Underlever Damper System

With the introduction of the revolutionary Renner USA underlever system designed several years ago for the professional piano technician, it is now possible to completely replace both of the actions in most American grand pianos. The Renner USA Custom Damper Underlever System or Back Action Kit enables the professional piano technician to completely replace or retrofit the grand piano damper back action in many fine, vintage, American grand pianos. The kit is produced in component form which allows the action to be custom tailored to fit the many different grand piano scales produced over the past 150 years.
Underlever Damper System
The kit includes the underlever tray, the tray ending blocks, pivot pins, a complete set of underlevers, flange screws, the wire flange keeper, tray cushion felt, stop rail cushion felt, damper lever assist springs, and a roll of mylar tape for creating the template.

A special commercial grade, extended shank, drill bit is available for creating the flange screw holes, and will remain precision sharp for many underlever system replacements.

The Renner Back Action can be used to replace:

  • Early Steinway back actions that have been damaged or worn out.
  • Early back actions that require the conversion of plain-wood socket set screws to metal bushed socket screws.
  • Conversions of early underlever sets having a veneer sostenuto pick-up tab to a new spring activated pick-up tab.
  • Conversions of the later Teflon type back actions with the short-arm underlever.
  • Early bushed type short-arm underlevers that react poorly with the geometry required for back actions.