The way I understand it, its for handling.

Two equal legnth A-arms create a paralleligram. This keeps the camber of the wheels constant. This gives you a flat foot print on the tire at all times. This is great for heavy travel suspensions (long travel) with vehicles that go in straight lines (dune buggies are a good example).

Unequal A-arms are able creat a camber efffect when turning right // or left \\. This gives better traction thru a turn and better handleing.

Well thats the way I understand it <img src="/forums/images/graemlins/scared.gif" alt="" />

Scott F.