Universal joints allow travel shafts to move along with the suspension as the shaft is definitely moving so power could be transmitted when the drive shaft isn’t in a straight line between your transmission and drive wheels.
Rear-wheel-drive vehicles own universal joints (or U-joints) 
at both ends of the travel shaft. U-joints hook up to yokes that also allow travel shafts to move fore and aft as automobiles go over bumps or dips in the street, which efficiently shortens or lengthens the shaft.
Front-drive vehicles also employ two joints, called frequent velocity (or CV) joints, but they are a different kind that also compensate for steering improvements.
On rear-drive vehicles, one signal of a donned U-join is a “clank” sound whenever a drive gear is involved. On front-drive automobiles, CV joints generally make a clicking noise when they’re donned. CV joints are covered by protective rubber boots, and if the boot footwear crack or are otherwise broken, the CV joints will lose their lubrication and be destroyed by dirt and wetness.
A U Joint U-joint is found in both front wheel drive and rear wheel travel cars. Although they are different in design, they possess the same purpose of giving the drive educate some flexibility. This is needed as all cars and trucks flex while in action.
U-joints are located on each of the ends of the trunk drive shaft, whereas CV-joints are found on front wheel travel vehicles. Each allows the travel shaft to rotate as the differential techniques in relation to the others of drive train attached on the chassis.
The U-joint functions to save lots of wear and tear on your vehicle’s transmission. Failure to have a universal joint substitute done when necessary can lead to substantial damage to your vehicle in the future.
There are some warning signs that U-joint or CV-joint is failing. They incorporate: