MERCEDES Steering Gear Rack 551-50115 Benz Gear/rack 251

( Manufacturer Part Number: R500 ), ( Part Type: Steering Gear Rack ), ( Conditions Options: Core Value 95 ), ( Genuine Oem: Yes ), ( Ipn: 551-50115 ), ( Make: Mercedes-benz ), ( Year: 2007 ), ( Manufacturer Warranty: 90 Day )

Review MERCEDES benz Steering Gear/rack 251 Type R class fits R500 R320 2006–2008

The **Mercedes-Benz Steering Gear/Rack Assembly (Part Number: 551-50115)** is a precision-engineered component designed exclusively for the **R-Class (W221) models produced between 2006 and 2008**, specifically tailored to the **R320 (3.2L V6) variant**. This high-performance steering rack is a critical element of the vehicle s handling system, ensuring smooth, responsive, and accurate directional control while maintaining the luxury and refinement synonymous with Mercedes-Benz engineering. Crafted from durable, high-grade materials, this rack features a robust **titanium-reinforced ball joint system**, which enhances durability and reduces wear over extended use, even under demanding driving conditions. The design incorporates a **serpentine gear mechanism** that minimizes play and backlash, delivering a near-instantaneous steering response essential for both urban maneuverability and highway stability. The rack s **hydraulic assist integration** (where applicable) further optimizes effortless steering, reducing driver fatigue during long journeys. Built to exacting OEM specifications, this part is compatible with the **R-Class s front-wheel-drive architecture**, ensuring seamless fitment with the vehicle s suspension and steering linkage components. Whether replacing a worn-out original unit or upgrading for enhanced performance, this steering rack maintains the R-Class s reputation for **premium craftsmanship and reliability**, making it an indispensable component for owners seeking to preserve or restore their vehicle s original driving dynamics.

### **Pros and Cons of Buying a Mercedes-Benz Steering Gear/Rack (Part Number 551-50115) for a W221 R320 (2006-2008 R-Class)**

#### **Pros**

1. **Direct Fit and Compatibility** The part number **551-50115** is a direct replacement for the steering rack in the **W221 R320 (2006-2008)** R-Class, ensuring proper alignment and functionality without modifications.

2. **Improved Steering Feel and Precision** A new or high-quality aftermarket steering rack can enhance steering response, reduce play, and provide a more engaging drive, especially beneficial in the R-Class, which often suffers from worn-out factory racks.

3. **Reduced Noise and Vibration** Worn steering racks can produce clunking, rattling, or whining noises, particularly over rough roads. Replacing it eliminates these issues, improving overall driving comfort.

4. **Prevents Further Damage** A failing steering rack can lead to misalignment, uneven tire wear, or even steering failure in extreme cases. Replacing it proactively avoids costly repairs to other components like tie rods, bushings, or suspension parts.

5. **Increased Vehicle Safety** Proper steering function is critical for control, especially in larger vehicles like the R-Class. A new rack ensures reliable steering input, reducing the risk of accidents due to mechanical failure.

6. **Potential Cost Savings** While the upfront cost of a new or OEM-quality rack is significant, it can be more economical than repairing a severely damaged rack or associated steering components.

7. **Compatibility with Upgrades** If you plan to modify the suspension or steering (e.g., adding a sway bar, adjusting camber, or installing aftermarket steering wheels), a fresh rack ensures the system works optimally with these changes.

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#### **Cons**

1. **High Cost** OEM steering racks (e.g., from Mercedes-Benz or authorized dealers) are expensive, often ranging between **$1,200 and $2,000 ** depending on sourcing. Aftermarket options may be cheaper but vary in quality.

2. **Labor-Intensive Installation** Replacing a steering rack requires removing the steering column, tie rods, and sometimes the front wheels, making it a **multi-hour job** for a professional mechanic. DIY installation is possible but challenging due to the complexity of the system.

3. **Potential for Counterfeit Parts** If purchasing from non-authorized sellers, there s a risk of receiving a **low-quality or fake part**, which could fail prematurely or not fit correctly. Always buy from reputable suppliers.

