Original parts for YIKONG YK4106 Pro RC Car

Item name: Cup head hex socket screws M4*40 21152;

How do I know if Cup head hex socket screws need to be replaced?

• Appearance inspection: Check whether the screw surface has obvious cracks, deformation, serious corrosion or wear. If the screw head is severely worn, the hexagonal groove becomes smooth and difficult to tighten or loosen with tools, it may need to be replaced.
  
  
• Loosening: Check whether the screws are loose. If it is still loose despite normal tightening and fails to provide a solid connection, it may mean that the thread of the screw has been damaged and needs to be replaced.
  
  
• Force situation: If the screw breaks or bends when it is subjected to normal working stress, it indicates that its strength is insufficient and needs to be replaced.
  
  
• Degree of corrosion: If the screw is seriously corroded, affecting its structural strength and connection performance, it should be considered for replacement.
  
  
• Compare standard dimensions: Measure the diameter, length and thread specifications of screws with standard gauges. If the size deviates significantly from the standard, affecting the installation and fastening effect, it may need to be replaced.

How to choose the right part? Please purchase according to the manual number, refer to the picture, if you have any questions, please contact us.