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Views: 0 Author: Site Editor Publish Time: 11-01-2025 Origin: Site
Rubber-metal composite bushings (also known as rubber-metal bonds, elastomeric bushings, or vibration isolators) serve as critical suspension and drivetrain mounting components in Mercedes-Benz commercial vehicles including the Actros (sometimes misspelled as Acteos), Mercedes 2000 series, and Unimog U 500/U 600 (occasionally written as Unitog) models. These precision-engineered components manage the dynamic interface between rigid chassis structures and moving suspension arms, control arms, torque rods, and stabilizer links.
Primary Functions: - Vibration Isolation: Absorbing road shock and drivetrain vibrations before transmission to the cab - Noise Dampening (NVH): Reducing structure-borne noise by 15-25 dB in critical frequency ranges (80-250 Hz) - Angular & Radial Deflection Management: Allowing controlled suspension articulation while maintaining alignment geometry - Load Transfer: Distributing static vehicle weight and dynamic road loads across mounting points
For fleet operators managing Mercedes-Benz Actros trucks in long-haul European routes or Unimog utility vehicles in South American off-road applications, bushing quality directly impacts driver comfort, maintenance intervals, and total cost of ownership. Premium OE-equivalent bushings can extend service life from 150,000 km (economy aftermarket) to 300,000+ km under comparable operating conditions.
The rubber-metal composite bushing operates on three synergistic mechanical principles:
1. Viscoelastic Damping:
Natural rubber (NR) and synthetic elastomers (EPDM, NBR, FKM) exhibit time-dependent stress-strain behavior. When subjected to cyclic loading, the rubber’s molecular chains dissipate mechanical energy as heat through internal friction (hysteresis). This converts vibration energy into thermal energy, preventing resonance amplification.
2. Geometric Spring Rate Control:
The bushing’s geometry—specifically the ratio of rubber thickness to bonded surface area and the presence of internal voids or chambers—determines its directional stiffness. Radial stiffness typically ranges 500-2,000 N/mm for control arm applications, while axial stiffness is designed 30-50% lower to accommodate thermal expansion and assembly tolerances.
3. Preload & Stress Distribution:
Vulcanized bonding between rubber and metal sleeves creates a mechanically locked interface. During installation at specified torque (typically 180-350 Nm for Mercedes Actros suspension mounts), the bushing enters a preloaded state that optimizes the rubber’s working strain range (15-25% shear strain) for maximum fatigue life.
Frequency Range | Isolation Efficiency | Application Impact |
10-50 Hz | 60-75% transmissibility reduction | Engine idle vibration, driveline surge |
80-150 Hz | 70-85% reduction | Tire/road noise, suspension impacts |
200-400 Hz | 50-65% reduction | High-frequency road texture |
Material Selection:
- Natural Rubber (NR): Excellent dynamic properties, −30°C to +80°C range, vulnerable to ozone/UV - EPDM (Ethylene Propylene Diene Monomer): Superior weather/ozone resistance, −40°C to +120°C, moderate oil resistance - NBR (Nitrile Rubber): High oil/fuel resistance, −30°C to +100°C, lower resilience than NR - FKM (Fluoroelastomer): Extreme chemical/temperature resistance, −20°C to +200°C, premium cost
┌─────────────────────────────────────┐
│ Outer Steel Sleeve (Cold-Drawn) │ ← Pressed into chassis bracket
├─────────────────────────────────────┤
│ Bonded Rubber Layer (5-15mm wall) │ ← Vulcanized adhesive interface
│ [Compound: NR/EPDM blend] │
│ Internal Voids (optional) │ ← Tuned compliance chambers
├─────────────────────────────────────┤
│ Inner Steel Sleeve (Case-Hardened)│ ← Receives control arm bolt