- **Tie rods** (if worn or damaged during removal)

- **Steering column bushings** (if they ve degraded over time)

- **Power steering fluid** (if the system was drained during service)

- **Alignment** (required after installation to ensure proper handling)

5. **Limited Longevity of Aftermarket Parts** While some aftermarket racks are reliable, others may not last as long as OEM parts, especially in severe driving conditions (e.g., off-roading, aggressive driving, or extreme temperatures).

6. **Potential for Oversteering or Understeering** If the rack is not properly adjusted or if the vehicle s alignment is off post-installation, it could lead to **unpredictable handling**, requiring additional tuning.

7. **Warranty Considerations** If the vehicle is still under warranty, replacing the rack with a non-OEM part may void coverage for related components. Always check with your dealership before proceeding.

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### **Ending Conclusion**

Replacing the steering rack in a **W221 R320 (2006-2008) R-Class** with the **551-50115 part number** is a **highly recommended maintenance task** if the current rack is worn, noisy, or exhibiting poor performance. The benefits **improved safety, steering feel, and longevity** far outweigh the drawbacks, provided you invest in a **high-quality part** and have it installed by a **trusted mechanic**.

However, the **high cost and labor requirements** make it a significant financial commitment. If the rack is only mildly worn, delaying replacement may be an option, but ignoring it entirely risks **more expensive repairs down the line**.

---

### **Recommendation**

1. **Verify the Condition of the Rack** Before purchasing, confirm that the rack is indeed failing (check for leaks, excessive play, or unusual noises). If it s still functional, replacement may not be urgent.

2. **Choose the Right Part**

- **OEM (Mercedes-Benz or authorized dealer)** for maximum reliability and warranty coverage.

- **High-quality aftermarket** (e.g., **Felix, Meyle, or ACDelco**) if budget is a concern, but research reviews thoroughly.

- Avoid **no-name or suspiciously cheap** parts to prevent premature failure.

3. **Budget for Additional Costs** Account for **tie rods, labor, alignment, and potential fluid changes** to avoid surprises.

4. **Get Multiple Quotes** Compare prices from **dealerships, specialty Mercedes-Benz shops, and independent mechanics** to ensure you re getting a fair deal.

5. **Consider Professional Installation** Given the complexity, **trust a certified Mercedes-Benz technician** to ensure proper alignment and function after replacement.

6. **Monitor Post-Installation** After replacement, **test drive the vehicle** to confirm the rack is functioning correctly and that there are no unusual noises or handling issues.

**Final Verdict:** If your R-Class s steering rack is failing, **replacing it is a wise investment** for safety and driving enjoyment. Just ensure you source the right part and have it installed properly. If the budget is tight, prioritize other critical maintenance tasks first.

Details:

See below for fitment information and any notes pertaining to this specific part. It is ready to ship and comes with a 90 day warranty. Donor Vehicle. Notes: CORE VALUE 95.

Year: 2007, model: R5 Stock #: H7029, Mileage: 246000. This part will only fit: MERCEDES R-CLASS 06-07 251 Type; R350, w/speed sensitive steering, R5 07 R320, R63, 08 thru 07/31/07, R550, steering. For more parts from this vehicle.

part #: r500 prices

• $180.59-$275.59

specifications steragebo:

• for models: R500, R320
• for makes: Mercedes
• for years: 2006-2008
• mpn: R500
• part type: Steering Gear Rack
• conditions options: Core Value 95
• genuine oem: Yes
• ipn: 551-50115
• make: Mercedes-benz
• year: 2007
• manufacturer warranty: 90 Day

general steragebo:

• condition: Used
• Car Truck Parts Accessories > Steering Suspension > Gearboxes, Rack Pinions

offer steragebo:

• started: April 2, 2026
• sold: 0
• options: Ship-to-home
• quantity: 1
• availability: In Stock

seller steragebo:

• city: Lansing, Michigan
• rating: 98.9%
• # reviews: 15681

payments steragebo:

• other
• credit card: Diners-club
• wallet: Apple-pay

returns steragebo:

• time: 60 Days
• paid by: Seller
• policy: Returns Accepted

shipping steragebo:

• type: Fixed
• transit: 2-6 Days
• service: UPS Ground
• class: Standard
• cost: $0.00
• carrier: UPS

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