The scooter clutch sits on the rear pulley in the left drive case. It has three spring-held shoes with friction linings, and a metal bell (drum) that is connected to the rear wheel through the final drive gears.
What it does
At idle the springs hold the shoes inward, so the wheel does not turn. As engine speed rises, the shoes are thrown outward and grip the inside of the bell, driving the wheel. The linings wear thinner and can glaze. The bell can wear a groove or go out of round. Weak springs let the clutch grip too early.
Signs it is worn or failing
- Judder or shudder when pulling away: Scooter judders.
- Scooter creeps at idle or the wheel turns on the stand: Scooter creeps. Check idle speed first.
- Revs rise, slow pick-up: Scooter revs but accelerates slowly.
- Rattle or scraping: Noise from the drive case.
When to replace it
Replace the shoes when linings are worn below the limit in your manual, uneven, oily or glazed. Replace the bell if it is grooved, cracked, blue from heat or out of round. Fit new shoe springs with new shoes.
What to match when buying
- Make, model, year and engine size. Bell inside diameter and shoe size must match.
- Buy shoes, springs and bell together if the bell is worn.
- Clutch spring strength sets when the clutch bites; use standard springs unless you know why you are changing.
- Avoid shoes with loose or thin lining, or no maker marking.
Fitting notes
- The clutch nut needs a special holder and spanner; often a workshop job. See Check the scooter clutch and bell.
- Keep oil and grease off the linings and bell.
- Check the belt and rollers while it is open.