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Views: 0 Author: Site Editor Publish Time: 10-27-2025 Origin: Site
A torque rod rubber bushing (also called torque/thrust rod bushing) is the rotating elastic pivot between the rear axle and frame torque rods on heavy trucks. Between the inner/outer steel sleeves, the rubber layer works in shear and compression to:
• NVH control: filter axle/frame high-frequency vibration and impact, cut cab boom/harshness.
• Axle location: provide tuned non-linear stiffness in longitudinal/lateral/torsional axes, keeping wheelbase & caster geometry from drifting.
• Durability: work via elastomer strain instead of metal-to-metal friction, reducing wear and lubrication needs in mud/water/salt.
Design notes: Rubber thickness, compound, and hardness define shear angle, stiffness curve, and fatigue life. Chemical bonding of rubber to sleeves governs de-bond resistance.
Typical construction
• Outer sleeve: carbon/alloy steel, press-fit into bracket; e-coat/anti-rust on OD.
• Rubber layer: carries shear/compression, sets NVH & durability.
• Inner sleeve: clamps with the bolt; transmits clamp load and rotation.
• Bonding system: surface prep + primer/topcoat (e.g., Chemlok®) + curing to form chemical adhesion that resists hot water, salt spray, and oil.
Elastomers & hardness (recommended ranges)
Material | Shore A | Temperature (°C) | Medium/Weathering | Notes & Use |
NBR (Nitrile) | 70–85 | −30 ~ 110 | Excellent oil/fuel resistance | Preferred for leakage-prone axle/diff areas |
EPDM | 65–80 | −40 ~ 120 | Ozone/steam/salt resistant | Cold/wet/snow-salt regions |
CR (Neoprene) | 70–80 | −30 ~ 100 | Balanced flame/weathering | Good bonding & stable dynamics |
NR/BR blend | 70–85 | −35 ~ 90 | Low hysteresis | Better high-frequency comfort |
Fitment & common interchange numbers
• Primary OE: AZ9725529213 (widely used on SINOTRUK/HOWO torque rods). The size 90×57×130 mm with 25 mm bore is commonly listed for this OE reference (verify on your assembly).
• Market variants: WG9725529213; occasionally AZ9725520291 appears in listings/related tags; always verify geometry and hardness before swapping.
• Typical platforms in listings: HOWO/Howo A7, some Shacman F2000/F3000 depending on bracket/axle—verify at assembly level.
Quick dimension & tolerance reference (typical)
Parameter | Typical (mm) | Inch | Tolerance / fit (ref.) |
OD | 90.0 | 3.54" | ±0.30 mm |
Rubber width W | 57.0 | 2.24" | ±0.30 mm |
Overall length L | 130.0 | 5.12" | ±0.50 mm |
Bore ID | 25.0 | 0.98" | H7 (+0 / +0.021 mm) |
Sleeve coaxiality | — | — | ≤ 0.05 mm |
Sleeve bore roughness | — | — | Ra ≤ 1.6 μm |
• Load: GVW, axle static load, sprung/unsprung mass.
• Road: Highway 70–75A; Mixed duty 75–80A; Quarry/washboard/off-road 80–85A.
• Temperature: Cold climate (≤ −30 °C) → EPDM or low-Tg NR/BR; High temp (> 90 °C) → NBR/FKM (if oils present).
• Oil exposure: Diff/seal seepage or diesel wash → NBR 70–80A with oil-aging-resistant bonding.
• NVH target: For comfort-first, consider −5A hardness and/or cavity/rib structures while safeguarding displacement capacity.
Installation (with bracket/rod removed)
• Clean & inspect: remove corrosion/burrs in the bracket bore; keep new bushing free of mineral oil.
• Press-fit: use a coaxial press tool; no hammering. Use light soap-water if needed (avoid oil/grease).
• Orientation: align inner sleeve marks to bracket index (some models have angle indexing).
• On-vehicle assembly: torque link bolts at normal ride height to avoid pre-twist in the rubber.
• Anti-loose: use correct locknuts/torque-to-yield bolts or threadlocker per OEM.
Reference torques (class 10.9, dry — follow the vehicle manual)
Bolt | Torque (Nm) |
M16 | 180–220 |
M18 | 260–300 |
M20 | 350–430 |
M24 | 550–650 |
Retightening: 500–1,000 km initial check; then every 20,000–30,000 km or 6 months.
Common mistakes
• Torquing at full droop → permanent pre-twist and early cracking.
• Using mineral oil during press-fit → bond contamination.
• Poor coaxiality/angled pressing → edge wear & noise.
Symptom | Likely Cause | Remedy |
Tip-in clunk/brake shudder | Rubber shear fatigue, cracking or de-bond | Replace bushing; check torque & alignment |
Saw-tooth tire wear | Geometry drift; rubber too soft | +5A hardness; re-verify axle alignment |
Straight-line pull | Sleeve misalignment; wrong mounting angle | Reinstall & torque at ride height; correct concentricity |
Rubber swelling & softening | Long-term oil/diesel exposure | Switch to NBR; fix leaks |
Winter cracking | Low-temp brittle compound | EPDM/low-Tg blends; update compound |
Adhesion failure | Contaminated surfaces or aged primer | Upgrade primer/topcoat; tighten cleaning & cure profile |
• Systems & traceability: IATF 16949, TÜV; batch laser code + compound/bond batch traceable; dynamic-stiffness curves archived.
• Typical tests: hardness/CS/rebound; dynamic stiffness–frequency; peel ≥ 10–12 N/mm; salt-spray 240–480 h (metal parts); oil/ozone/low-temp impact; fatigue ≥ 10^6 cycles.
• Process control: shot-blast grade, primer thickness, cure temperature–time curve, cooling/aging, post-treat.
• Case: A HOWO fleet (quarry + washboard) moved from 75A to 80A NBR and upgraded bonding—service interval extended ~30–40% and noise complaints dropped.
Q: Is AZ9725529213 interchangeable with WG9725529213?
A: Geometry is often similar, but hardness & bonding can differ. Verify dimensions + hardness before replacement.
Q: What are common dimensions?
A: Frequently listed: OD 90 mm × width 57 mm × length 130 mm, ID 25 mm; confirm against your bracket/rod assembly.
Q: How to improve life in oily axle areas?
A: Use NBR 75–80A, fix leaks, consider splash shields.
Q: Must I torque the links at ride height?
A: Yes. Torquing at droop pre-twists the rubber and shortens life.
Q: Can I reduce cab resonance/clunk?
A: Try −5A hardness or cavity/ribbed structures with adequate travel.
Q: What’s the first retorque interval?
A: After 500–1,000 km, then every 20–30k km or 6 months.
Q: Can you reverse-engineer from an old part?
A: Yes—by drawing/OE/sample with an interchange report.
Q: Do you supply test reports & traceability?
A: Each batch includes hardness/adhesion/dynamic stiffness and trace codes; 3rd-party tests on request.
Q: Materials for extreme cold?
A: EPDM 65–75A or low-Tg NR/BR blends for flexibility and anti-crack.
Q: Warranty?
A: Standard 12 months / mileage-based by agreement; RCA support for early failures.
