foot on the brake, shift the car into reverse.

### What to do if your U-joint is worn?

If a u-joint is excessively worn, there’s an easy test you can perform. With your foot on the brake, shift the car into reverse. Then, shift into drive.

### What should the U-joint angle be on a drive shaft?

By using U-joints in pairs and in phase, and the angle between the driveshaft and the equipment at both ends is the same, the acceleration/deceleration cycles tend to cancel each other. These U-joint angles should always be at least 1-degree to avoid wearing out the yoke bearings.

What causes the U-joint of a drive shaft to squeak?

Since the bearing portion of each universal joint twists a small amount with each rotation of the driveshaft (but always in the same location) the grease can evaporate, or be thrown out of the bearing cup. The bearing becomes dry, metal-to-metal contact is made, and the u-joint bearings will squeak as the drive shaft rotates.

A u-joint allows for slight positions changed between the driveshaft, transmission, and differential. In other words; the driveshaft connects the transmission to the differential, but it can’t be a static, solid connection.

What happens when a universal joint breaks in a truck?

You’ve probably seen it before: a truck on the side of the road, with the drive shaft lying under the vehicle, no longer attached to the transmission or rear axle. This is the ultimate failure mode for a universal joint – literally breaking, and allowing the drive shaft to drop to the pavement, no longer transferring power.