Mercury MerCruiser Quicksilver Gearcase Roller Bearing Shim Set 42637A1
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Mercury MerCruiser Quicksilver 15-42637A1 is a shim set used between the roller bearing and gear housing in select Mercury, Mariner, and MerCruiser gearcase assemblies. Current Mercury parts references list 42637A1 as a shim set, not a gasket, and show the latest superseding replacement as 8M0063267. This shim set is used to help establish correct bearing position and gear housing setup during lower-unit service.
Key Features
- Genuine Mercury / Quicksilver-style shim set reference
- Used at the roller bearing to gear housing location
- Supports correct gearcase bearing and housing setup
- OEM reference: 15-42637A1
- Current replacement reference: 8M0063267
- Catalog shipping reference shows approximately 0.02 lb with package dimensions around 2.50 in. x 2.50 in. x 0.25 in.
Engine Compatibility
This shim set is shown in Mercury parts references for a wide range of select Mercury and Mariner outboard gear housing applications, including various Magnum II, Magnum III, V-115 DFI 2.5L, V-135, and related V6 gearcase assemblies depending on serial number range. Broader cross-reference catalogs also associate this part family with select Mercury / Mariner / MerCruiser 65–225 HP gearcase applications, including MR, Alpha One, and Alpha One Gen II gear housing component groups.
Serial Number Fitment Notice
Gearcase shim fitment depends on the exact engine, drive, gear housing, bearing arrangement, rotation, and serial number range. Always confirm compatibility using the engine or drive serial number before ordering, especially where older part number 15-42637A1 has been replaced by 8M0063267.
When This Part Needs Replacement
Replace or verify this shim set during gear housing rebuilds, roller bearing service, gearcase setup, or when the original shims are damaged, missing, corroded, or no longer suitable for correct bearing preload and gear alignment.
Installation Notes
Gearcase shim selection is a precision setup step, not a general gasket replacement. Installation should follow the Mercury service manual procedure for the specific gear housing. Correct measurement, shim stack selection, bearing seating, and gearcase inspection are important for proper lower-unit operation.
Alternate / Superseded Part Numbers
- 15-42637A1
- 42637A1
- 15-8M0063267
- 8M0063267
- GLM 23210
- Sierra 18-2294
Parts Desk Insight
This part number is commonly mistaken for a gasket because it appears in lower-unit service diagrams near other sealing parts. The safer match is by gear housing diagram and serial number, since shims affect bearing and gearcase setup rather than sealing.
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Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
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