Telescopic shaft for motor vehicle steering

A telescopic shaft for vehicle steering, comprising:

• a male shaft formed with first and second axis-directional grooves extending in an axis-direction on an outer peripheral surface at an interval of a predetermined angle;
• a female shaft disposed coaxially with said male shaft, formed with third and fourth axis-directional grooves extending in the axis-direction on an inner peripheral surface in correspondence with said first and second axis-directional grooves, and fitted onto said male shaft;
• a first torque transferring member interposed between said first axis-directional groove of said male shaft and said third axis-directional groove of said female shaft;
• an elastic member interposed between said first torque transferring member and said first axis-directional groove of said male shaft, and extending in the axis-direction;
• and
• a second torque transferring member interposed between said second axis-directional groove of said male shaft and said fourth axis-directional groove of said female shaft;
• said telescopic shaft being assembled in a steering shaft of a vehicle and constructed by fitting said male shaft and said female shaft to each other so as to be capable of transmitting torque therebetween and moving axially relative to each other,
• wherein said elastic member is integrally formed with a first contact portion at which the elastic member is in contact with said first torque transferring member, a second contact portion at which said elastic member is in contact with said groove surface of the male shaft, and a biasing portion which connects said first and second contact portions and elastically holds said first and second contact portions to be spaced apart from each other so as to apply a preload via said first and the second contacting portions, and
• the preload caused by said biasing member is so set not to exceed a tolerance value of a surface pressure at said first contact portion against said first torque transferring member.