Shantou a user's Honda CH125 scooter, in a traffic accident after the wheel damaged. After the replacement of a new piece, the uniform speed is normal, as long as the vehicle accelerates, decelerates or bumps, the rear wheel will give out a different sound, when two people ride, the sound is greater.

In general, the fault is related to the vehicle transmission mechanism. Maintenance workers first support the vehicle, positive and negative direction idling rear wheel, no abnormal sound. Remove the rear reduction box of the scooter, check the gear group and drive shaft, and find no abnormality. Then the decomposition of transmission mechanism, incidentally check the vehicle and engine support connection and rear suspension device, failed. The site asked the maintenance station about the details of the replaced wheel hub, and answered that the rear wheel hub was imported through regular channels, so it was guaranteed that it was not fake parts.

Then, re-check the transmission parts and the engine speed change mechanism, and then test run, has not found the root of the abnormal sound of the rear wheel, the investigation into a deadlock.

Ask the maintenance personnel to remove the rear wheel hub of the broken car, carefully observe and accidentally find that the matching trace of the spline hole of the rear hub and the spline part of the output shaft of the rear gearbox is not normal. Comparing the spline holes of the rear hub in stock with the spline parts of the output shaft, it is found that there are obvious differences.

The specific differences are as follows: the spline pressure Angle of rear hub spline hole and output shaft of Honda original CH125 pedal is 37.5°, while the spline pressure Angle of rear hub and output shaft of Domestic imitation Honda 125 is 30°, as shown in the figure below. In this way, the maintenance station installed the domestic imitation Honda 125 rear wheel hub on the output shaft of the rear gearbox of Honda CH125 pedal, so that the spline hole of the rear hub did not match the meshing part of the spline of the output shaft of the rear gearbox, and the root of abnormal sound was here.

When the vehicle is traveling at a uniform speed, the output shaft and the rear hub hole run in the same direction, without relative movement, and are basically normal. Whenever the vehicle accelerates, decelerates or encounters bumpy road surface, the spline hole and spline shaft meshing part will produce relative movement and impact when the vehicle changes speed, so the abnormal sound will be emitted.

The problem finally came to light. I will faithfully inform and ask for the consent of the user to change the rear wheel hub and output shaft (as shown in the picture above) into domestic parts with pressure Angle of 30°. Carefully reinstall the rear wheel gear box combination, road test, whether acceleration, deceleration or bumpy road are not abnormal sound issued, confirm troubleshooting.