Jounce bumpers and bump stops are hard foam and rubber parts that absorb sudden blows as a vehicle travels over potholes, curbs, and bumps in the road. They fit over strut inserts and shock absorbs. When the vehicle bottoms, they prevent the control arms and leaf springs from fully compressing metal to metal.
Replace jounce bumpers and bump stops whenever worn or missing. They dry out in time, requiring replacement, but unfortunately, they do not always come with replacement parts like strut inserts. Symptoms of missing and worn bump stops include noise and vibration caused by metal-to-metal contact.