well at each joint of the suspension that moves ther are bushings, which are normally made of rubber that go in between the joints to help create a little flex and absorb the conditions in the road as the suspension pieces travel and the car moves. these bushings can fail as rubber will dry out after time or become worn, but can also create noises when they are rubbed or twisted as the suspension parts move.. rubber was typically used for its softness and that it didnt create much noise, so im not sure why yours would, but its possible.. mine squeak considerably, but it is because i had all mine replaced on the entire car with aftermarket ones that are made from urethane which is a harder material that resists flex, but tend to squeak mainly when its really cold.