For the V rods that secure the rear axles of the vehicle with 4-bag type air spring suspension system onto the frame, the nuts securing the ball joints with the axles may loosen from transverse load occurred when the vehicle turns, because they do not have sufficient tightening strength. If the vehicle continues to be driven with such loose nuts, one of the nuts may fall off, causing the v rod and the axle to separate from each other, which would adversely affect the steering stability, and in the worst case, the axle might move sideways, causing the shock absorber to touch the tyre or the wheel. If the shock absorber is damaged and allows oil to leak, this could result in a fire.