Patent ID: 7631882

Claim:
A vehicle height adjustment device for a vehicle suspension system having a compression coil spring interposed between a wheel-side member carrying a wheel and a vehicle-body member, which regulates a position of a spring seat member abutting against an end portion of the spring, so as to adjust a vehicle height, comprising: an adjustment bolt which is rotatably supported by the wheel-side member or the vehicle-body member and which is able to be fixedly secured to the wheel-side member or the vehicle-body member; and the spring seat member provided with a recess with an internal thread formed therein, which threadedly engages with said bolt, wherein rotation of said spring seat member is limited by a component of the wheel-side member or the vehicle-body member for causing a relative displacement of said spring seat member in an axial direction of rotation of said bolt in accordance with rotation of the bolt, wherein said bolt is securely fastened to the wheel-side member or the vehicle-body member for fixing a position of said spring seat member, wherein said bolt has a large-diameter screw part which is inserted into the recess and which is provided with an external thread engageable with the internal thread of the recess; a shank with a relatively small diameter, which is integral with the large-diameter screw part and which is inserted through a through-hole formed in said wheel-side or vehicle-body member; a small-diameter screw part integrally connected to or continuous with the shank; and rotating tool engagement means integrally provided on an end portion of the small-diameter screw part, and wherein a boss portion having said through-hole is formed in said wheel-side or vehicle-body member, and the boss portion has a flat bearing surface abutting against a step formed in a transition between said large-diameter screw part and said small-diameter shank.