The Von Duprin 900390 is the OEM tailpiece mounting package for the Von Duprin 940 Series lever trim, compatible with 98/99 Series exit devices. The package ships are non-finished - the tailpiece and mounting hardware are internal components housed within the door and trim, not visible on the door face, so no finish specification is required. This is a stocked part, available without a lead time.

The tailpiece mounting package provides the hardware set needed to properly seat, guide, and retain the tailpiece assembly within the 940 trim installation. Ordering the 900390 as a standalone replacement covers trim service calls where the tailpiece hardware has worn, broken, or been lost during a door modification - without requiring a full 940 trim replacement.

What the Von Duprin 940 Series Trim Is

The 940 is one of Von Duprin's lever exit device trim series for the 98/99 platform. It provides outside lever access on 98/99 Series devices and is available in a variety of lever styles to match architectural specifications. The 940 fits the functional role of an outside trim: it mounts on the exterior face of the door, provides a lever handle for authorized outside users, and integrates a mortise cylinder that keys into the exit device's inside mechanism through the door.

The 940 is distinct from the 996 lever trim and the 990 trim in specific applications and lever aesthetic options. All three serve the 98/99 Series family but carry different lever profile options and mounting configurations. The tailpiece system is specific to each trim series - the 900390 is for the 940 Series only.

Von Duprin Tailpiece Mounting: What the Tailpiece Does

In a Von Duprin exit device trim installation, the tailpiece is the steel interface bar that runs from the back of the mortise cylinder through the door to the exit device's inside locking mechanism. When the correct key is inserted into the outside cylinder and turned, the cylinder plug rotates and drives the tailpiece. The tailpiece rotation transmits that key input through the door thickness and engages the exit device mechanism on the push-bar side of the door.

The specific result depends on the trim function installed. On a classroom trim, key rotation locks or unlocks the inside push bar. On a storeroom trim, the key always controls outside entry while the inside lever remains free. On a night latch trim, key rotation retracts the latch bolt only. In all cases, the tailpiece is the physical link that makes the outside key work.

The mounting package for the tailpiece (900390) provides the tailpiece guide - typically a nylon component that channels the steel tailpiece through the trim and prevents metal-to-metal wear as the tailpiece rotates during key operation. The guide also maintains tailpiece alignment through the door bore. A nylon pine tree clip or equivalent retention hardware retains the tailpiece guide in position within the mounting hole.

The tailpiece itself can be cut to length in the field to accommodate different door thicknesses - the Von Duprin 98/99 installation instruction explicitly covers this: "Install tailpiece guide. Cut tailpiece as needed." The 900390 mounting package provides the guide hardware that must be in place before the tailpiece is trimmed and seated.

Von Duprin Exit Device Parts: 940 Trim in the 98/99 Trim Family

The 98/99 Series supports multiple outside trim series - 940, 996, 990, and others - each with its own mounting hardware and tailpiece interface requirements. The 940 trim and the 900390 tailpiece mounting package are not interchangeable with 996 or 990 trim tailpiece hardware. If the trim installed on the door is not the 940 Series, the 900390 doesn't apply.