Scooter shudders on take-off: CVT clutch and belt
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Applies to: BMW C400 GT/X and other CVT maxi-scooters
Symptoms
- Judder or shudder pulling away
- Slow acceleration from a stop
- Rattle from the transmission at low speed
Why it happens
The centrifugal clutch shoes glaze or wear unevenly, and worn variator rollers or a worn belt change the engagement.
How to fix it
- Remove the CVT cover and blow out belt and clutch dust.
- Measure belt width and roller diameter against the manual.
- Inspect the clutch shoes and bell; scuff glazed surfaces or replace.
- Replace worn rollers, belt and slider pieces as needed.
Tools and parts
- Clutch holding tool
- Drive belt
- Variator rollers
What the factory service manual covers
CVT: belt and roller wear limits, clutch service, torque specs. The full procedure, specs and wiring diagrams are in the factory service manual for your machine.