Universal joints allow travel shafts to move along with the suspension while the shaft is normally 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 possess universal joints (or U-joints) at both ends of the travel shaft. U-joints hook up to yokes that also allow travel shafts to go fore and aft as U Joint automobiles go over bumps or dips in the road, which properly shortens or lengthens the shaft.
Front-drive vehicles also apply 
two joints, called frequent velocity (or CV) joints, but they are a different kind that also compensate for steering improvements.
On rear-travel vehicles, one sign of a donned U-join is a “clank” sound whenever a drive gear is involved. On front-drive cars, CV joints generally make a clicking sound when they’re worn. CV joints are included in protective rubber footwear, and if the boot footwear crack or are otherwise ruined, the CV joints will lose their lubrication and be damaged by dirt and moisture.
A U-joint is situated in both front wheel drive and rear wheel drive cars. Although they are different in design, they possess the same reason for giving the drive train some flexibility. This is necessary 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 drive vehicles. Each allows the drive shaft to rotate as the differential techniques in relation to the others of drive train mounted on the chassis.
The U-joint functions to save wear and tear on your vehicle’s transmission. Inability to have a universal joint substitute done when needed can result in substantial harm to your vehicle in the future.
Here are a few warning signs that U-joint or CV-joint is failing. They consist of:
