Yokomo B9-RBTSA Rear Belt Tensioner Set for BD9  [B9-RBTSA]

Rear belt tensioner for BD9 chassis

The Yokomo B9-RBTSA rear belt tensioner is an RC-scale accessory designed to mount at the center bulk of BD9-style touring cars to stabilise the rear belt path. Its primary role is to suppress rear belt flapping that can lead to tooth skipping, keeping belt engagement consistent during acceleration and direction changes.

Compatibility is limited to the supported chassis listed below; the unit fits onto the centre bulk mounting area and works by maintaining a controlled belt angle and tension rather than changing belt length or drivetrain geometry. Because it acts directly on belt behaviour, the tensioner helps reduce intermittent drivetrain backlash that sometimes shows as skipped teeth under load.

Installation and tuning are straightforward: fit the tensioner to the centre bulk so the roller or contact point aligns with the belt run, confirm there is no rubbing on surrounding parts, then verify belt run under static and low-speed dynamic tests. Small adjustments to the tensioner position can remove slack or over-tensioning—observe belt wear and drivetrain feel after initial runs and re-check alignment periodically.

The part is intended for RC touring car use and should be treated as a maintenance or tuning item for improving belt stability on BD9 platforms.

Compatible Models

• MRTC-BD919
• MRTC-BD919S