Yamaha Technology 1985: Aluminum Deltabox Frame

 

A high-rigidity aluminum frame construction that helps achieve outstanding handling stability. Adopted first on the ’85 model “TZR250”. Since then it has been adopted on important supersport models. The further evolved Deltabox frame now appears on the “R” series models.

Summary of the Mechanism
This frame was developed as a further evolution of the conventional steel pipe double cradle frame to
achieve the high rigidity necessary to mount a high-performance engine on a supersport model. Its design was based on technologies garnered from the YZR500 GP competition machines. It is characterized particularly by its light weight and high rigidity made possible by the use of aluminum, enabling a 40% weight reduction compared to a conventional steel pipe frame.

Development Aim
The “TZR250” was developed with the aim of bringing the feeling and riding characteristics of the fabled YZR factory machines to a production model. The Aluminum Deltabox frame was an important design point in realizing this goal.

Structure and Function 
The frame adopts a box-shaped cross-section that enables a larger cross-section surface area, lighter weight and high rigidity. Of particular note in the design is the structure by which the steering head and the pivot point are connected in as straight a line as possible and the fact that a special construction technique is used to give a triangular shape (delta) to the side surface to achieve outstanding rigidity. Another exterior characteristic is the added width that is given to the steering head area where particular stress comes to bear during riding.

Effect 
1) Thanks to the weight reduction (a dry weight of 126kg was made possible on the TZR250) outstanding handling was achieved.
2) The lightweight, high-rigidity chassis helped achieve high-level performance in the basis functions of “running, turning and stopping”.
3) Outstanding steering stability and nimble handling were also achieved.