CB400F Frame Bracing

Common study data

     Material - Plain carbon steel
     Braking Loads - 1200lbs upward on lower bearing race face
     8400 lbs opposing on each of the upper and lower bearing race faces, normal to a plane passing axially along the steering axis.

Torsion Loads - 1200lbs upward on lower bearing race face
5000 lbs opposing on each of the upper and lower bearing race faces, normal to a plane passing axially along the centerline of the bike.

Study #1 - Stock CB400F - There is more deflection shown here than in the previous frame study. I re-measured and re-modeled many of the frame components in this study to be more accurate, and changed the material from AISI 1020 to plain carbon steel.

Braking Mode

Torsion Mode

FEA1 - Side bracing

Braking Mode

Torsion Mode

FEA 2 - Side Bracing and Shock Mount Bracing

Braking Mode

Torsion Mode

FEA 3 - Side bracing and Suspension Bracing

Braking Mode

Torsion Mode

FEA 4 - Side, Swingarm, and Shock Bracing

Braking Mode

Torsion Mode

FEA 5 - Side, Swingarm, and Shock Bracing

Braking Mode

Torsion Mode

FEA 6 - "Boxed" spine.

Someone on one of the forums had questioned me about boxing the spine of the frame. Round tube is stiffer torsionally than square, so I looked at adding an extra 2" dia. spine to the frame. The results are a little misleading, because the deflection numbers are worst than for the stock frame. But I also included the stress plots for this version, and the stock frame, below. Have a close look and you can see that the stiffer spine has moved the stresses to other, more flexible areas, resulting in more displacement at the head.

Braking Mode