Description

The Mercury MerCruiser Quicksilver 15-45691A1 is a genuine Mercury Marine OEM shim set used for select vintage MerCruiser gear housing service applications. This shim set is used to adjust the installed position of the driveshaft bearing cup within the gear housing, helping establish the correct gear alignment, bearing preload, and gear tooth contact pattern during lower-unit service. It should be used only where the MerCruiser gear housing diagram or service procedure specifically calls for 45691A1 / 15-45691A1.

Key Features

• Genuine Mercury Marine factory OEM shim set.
• Mercury/MerCruiser part number: 15-45691A1.
• Manufacturer part number: 45691A1.
• GTIN/UPC: 745061153011.
• Used for driveshaft bearing cup and gear housing shimming service where specified.
• Shim thicknesses commonly associated with this set include 0.002 in., 0.003 in., 0.005 in., and 0.010 in.
• Helps fine-tune bearing cup position, gear mesh, and internal tolerance setup during gearcase service.
• Intended for precision service work, not general hardware spacing.

Application Compatibility

Common application context includes select vintage MerCruiser sterndrive gear housing assemblies by serial number and service diagram, including:

• MerCruiser Model 90 Renault 96 I/L4 applications where specified
• Early 1970–1972 inline 4-cylinder MerCruiser drive configurations where the gear housing service procedure calls for this shim set
• Driveshaft bearing cup-to-gear housing shim locations requiring 15-45691A1 / 45691A1

Use this shim set only where the MerCruiser lower-unit or gear housing parts diagram specifically calls for 15-45691A1.

Fitment Notice

Confirm fitment by drive model, serial number, gear housing assembly, bearing cup location, and exact MerCruiser service procedure before ordering. Gearcase shims are selected by measurement, preload, and gear contact requirements; they should not be chosen by outside diameter or general appearance alone.

When This Part Needs Replacement

Replace or install this shim set during gearcase teardown when the original shim stack is missing, damaged, corroded, distorted, or no longer produces the correct bearing preload or gear tooth pattern. Shims may also be required when replacing the driveshaft bearing cup, gear housing, bearing components, gearset, or related lower-unit internal parts.

Installation Notes

Measure the existing shim stack before disassembly when possible and keep original shim locations organized. Final shim thickness must be selected according to the MerCruiser service manual using the correct measuring tools and gearcase setup procedure. Do not guess shim thickness. Incorrect shimming can cause noisy operation, poor gear contact, overheating, accelerated bearing wear, or gear failure.

Alternate/Superseded Part Numbers

• 15-45691A1 — Mercury/MerCruiser formatted part number
• 45691A1 — Manufacturer part number
• Sierra 18-2283 — aftermarket cross-reference; verify by application
• GLM 23260 — aftermarket cross-reference; verify by application

Parts Desk Insight

Shim sets are precision setup parts, not simple replacement washers. The correct combination of shim thicknesses determines gear alignment and bearing preload, so this kit should be installed as part of a measured gearcase setup procedure rather than by matching the old stack blindly.

Shipping: Ships same or next day for fast Canada wide shipping.