To replace and repair a leaf spring without removing an auxiliary machine by arranging a work bar inserting through hole coaxially with a shackle pin in the auxiliary machine arranged in a shackle side part of a front suspension for connecting the leaf spring and a side rail.

A silenser 21 installed on a side rail 3 between a fuel tank and a front wheel 5 is arranged on the side of a shackle 13 and a shackle pin 15 of a suspension. In this silencer 21, a work bar inserting through hole 41 for making a single pipe 39 penetrate through end plates 23, 25 and baffle plates 29, 31 on the inside/outside both sides, is arranged coaxially with the shackle pin 15. At replacing and repairing time of a leaf spring 9, a work bar 43 is inserted into the through hole 41 from the outside end plate 25 side, the tip part is applied to the shackle pin 15, and the base end part is struck by a hammer so that the shackle pin 15 is struck out in the A direction.