within the opposite threaded portion 42 of body 40 optionally lock nuts 48 are previously screwed on the eye bolts 44 and j bolts 46 before the latter are screwed within the body 40 the lock nuts are designed to be tightened against the end faces of body 40 the turnbuckle 38 once assembled is attached to the outer hook portion 36 of coil spring 32 by the eye bolt 44 while the j bolt 46 has its hook releasably inserted within the aperture 26 of the wiper bar 18 the inner end portion 24 of wiper bar 18 is bent away from the outer wall of the channel shaped wiper arm 14 so as to provide sufficient space for easy insertion of the j bolt 46 into the aperture 26 the turnbuckle 38 must be small enough to easily fit within the channel shaped wiper arm 14 with sufficient space between the side walls of the wiper arms and the body 40 of the turnbuckle for insertion of a conventional open end spanner to rotate the turnbuckle body in order to cause elongation or contraction of the coil spring and thus adjust its tension to obtain the optimal wiper blade pressure on windshield w once the desired pressure has been obtained the lock nuts 48 are tightened against the end faces of body 40 again by the use of a conventional open end spanner preferably the external diameters of.