Constant velocity joint provided with grease retainer

A constant velocity joint comprising:

• an outer race provided with a first through-hole extending along a longitudinal axis and forming a plurality of outer ball grooves;
• an inner race provided with a second through-hole extending along a longitudinal axis and forming a plurality of inner ball grooves that are respectively pair with the outer ball grooves;
• a plurality of balls arranged respectively in a space formed by the pair of the outer ball grooves and the inner ball grooves;
• a ball cage that accommodates the plurality of balls;
• a first grease retainer coupled to the outer race to block the first through-hole in order to prevent grease filled into a space where the balls and the ball cage are placed from leaking out;
• and
• a second grease retainer coupled to the inner race to block the second through-hole in order to prevent grease filled into a space where the balls and the ball cage are placed from leaking out,
• wherein the grease retainer has a convex shape protruding towards the ball and the ball cage.