One problem related to ball joint has been reported for the 2013 Jeep Wrangler. The most recently reported issues are listed below.
When vehicle hits a bump, it vibrates so driver is unable to control vehicle until it is brought to a complete stop. Investigation online points to "death wobble" as described by other Jeep owners. Happens on both city streets and highway. Took to local Jeep dealership, replaced ball joints, happened again a week later. Called dealership again, they don't seem to have an answer for us. Literally afraid to drive vehicle without a definite fix or answer.