The Buckshot Racing #77 Mercury 88957T Reverse Gear Ball Bearing is a premium OEM-quality Koyo bearing manufactured in Japan for compatible Mercury Marine, Mariner, and Mercury Racing lower units.
 
This is not a generic economy bearing. Koyo is a recognized precision-bearing manufacturer, and this bearing is selected as a high-quality replacement for applications originally using Mercury 30-88957T, 88957T, and 88957A1.
 
The 88957T bearing is used to support the reverse gear inside the propeller-shaft gearcase assembly. Accurate bearing support is critical to maintaining reverse-gear alignment, smooth rotation, and proper operation of the lower-unit gear train.
 
Koyo Japan OEM-Quality Construction
 
Lower-unit bearings operate continuously in a demanding environment that combines high shaft speed, thrust loading, gear loading, vibration, and marine gear lubricant.
 
The Buckshot Racing #77 88957T replacement is manufactured by Koyo in Japan and provides the precision construction expected for performance and professional lower-unit service. It is an excellent choice for stock rebuilds, high-performance Mercury applications, and Mercury Racing gearcases where bearing quality should not be compromised.
 
Mercury 2.5L V6 Applications
 
The 88957T reverse gear bearing is used across a broad range of compatible Mercury 2.5 Liter V6 two-stroke lower units.
 
Applications include many 135 HP, 150 HP, 175 HP, 200 HP, and 225 HP Mercury and Mariner engines, along with selected XR, XRi, XR6, EFI, Pro Max, and Mercury Racing gearcases.
 
Performance applications include compatible gearcases used with the 200 Pro Max, 225 Pro Max, Mercury Racing 260 EFI and 280 ROS, as well as other 2.5L racing and high-performance combinations using the 88957-series reverse gear bearing.
 
Because many Mercury Racing engines have been fitted with different lower units over their service life, the actual gearcase configuration should always be used to confirm bearing fitment.
 
Mercury 3.0L V6 Applications
 
The same 88957T bearing family is also used extensively in compatible Mercury 3.0 Liter V6 gearcases.
 
Common applications include selected 200, 225, and 250 HP carbureted, EFI, and DFI engines, as well as performance models such as the 250XB, 225 Pro XS, 250 Pro XS, 225 Sport XS, 250 Sport XS, 250XS, 300 Pro Max, 300 Super Magnum, and 300X.
 
The bearing can be found in conventional fishing gearcases as well as selected FleetMaster, TorqueMaster, and SportMaster lower-unit configurations.
 
Mercury Racing 300XS 3.2L
 
The Mercury Racing 300XS is a 3.2 Liter DFI engine, and selected 300XS SportMaster and TorqueMaster gearcases also use the 88957T reverse gear ball bearing.
 
For this reason, the 88957T should accurately be described as covering selected 2.5L, 3.0L and 3.2L Mercury V6 lower units, rather than simply 2.5L and 3.0L applications.
 
SportMaster, TorqueMaster & Performance Gearcases
 
The Mercury 88957T reverse gear bearing is not exclusive to one gearcase design.
It appears in numerous Mercury production gearcases as well as selected SportMaster and TorqueMaster performance lower units. Different applications may use different gear ratios, reverse gears, propeller shafts, bearing carriers and internal shimming while still using the same reverse gear ball bearing.
 
For this reason, identify the bearing by the Mercury 88957T / 30-88957T part number and the actual gearcase parts diagram, not horsepower alone.
 
Cross-Reference Numbers
 
Mercury: 30-88957T, 88957T, 88957A1, 88957, 860081, 35914, 17927
Sierra: 18-1155
GLM: 21620
Mallory: 9-75114
Additional Interchange Numbers: 500391, 509431
 
These numbers are provided for identification and interchange purposes. Always confirm the bearing required for the specific lower unit before installation.
 
When to Replace the Reverse Gear Bearing
 
The reverse gear bearing should be carefully inspected whenever the lower unit is disassembled.
 
Replace the bearing if there is roughness when rotated, excessive radial or axial movement, corrosion, pitting, brinelling, damaged races, discoloration from heat or visible deterioration of the rolling elements.
 
If the lower unit has suffered a gear failure or produced significant metal contamination, replacing only the damaged gear is not enough.
 
The 88957T bearing and the other gearcase bearings should be inspected closely because metallic debris can quickly damage precision bearing surfaces.
 
Buckshot Racing #77 Lower Unit Tech Tip
 
During a gearcase rebuild, inspect the complete reverse-gear assembly, including the reverse gear, 88957T ball bearing, thrust components, bearing carrier, propeller shaft, and clutch dog.
 
Check the gear teeth for pitting or abnormal contact patterns and inspect the bearing surfaces for wear or fretting. Clean all metal contamination from the housing before reassembly.
 
Mercury gearcases require the correct bearing installation depth, shimming, gear backlash, and preload procedures for the specific lower-unit family. These settings should always be established using the appropriate Mercury service specifications and tools.
 
The Buckshot Racing #77 Koyo Japan 88957T Reverse Gear Ball Bearing provides an OEM-quality replacement for one of the most widely used reverse-gear bearings in classic and high-performance Mercury V6 lower units.
 
It is an excellent choice for professional rebuilds involving Mercury 2.5L, 3.0L, and 3.2L engines, Pro Max, 260 EFI, 280 ROS, 250XS, 300X, 300XS, SportMaster, and TorqueMaster gearcases where the 88957T bearing is specified.
 
Contact Mike Hill at +1-714-697-1716 for tech support.