└─────────────────────────────────────┘
1. Metal Preparation: Sleeves are degreased, grit-blasted (Sa 2.5 standard), and primed with chlorinated rubber or phenolic adhesive
2. Rubber Compounding: Mastication of base polymer + sulfur (vulcanizing agent) + carbon black (reinforcement) + antioxidants + processing oils
3. Molding: Metal sleeves positioned in compression mold, uncured rubber injected, heated to 160-180°C under 100-150 bar pressure
4. Vulcanization: Cross-linking reaction creates C-S-C bonds, transforming plastic rubber into elastic thermoset (15-30 min cure cycle)
5. Post-Cure: Oven aging at 80°C for 4-24 hours to complete cross-linking and stress relief
Material | Shore A Hardness | Temp Range | Oil Resistance | Ozone Resistance | Cost Index | Typical Application |
Natural Rubber (NR) | 50-70 | −30 to +80°C | Poor | Poor | 1.0x | Standard duty, dry environments |
EPDM | 55-75 | −40 to +120°C | Moderate | Excellent | 1.3x | All-weather, exposed installations |
NBR (Nitrile) | 60-80 | −30 to +100°C | Excellent | Moderate | 1.5x | Engine mounts, fuel system proximity |
NR/SBR Blend | 55-70 | −30 to +85°C | Moderate | Good | 1.1x | OE Mercedes standard (9603231285) |
FKM (Viton) | 70-90 | −20 to +200°C | Excellent | Excellent | 3.5-4.0x | Extreme duty, chemical exposure |
Hardness Impact:
- 50-60 ShA: Maximum isolation, softer ride, 20-30% shorter life in heavy-duty applications - 65-75 ShA: OE Mercedes specification—balanced NVH and durability for 250,000+ km - 80-90 ShA: Performance/heavy-haul upgrades, firmer handling, reduced deflection under load
OE Number | Alternate Formats | Primary Application | Dimensional Variant |
9603231285 | 960 323 12 85960-323-12-85A9603231285 | Actros MP2/MP3 front lower control arm (outboard) | Ø45mm outer × Ø20mm inner × 68mm length |
9603233835 | 960 323 38 35960-323-38-35A9603233835 | Actros MP2/MP3 stabilizer linkUnimog U 500 front axle | Ø38mm outer × Ø16mm inner × 52mm length |
9603234385 | 960 323 43 85960-323-43-85A9603234385 | Mercedes 2000 series torque rodUnimog U 600 rear mount | Ø50mm outer × Ø22mm inner × 75mm length |
9603231285 (Control Arm Bushing):
- Location: Front axle lower control arm, outer pivot point (chassis-side bracket) - Load Type: Radial compression + axial rotation (±15°) - Replacement Trigger: Clunking over bumps, steering wander, uneven tire wear - Torque Spec: 280 Nm ±20 Nm, retorque after 1,000 km
9603233835 (Stabilizer Link Bushing):
- Location: Anti-roll bar end link connection to control arm or axle housing - Load Type: Primarily axial compression with minimal rotation - Replacement Trigger: Rattling on rough roads, body roll increase - Torque Spec: 180 Nm ±15 Nm, no retorque required with nylon lock nut
9603234385 (Torque Rod Bushing):
- Location: Rear axle torque rod (radius arm) connection to chassis frame - Load Type: Longitudinal thrust (braking/acceleration) + vertical deflection - Replacement Trigger: Driveline shudder, wheel hop under braking - Torque Spec: 320 Nm ±25 Nm, retorque after 500 km and 5,000 km
Part Number | Outer Ø (mm) | Outer Ø (inch) | Inner Ø (mm) | Inner Ø (inch) | Overall Length (mm) | Overall Length (inch) | Rubber Wall (mm) |
9603231285 | 45.0 ±0.2 | 1.772 ±0.008 | 20.0 ±0.1 | 0.787 ±0.004 | 68.0 ±0.5 | 2.677 ±0.020 | 12.5 |
9603233835 | 38.0 ±0.2 | 1.496 ±0.008 | 16.0 ±0.1 | 0.630 ±0.004 | 52.0 ±0.5 | 2.047 ±0.020 | 11.0 |
9603234385 | 50.0 ±0.2 | 1.969 ±0.008 | 22.0 ±0.1 | 0.866 ±0.004 | 75.0 ±0.5 | 2.953 ±0.020 | 14.0 |
Parameter | Test Method | 9603231285 Spec | 9603233835 Spec | 9603234385 Spec |
Radial Stiffness | ISO 2694 @ 23°C | 1,450 ±150 N/mm | 980 ±100 N/mm | 1,750 ±180 N/mm |
Torsional Stiffness | DIN 53513 | 85 ±10 Nm/° | 45 ±8 Nm/° | 110 ±12 Nm/° |
