I have bds front lower control arms and rear uppers with flex ends which I think are commonly refered to as johnny joints. My question is do these flex ends tend to make a knock of some sort during takeoff or reverse kinds like a quick metal on metal rub since it is metal on metal?

 

I have Curries with Johnnie Joints and no noise here. Is it kind of a clunk? Are you sure it's coming from the control arms?