The Von Duprin 900424 is the OEM mounting package for thick doors in the 2-1/4" to 2-3/4" thickness range, covering the Von Duprin 70 Series and 98/99 Series exit devices. It ships the sex bolts, mounting screws, and associated hardware sized specifically for this door thickness window. Compatible across the 78 Rim, 78-F fire-rated Rim, 7827 SVR, 7827-F SVR, 7847 CVR, 7847-F CVR, 7847 WDC, and 7847-F WDC, as well as the 98/99 Rim and 98/9927-F SVR device series. Per the Von Duprin 70 Series Parts Manual (Allegion document 116131), this is the thick-door mounting package - ordered in place of the standard mounting package (900561) when the installed door thickness falls between 2-1/4" and 2-3/4".

Getting the mounting package thickness right is not optional. Wrong-length sex bolts mean either a device that's loose on the door (too short) or bolts that bottom out before clamping the device tight (too long). Measure the door first. If it falls within 2-1/4" to 2-3/4", this is the correct package.

Von Duprin 98 Mounting: Why Thick Doors Need a Different Package

Standard Von Duprin exit device installations assume 1-3/4" hollow metal doors - the most common commercial door thickness. The standard mounting package (900561, covering 1-3/4" to 2-1/4") is the default for most jobs. Thicker doors show up in specific construction types: solid wood doors with stiles and rails, steel-core security doors, lead-lined doors in healthcare and imaging facilities, blast-resistant doors in government buildings, and some storefront aluminum doors with thicker profiles.

For any door in the 2-1/4" to 2-3/4" range, the sex bolts from the standard package won't reach through cleanly. The device attaches at four points through the center case - each point requires a sex bolt that spans the full door thickness and leaves enough thread engagement on both sides to properly clamp the device. The 900424 provides sex bolts sized for the 2-1/4" to 2-3/4" window, which is the next thickness step up from the standard package.

Von Duprin Mounting Package: 70 Series and 98/99 Series Compatibility

The 900424 works across two major Von Duprin product lines.

The Von Duprin 70 Series includes the 78 Wide Stile Rim device, the 7827 Surface Vertical Rod device, and the 7847 Concealed Vertical Rod device - all available in both standard panic (P) and fire-rated (F) configurations. The 70 Series is Von Duprin's architectural product line, designed for high-traffic commercial and institutional applications where a cleaner aesthetic is specified alongside Grade 1 performance.

The 98/99 Series is Von Duprin's heavy-duty institutional line - the 98 has a smooth mechanism case, the 99 has a grooved case, and both are available in rim and SVR configurations. The 98/9927-F is the fire-rated SVR version. The same mounting hole pattern and sex bolt geometry that serves the 70 Series thick-door application applies to these 98/99 devices as well, which is why the 900424 covers both product lines from a single part number.

Von Duprin Exit Device Parts: 900424 vs 900561

The mounting package family for the 78/7827/7847 and 98/99 Series covers two door thickness ranges. The 900561 is for 1-3/4" to 2-1/4" thick doors. The 900424 (this product) is for 2-1/4" to 2-3/4" thick doors.

The dividing line is 2-1/4". A door exactly at 2-1/4" sits at the top end of the 900561 range and the bottom end of the 900424 range. In practice, if the door is right at the borderline, measure carefully and confirm which package length gives full thread engagement without the sex bolt protruding past the door face.

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