Static Load Capacity | Mercedes DBL 5451 | 18 kN | 12 kN | 24 kN |
Dynamic Cycle Life | 10 Hz, ±5mm, 23°C | >5 million cycles | >3 million cycles | >4 million cycles |
Temperature Shock | −40°C / +100°C, 10 cycles | No cracking | No cracking | No cracking |
Bond Strength | 180° peel test | >25 N/mm | >22 N/mm | >28 N/mm |
Step 1: Assess Operating Temperature Range - Consistent operation −20 to +70°C → Standard NR/SBR blend (65-70 ShA) - Frequent temperature extremes −30 to +90°C → EPDM upgrade (70-75 ShA) - Proximity to exhaust, turbo, or DPF systems → NBR or FKM (75-85 ShA)
Step 2: Evaluate Chemical Exposure - Minimal fluid contact (sealed suspension) → Standard NR acceptable - Occasional fuel/oil splash → NBR minimum requirement - Hydraulic system components or marine/industrial equipment → FKM mandatory
Step 3: Determine Load Profile - Urban delivery (frequent stops, light loads) → Standard hardness (65-70 ShA) - Regional haul (moderate highway speeds, mixed loads) → OE specification (70 ShA) - Heavy haul or off-road (sustained GVW, rough terrain) → Upgraded hardness (75-80 ShA)
Vehicle Model | Operating Environment | Recommended Specification | Rationale |
Actros MP3 Long-Haul | European highways, 80% highway / 20% urban | OE 9603231285 (70 ShA NR/SBR) | Optimal NVH for driver comfort at sustained speeds |
Actros Construction | Job site access roads, frequent off-pavement | 9603231285 HD (75 ShA EPDM) | Resists UV/ozone, handles impact loading |
Unimog U 500 Municipal | Urban snow removal, salt exposure | 9603233835 HD (72 ShA EPDM) | Enhanced salt/chemical resistance, cold flexibility |
Unimog U 600 Forestry | Unpaved trails, hydraulic equipment | 9603234385 XHD (78 ShA NBR) | Oil resistance, extreme deflection tolerance |
Verify Compatibility: 1. Cross-reference part number against vehicle VIN using Mercedes WIS/ASRA system or ETK parts catalog 2. Measure old bushing dimensions if using aftermarket replacement—counterfeit parts may deviate ±1-2mm 3. Inspect mating surfaces on control arm and chassis bracket for corrosion, distortion, or cracks
Step 1: Remove Old Bushing - Support vehicle on jack stands at chassis jacking points (NOT suspension arms) - Remove mounting bolt and lower suspension to relieve preload - Use bushing removal tool to press out old bushing—apply force parallel to bushing axis - Common Error: Attempting removal with suspension loaded causes tool damage and deformed control arm
Step 2: Install New Bushing - Apply thin film of dish soap solution to outer sleeve (NOT petroleum-based lube which degrades rubber) - Align bushing with bore, ensure any orientation markings face correctly - Press bushing until outer sleeve is flush ±0.5mm with bracket face - Critical: Press force should not exceed 30 kN—higher force indicates misalignment
Step 3: Bolt Installation & Torquing - Insert new bolt through inner sleeve, hand-tighten nut - IMPORTANT: Raise suspension to ride height (wheels touching ground) BEFORE final torquing - Torque to specification in three stages: - Stage 1: 30% of final torque (e.g., 85 Nm for 280 Nm spec) - Stage 2: 80% of final torque (225 Nm) - Stage 3: Final torque (280 Nm) ±3% using calibrated torque wrench
Part Number | Application Location | Initial Torque | Retorque Interval 1 | Retorque Interval 2 |
9603231285 | Front control arm (outboard) | 280 Nm ±20 Nm | 1,000 km / 2 weeks | 10,000 km / 3 months |
9603233835 | Stabilizer link | 180 Nm ±15 Nm | Not required | Not required |
9603234385 | Torque rod mount | 320 Nm ±25 Nm | 500 km / 1 week | 5,000 km / 6 weeks |
Retorque Rationale:
Vulcanized rubber exhibits stress relaxation—molecular chains redistribute under sustained load, reducing clamping force by 10-15% in first 1,000 km. Retorquing restores optimal preload and extends bushing life by 20-30%.
