recently, i noticed a knocking noise from back of car when i back up the car. the noise is louder if the car is going down an inclined surface, ie drive way. it occurs only once when i start backing up. the car runs great otherwise. any good ideas about what could be going on?

 

I have the same thing like a creak sound only when in 1st gear and in Reverse but for a moment....Im taking my car to the dealer there is a Service Number 011201 like a Severce announcment for a fix so take it to the dealer something with the rear hub and spindle nut well good luck

 

retorque drivers side rear axle nut.