Sierra 18-6401 U-Joint Assy Mc 864244A 2
Shipping (3PM)
Within 30 days
Sierra 18-6401 U-Joint Assy Mc 864244A 2 Product Description
Keep your boat's stern drive running smoothly with this precision-engineered U-joint assembly. Designed as a direct replacement for common wear items in marine propulsion systems, it restores power transfer efficiency and minimizes vibrations for a reliable on-water experience. Boat owners trust this component for its robust construction that stands up to saltwater exposure and high-torque demands.
Whether you're tackling routine maintenance or addressing driveline issues, this assembly ensures seamless integration with your existing setup. Its thoughtful design reduces downtime, letting you focus on what matters—enjoying time on the water.
Key Features and Performance Benefits
- Durable Construction: Built with high-grade materials resistant to corrosion and fatigue, ideal for harsh marine environments.
- Precision Fit: Engineered to OEM specifications for effortless installation without modifications.
- Smooth Operation: Needle-bearing design delivers low-friction performance, reducing heat buildup and extending service life.
- Vibration Reduction: Aligns perfectly to eliminate driveline shudder, improving ride quality and component longevity.
- Versatile Application: Suited for a range of inboard/outboard setups where reliable torque transmission is essential.
Why It Matters for Your Stern Drive
U-joints are the unsung heroes of your boat's powertrain, flexing to accommodate movement while transmitting engine power to the propeller. Over time, exposure to water, debris, and stress leads to wear—manifesting as clunking noises, loose steering, or uneven propulsion. Replacing with this quality assembly prevents cascading failures in gimbal bearings or couplings, saving you from costly repairs.
Perfect Fit for Popular Stern Drive Models
This U-joint assembly slots right into select stern drive configurations, matching the footprint of original equipment. It's a go-to choice for mechanics servicing multi-cylinder setups from the 1980s through early 1990s, ensuring compatibility without guesswork.
Common applications include Alpha One Generation II drives on inline-four, V6, and V8 powerheads. Always verify your drive serial number against manufacturer charts for the best match—pro tip: check the upper gearcase stamping for quick confirmation.
Installation Insights
- Drain gear lube and remove the drive from the transom.
- Disassemble the upper housing to access the old U-joint.
- Press out worn components and press in the new assembly, torquing to spec.
- Reassemble with fresh seals and refill lubricants.
- Test in neutral before trailering—listen for smooth shifts.
Tools needed: press arbor, snap ring pliers, and torque wrench. A service manual specific to your model accelerates the process.
Pro Tips for Long-Lasting Performance
To maximize the lifespan of your new U-joint:
- Inspect annually or every 100 hours of use for play or grease weeping.
- Use marine-grade grease during install and repack seals seasonally.
- Align the drive properly post-install to avoid binding.
- Monitor for early wear signs like metallic particles in gear oil.
Pairing with upgraded gimbal bearings enhances overall drivetrain reliability, especially in saltwater applications.
Frequently Asked Questions
What does a U-joint assembly do in a boat stern drive?
It connects the engine output shaft to the drive shaft, allowing flexible power transfer while compensating for angular movement between the powerhead and gearcase.
Is this U-joint a direct replacement for OEM parts?
Yes, it's engineered to OEM tolerances for a bolt-in fit, commonly cross-referencing high-wear marine drive components.
How do I know if my U-joint needs replacement?
Look for symptoms like vibration at idle, clunking during shifts, loose play in the driveshaft, or visible corrosion/rust on the joints.
Can I install this myself, or do I need a professional?
Experienced DIYers with marine tools can handle it in a few hours. Beginners should consult a certified tech to avoid misalignment.
What maintenance extends the life of this U-joint?
Regular greasing, proper alignment, and freshwater rinses after saltwater use keep it performing optimally for years.
Does it fit Gen I or only Gen II drives?
Primarily designed for Gen II configurations; confirm your drive model via serial number for Gen I compatibility.
Will this reduce vibrations in my boat?
Absolutely—its precision bearings and tight tolerances eliminate common sources of driveline shake when installed correctly.
Save $176 when you buy the Sierra 18-6401 U-Joint Assy Mc 864244A 2 for only $534 from NVN Marine! Same day shipping before 3pm.
Sierra 18-6401 U-Joint Assy Mc 864244A 2 Technical Specifications
| Type: | |
|---|---|
| Vendor: |
Sierra Engine Parts |
| Weight: |
10.94 lb |
Sierra 18-6401 U-Joint Assy Mc 864244A 2 User Reviews
Sierra 18-6401 U-Joint Assy Mc 864244A 2 Shipping & Return
| Shipping Weight: |
10.94 lb |
|---|---|
| Box Sizes: |
4.00 (h) x 4.00 (w) x 25.00 (l) |
| Cubic Feet: |
400.0 |
| Returnable: |
Yes |
For detailed shipping policy please check our Shipping Policy and you can find our Return and Refund Policy here.