BD9 Rear Belt Tensioner Upgrade for Centre Bulk - Yokomo B9-RBTSA  [B9-RBTSA]

BD9 rear belt tensioner function and fit

The Yokomo B9-RBTSA rear belt tensioner is an RC touring car accessory engineered to mount at the centre bulk of BD9-style chassis to control the rear belt path. Its main purpose is to suppress belt flapping that can cause tooth skipping, keeping belt engagement consistent through acceleration and direction changes.

Fitment is specific to the supported models listed below; the unit secures to the centre bulk mounting area and works by guiding the belt angle and controlling local tension rather than altering belt length or overall drivetrain geometry. By acting directly at the belt run, the tensioner reduces intermittent backlash and the skipped-tooth symptoms seen under load.

Installation is simple: attach the tensioner to the centre bulk so the roller or contact surface follows the belt trajectory, ensure there is sufficient clearance from surrounding parts, then verify belt alignment during static checks and slow-speed testing. Small positional tweaks will remove slack or prevent over-tensioning—inspect belt wear and drivetrain behavior after initial runs and re-check alignment periodically.

This item is intended as a maintenance and tuning component for BD9 touring car drivetrains.

Compatible Models

• MRTC-BD919
• MRTC-BD919S