The sections where the slave lever brackets are secured do not have sufficient strength, and they may crack from repeated dry steering. If this problem is left unattended, the cracks may grow, causing the sleeve levers to be unstable. In such a case, misalignment of the neutral position of the steering wheel may occur and/or the vehicle may drift while the driver has an intention of driving straight, and in the worst case, the slave levers could separate from the vehicle frame, which would make steering impossible.