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Required for fitment review to confirm compatibility.
The OBR Mercury 115 HP four-stroke lower unit is available as a new or remanufactured replacement gearcase for selected four-cylinder Mercury outboards. The available configurations cover 115 HP applications from 2001–2006 and selected 75 HP, 90 HP, and 115 HP four-stroke applications from 2007–2014.
Six application and shaft combinations are available in both conditions. The 2001–2003 group uses separate 20-inch L and 25-inch XL SKUs and is identified by the verified serial range 0T178500 through 0T800999. Separate OBR part numbers apply to the 2004–2006 and 2007–2014 generations.
Horsepower alone cannot confirm fitment. The engine serial number, model year, four-stroke configuration, and shaft length must match the selected SKU.
4-Stroke Optimized: Tailored to the power curves of the 2001–2003 115 HP 4-cylinder series.
Rugged Performance: Built with high-strength alloys to ensure maximum longevity in both fresh and saltwater.
Direct Fitment: Precision-machined to OEM standards for a seamless installation without modifications.
How Your Order Is Prepared for Shipping
Before dispatch, your order is carefully prepared to help ensure it arrives safely and in the expected condition.
Please inspect the package immediately after delivery. If the carton or product shows visible damage, take clear photographs before installation and contact Mariners Warehouse promptly.
| Specification | OBR Mercury 4-Stroke Lower Unit | 115 HP 2001–2006 & 75–115 HP 2007–2014 |
|---|---|
| Manufacturer / Brand | OBR Parts |
| Compatible Engine Make | Mercury |
| Product Type | Replacement outboard lower unit / gearcase |
| Engine Architecture | Four-cylinder four-stroke |
| 2001–2003 Application | Mercury 115 HP four-stroke; serial range 0T178500–0T800999 |
| 2004–2006 Application | Mercury 115 HP four-stroke |
| 2007–2014 Application | Selected Mercury 75 HP, 90 HP and 115 HP four-stroke outboards |
| Condition Options | New and remanufactured |
| Shaft Length Options | 20-inch L and 25-inch XL |
| Rotation / Configuration | Standard configuration; verify using the complete engine serial number |
| Gear Ratio | 2.07:1 for verified 115 HP applications; VERIFY BEFORE PUBLISHING for 75/90 HP 2007–2014 SKUs |
| New 2001–2003 SKUs | ME-G4-06-N for 20-inch L and ME-G4-06A-N for 25-inch XL |
| Remanufactured 2001–2003 SKUs | ME-G4-06-R for 20-inch L and ME-G4-06A-R for 25-inch XL |
| New 2004–2006 SKUs | ME-G4-07-N for 20-inch L and ME-G4-07A-N for 25-inch XL |
| Remanufactured 2004–2006 SKUs | ME-G4-07-R for 20-inch L and ME-G4-07A-R for 25-inch XL |
| New 2007–2014 SKUs | ME-G4-07B-N for 20-inch L and ME-G4-07C-N for 25-inch XL |
| Remanufactured 2007–2014 SKUs | ME-G4-07B-R for 20-inch L and ME-G4-07C-R for 25-inch XL |
| Major Exclusions | Mercury two-stroke, Optimax/DFI, Command Thrust, Pro XS, counter-rotation and unmatched shift-rod applications |
| Required Fitment Information | Complete Mercury engine serial number, horsepower, model year, engine type and existing shaft length |
| Supplier Warranty | 24 months; warranty terms apply |
| Core Charge | VERIFY BEFORE PUBLISHING with Mariners Warehouse operations |
A Mercury 115 HP four-stroke lower unit must match more than the horsepower shown on the engine cowling. Mercury used different configurations across the 2001–2003, 2004–2006 and 2007–2014 production groups, so model year, shaft length and engine serial number must all be checked.
For 2001–2003 Mercury 115 HP outboards, the 20-inch L application uses the ME-G4-06 family, while the 25-inch XL application uses ME-G4-06A. Separate ME-G4-07 and ME-G4-07A configurations cover applicable 2004–2006 115 HP engines. Selected 75 HP, 90 HP and 115 HP four-strokes from 2007–2014 use the ME-G4-07B or ME-G4-07C families, depending on shaft length.
New and remanufactured gearcases share the same stated application within each SKU family, but their condition and part numbers differ. Before ordering, locate the complete Mercury serial number and confirm whether the existing installation uses a 20-inch or 25-inch shaft. Do not substitute an Optimax, Command Thrust, Pro XS or counter-rotation gearcase based only on horsepower.
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The product information made it easy to confirm that this OBR unit matched my 2005 Mercury 115 HP 4-stroke. The 2.07:1 ratio, 20-inch shaft length, and serial-number checks were clearly detailed. Always verify your gear ratio before purchasing.
I appreciated that the OBR 75-115 HP 4-stroke lower unit options clearly distinguished between early Yamaha-based powerheads and later Mercury models. Mariners Warehouse confirmed fitment for my 2011 90 HP 4-stroke prior to shipping.
The unit arrived well-secured in a heavy foam-lined box. The drive shaft splines, water pump housing, and 20-inch shaft aligned perfectly on my 2012 115 HP outboard. Runs smoothly after completing the required break-in hours.
Matching the 2.07:1 gear ratio and engine year range was simple. The gearcase functions great on the water, though unbolting the protective shipping bracket took a bit of extra effort during installation.
Replaced a damaged gearcase on my 2008 75 HP 4-stroke. The listing clearly outlined the shaft length options and fitment warnings. After filling with high-performance gear lube, it has run without any issues.
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