Error | Consequence | Prevention |
Torquing with suspension unloaded | Preloads rubber in twisted state, causes premature tearing | Always torque at ride height with wheels supporting vehicle weight |
Using petroleum-based lubricant | Rubber swelling and softening, 40-60% life reduction | Use water-based soap solution or specified silicone spray only |
Reusing stretch bolts | Insufficient clamping force, bushing rotation in bore | Replace bolts if stretch measured or per Mercedes service interval |
Pressing bushing beyond flush | Compresses rubber excessively, distorts inner sleeve | Press until outer sleeve is flush ±0.5mm, use depth gauge to verify |
Symptom | Visual Indicator | Root Cause | Corrective Action |
Clunking/knocking over bumps | Rubber torn or separated from sleeve | Improper installation torque, suspension travel exceeded design limits | Replace bushing, verify mounting bolt condition, retorque per spec |
Steering wander at highway speed | Excessive radial wear, oval-shaped bore | Hardness too soft for load (overloaded vehicle), contamination by oil | Upgrade to 75 ShA HD grade, inspect for fluid leaks, realign suspension |
Squeaking/creaking during turns | Surface cracking (ozone) or dry bonding zones | UV/ozone exposure on NR compound, insufficient lubrication during install | Replace with EPDM compound bushing, apply anti-seize to bolt threads only |
Rapid rubber deterioration (<50k km) | Swelling, softening, discoloration | Chemical attack (diesel, hydraulic fluid, ATF exposure) | Upgrade to NBR or FKM, repair fluid leak source, clean installation area |
Uneven tire wear (feathering) | Bushing appears intact but deflected | Incorrect hardness selection (too soft), exceeding angular limits | Install correct hardness grade, verify suspension not modified beyond OE specs |
Vibration at 80-120 km/h | Rubber chunking or internal delamination | Fatigue from high-frequency road texture (concrete highways) | Replace with higher-resilience compound, consider adding supplemental dampers |
Hebei Huami New Material Technology Co., Ltd. is a specialized manufacturer of rubber-metal composite components with comprehensive capabilities:
• Established: 1998 (26+ years of commercial vehicle component expertise)
• Location: Xingtai City, Hebei Province, China—specialized rubber-plastic industrial zone
• Production Capacity: Annual output value 416 million RMB (2024), with 600+ employees including 100+ R&D engineers
• Stock Exchange: Beijing Stock Exchange listed company (Stock Code: 836247, listed December 2022)
• Patents & Standards: 47 authorized patents (19 invention patents, 28 utility model patents); participated in drafting 9 national standards, 1 industry standard, 4 group standards
• ✓ IATF 16949:2016 – Automotive quality management (certified since 2006)
• ✓ ISO 9001:2015 – General quality management
• ✓ ISO 14001:2015 – Environmental management
• ✓ ISO 45001:2018 – Occupational health & safety
• ✓ GJB 9001C – Chinese military quality standard
• ✓ AS9100D – Aerospace quality management
• ✓ AEO Certification – Chinese customs advanced certification (December 2024)
Final Validation Testing: - Dynamic Fatigue Testing: Random sampling (1 per 500 pcs) subjected to 10 Hz radial loading, ±5mm displacement, 23°C ambient until failure or 5 million cycles—failure rate target <0.1% - Bond Strength Testing: 180° peel test on witness samples from each production batch, minimum 25 N/mm average - Environmental Testing: Thermal shock cycles (−40°C 4h / +100°C 4h × 10 cycles) on batch samples - Dimensional Verification: CMM scanning of critical dimensions on first/middle/last piece of each production run
• Laser-etched date codes on steel sleeves (format: YY/WW/LOT)
• QR codes linking to production batch records
• Certificate of Conformance (C of C) provided with each shipment
• RoHS 2.0 / REACH compliance—all materials tested for restricted substances
Available Options: - Hardness Variants: 60-65 ShA (Comfort), 75-78 ShA (Heavy-Duty), 80-85 ShA (Extreme-Duty) - Material Upgrades: EPDM all-weather, NBR oil-resistant, FKM extreme-temperature - Dimensional Modifications: Non-standard bore diameters, length adjustments, reinforced wall thickness
Minimum Order Quantities: - Standard OE equivalent parts: 100 pieces per SKU - Custom hardness variations: 200 pieces per specification - Non-standard dimensions: 500 pieces minimum
Lead Times: - Standard catalog items: 15-20 days after order confirmation - Custom hardness/material: 25-30 days - New dimension tooling: 45-60 days
Cross-reference your vehicle VIN using Mercedes-Benz WIS (Workshop Information System) or ETK (Electronic Parts Catalog). The part number format may appear as 9603231285, 960 323 12 85, or A9603231285—these are identical parts with different formatting conventions.
Shore A hardness directly impacts stiffness and durability. A 65 ShA bushing (OE specification) provides optimal NVH isolation for standard GVW operations with expected 250,000+ km life. A 75 ShA bushing increases radial stiffness by approximately 15%, reducing deflection under heavy loads.
Rubber exhibits stress relaxation—molecular chains redistribute under sustained load, reducing bolt clamping force by 10-15% in the first 1,000 km. Retorquing restores optimal preload and extends bushing life by 20-30%.
For custom hardness variants using standard dimensions, MOQ is 200 pieces per specification with a 25-30 day lead time. For completely non-standard dimensions requiring new mold tooling, MOQ increases to 500 pieces with 45-60 days lead time.
Yes. Our manufacturing processes comply with IATF 16949:2016 automotive quality standards, and our products meet RoHS 2.0 and REACH regulations for European market compliance. We can provide material certifications, dimensional reports, and fatigue test data to support your TÜV application process.
