Shimano Motor Service
Why Service?
A lack of regular service, combined with moisture intrusion, can cause a range of issues that lead e-bike motors to throw error codes. Old grease often results in overheating, while water exposure accelerates bearing wear. As bearings wear down, torque and Hall effect sensors can begin to fail—eventually leading to serious gear damage and costly repairs if left unchecked.
You wouldn’t expect a bottom bracket to last for thousands of miles without maintenance, yet many riders assume these motors can run indefinitely without service. In reality, regular rebuilds are essential to keep them running smoothly and reliably. A rebuild is also far more economical than replacing the motor—since replacement often requires a complete new wiring harness, controls, and even a battery.
Sensor issues
The main drive shaft contains several permanently bonded sensors that are critical to motor performance. Excessive bearing play can cause these sensors to trigger error codes, while dirt and contamination buildup can damage these finely tuned systems—leading to costly repairs if not addressed early.
Internal transmission issues
Inside the motor, the gearing system combines both metal and plastic gears along with two Sprag clutches. Excessive bearing wear, dirt, and contamination can cause these gears to wear out prematurely, while old grease can lead to clutch slippage.
When rebuilding, we go beyond factory standards—using a special upgraded Sprag bearing grease for smoother performance and longer-lasting reliability, along with a specialized electronic-safe gear grease engineered specifically to handle the extreme forces these motors produce.
Complete overhaul
When servicing these motors, we begin with a complete cleaning and inspection to ensure the unit is fit for a rebuild. Using Shimano’s diagnostic software, we thoroughly evaluate and diagnose the motor before proceeding.
Every component is then fully re-greased with three specialized greases, each chosen for its specific function. Next, we replace all bearings with sealed bearings—a major upgrade over the non-sealed factory versions. In critical locations, we go even further by installing stainless steel and ABEC-5 precision bearings, delivering superior performance, durability, and long-term reliability.
Testing
We fully evaluate and bench-test every motor bothbefore and after each repairusing Shimano diagnostic software. To ensure accuracy, we’ve designed and machinedcustom in-house tooling and fixturesspecifically for working on and testing these motors. By using known-good components in our test setups, we can precisely identify the source of issues and guarantee reliable repairs.