The Propshaft Needle Bearing, Mercury 30956T is a precision OEM replacement bearing manufactured by Koyo JTEKT, a global leader in high-performance bearing technology. This bearing is used in Mercury outboard gearcases to support the prop shaft inside the bearing carrier, ensuring smooth rotation, proper alignment, and long-term gearcase reliability.
 
Designed for a wide range of Mercury outboards, this Koyo needle bearing reduces friction and wear under high-load conditions commonly found in offshore, bass boat, and high-performance applications. It is commonly referred to as a Mercury bearing carrier needle bearing and is used across multiple engine families and horsepower ranges.
 
Fits Mercury Gearcases & Outboards
The Mercury 30956T needle bearing (Koyo OEM) is used in many Mercury and Mariner lower units, including standard gearcases, offshore gearcases, and performance applications.
 
Common Compatible Mercury Engines
This bearing is found in many Mercury V6 outboards, including:
V-135, V-140, V-150, V-175, V-200
XR2, XR4
XR-6 / Magnum III
V-150 HP (2.5L)
V-175 EFI (2.5L)
V-200 EFI (2.5L)
 
It is also widely used in larger displacement engines, including:
200 (3.0L EFI)
225 (3.0L EFI)
250 (3.0L EFI)
225 Marathon (3.0L Carb)
225 SeaPro (3.0L Carb)
3.0L EFI Marathon
3.0L EFI SeaPro
 
These engines are commonly used in commercial, recreational, and offshore marine applications, making this bearing a frequent service item in Mercury gearcases.
 
Broad Compatibility & Cross References
The Mercury 30956T propshaft bearing is used across a wide horsepower range, typically from 30 HP up to 250 HP, depending on gearcase design.
 
This bearing cross-references with several OEM and aftermarket part numbers, including:
30-30956
31-30956T
15265 series equivalents
Sierra 18-1158
GLM 11410
 
This broad compatibility makes it a common replacement for Mercury, Mariner, MerCruiser, and select Force outboards.
 
Koyo Engineered Performance
Manufactured by Koyo JTEKT, this bearing is built from hardened high-strength steel with precision-ground needle rollers designed to handle extreme axial and radial loads.
 
Koyo bearings are trusted in motorsports, automotive OEM, and marine applications for their durability, tight tolerances, and ability to perform under extreme conditions.
 
Inside the Mercury gearcase, this bearing:
Maintains precise prop shaft alignment
Reduces friction and heat buildup
Minimizes vibration and gear wear
Supports high-RPM operation in performance engines
 
Installation Notes
Proper installation is critical for long service life. The bearing carrier should be cleaned thoroughly before installation. The bearing must be pressed in using a bearing driver or hydraulic press, ensuring it seats evenly and squarely.
 
After installation, verify proper:
Carrier fitment
Prop shaft rotation
Preload and end play
 
Always follow Mercury service specifications to prevent premature wear or failure.
 
Why Replace the Mercury 30956T Bearing
A worn propshaft needle bearing can lead to:
Prop shaft misalignment
Increased vibration
Premature gear and seal wear
Reduced performance and efficiency
Replacing the bearing restores proper support inside the gearcase and helps prevent costly lower unit damage.
 
Built for High-Performance Mercury Applications
The Mercury 30956T Koyo needle bearing is designed for high-load, high-RPM marine environments, including saltwater and performance use.
 
Whether servicing a V-150, XR6, 200 EFI, 225 SeaPro, or 250 EFI outboard, this bearing delivers the durability and precision required to keep your Mercury gearcase running at peak performance.
 
Contact mike@buckshotracing77.com or +1-714-697-1716 with any questions.