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Views: 0 Author: Site Editor Publish Time: 11-07-2025 Origin: Site
The Front Lower Control Arm Bushing sits at the joint between the control arm and the subframe/body. As a rubber–metal composite, it delivers stiffness where needed and compliance where desired across multiple axes:
· Location & handling: limits control-arm DOF under steering/braking/acceleration to maintain camber/caster/toe; reduces pull and abnormal tire wear.
· Ride comfort: axial/radial compliance of the rubber layer absorbs fine vibration and road impacts.
· NVH: tuned dynamic stiffness and rubber hysteresis attenuate structure-borne noise; robust rubber-to-metal bonding prevents low-temperature squeal and knock after thermal aging.
· Inner sleeve: precision-machined or cold-drawn steel tube; phosphate/zinc anti-corrosion; clamps with the bolt to transmit torque and axial clamping force.
· Rubber layer: NR / NBR / HNBR / PU; by adjusting hardness, section geometry, and formulation we tune static/dynamic stiffness, rebound, and media resistance.
· Outer sleeve: roll-formed steel shell; blasted + primed to ensure OD retention and concentricity during press-fit.
· Vulcanized bond (rubber-to-metal): single-cure primer/adhesive/topcoat tri-layer; peel strength meets/exceeds ASTM D429; resists oil, hot-water shock, and thermal cycling.
Material | Typical Hardness (Shore A) | Continuous Temp | Oil/Fuel Resistance | NVH Behavior | Typical Use |
NR (Natural Rubber) | 55–70 | −40 to +90 °C | ★ | Compliant, very quiet | Comfort, urban roads |
NBR (Nitrile) | 60–75 | −30 to +110 °C | ★★★ | Slightly firmer | Light/medium oil exposure |
HNBR (Hydrogenated NBR) | 60–80 | −40 to +150 °C | ★★★★ | Stable vs. heat/oil | High temp + oil contamination |
PU (Polyurethane) | 70–85 | −40 to +120 °C | ★★ | High stiffness | Sport/heavy-duty/unpaved |
Tip: Daily comfort → 60–65A NR/HNBR. Heavy load/rough roads/high temp + oil → 70–75A HNBR or PU. Thickened outer sleeve and stiffened rubber versions are available for LATAM road conditions.
Standard: 31126757624
BMW segmented: 31 12 6 757 624
Common variants/mistypes: 3112 6757624 (spaces); 31-12-6-757-624 (hyphenated); 3112675762 (one digit missing); 31126757624A/B (suffix—verify dimensions).
Fitment: BMW 3-Series sedan (various platforms/years). Typical location: front lower control arm bushing (“lollipop”). Always verify by VIN and service manual/measurement; platform updates can change OD/width/eccentric design.
Variant | Outer Ø OD | Inner Ø ID | Overall Width W | Flange T | Ref. Tolerance |
A | 60.0 mm (2.362 in) | 14.2 mm (0.559 in) | 49.5–50.0 mm (1.949–1.969 in) | 3.0 mm (0.118 in) | OD/ID ±0.20 mm; W/T ±0.15 mm |
B | 62.0 mm (2.441 in) | 14.2 mm (0.559 in) | 49.5–50.0 mm (1.949–1.969 in) | 3.0 mm (0.118 in) | Same as above |
C | 66.0 mm (2.598 in) | 14.2 mm (0.559 in) | 49.5–50.0 mm (1.949–1.969 in) | 3.0 mm (0.118 in) | Same as above |
Interference-fit micro-tuning: If press-fit is too loose/tight, we can supply +0.05 / +0.10 mm OD micro-oversize versions; or share your subframe bore tolerance bands for reverse matching.
1. Confirm position & OD variant: remove the old part or measure the subframe bore; compare with the table above.
2. Road condition: Urban/highway → 60–65A (comfort & quiet); Unpaved/rough >30% → 70–75A (PU optional).
3. Load: Frequent full load/towing/aggressive accel/braking → +5A hardness and consider a thickened outer sleeve.
4. Temperature: Hot zones/near engine bay → HNBR preferred.
5. Oil contamination: Seepage/fuel contact → NBR/HNBR.
6. NVH target: Quiet-cabin priority → NR 60–62A with dynamic stiffness tolerance ≤ ±10%.
7. Supply: Sample MOQ 50–100 sets; typical 7–15 days; customization 20–30 days (excluding new tooling).
CTA: Need oil/high-temp formulation, +5A hardness, or OD micro-oversize? Share your duty cycle & dimensions (see Contact & CTA).
Tools: Hydraulic press + dedicated press cups/guide sleeves; torque wrench; marker; cleaner; oil-resistant assembly lube (apply on metal interfaces only—never on the rubber/bondline).
8. Lift the vehicle, remove the wheel, support the lower arm; mark the static ride-height position on the arm.
9. Remove fixing bolts and the ball joint; take out the old bushing assembly; clean and inspect the bore.
10. Orientation & alignment: follow index notch/arrow/shoulder on the shell and press square to avoid eccentricity.
11. Press the new bushing to the shoulder stop, ensuring coaxiality and full seating.
12. Re-assemble the arm; snug bolts only. Lower to design ride height before final torque to avoid rubber pre-twist.
13. Road-test and re-inspect.
Reference torque (planning): Main bolt 120–140 N·m; Bracket→subframe 90–105 N·m. Re-torque after 800–1,200 km; recheck after severe impacts.
· Final torque with wheels hanging → long-term rubber twist & early cracking → torque at ride height.
· Lubricant on rubber → bondline slip/migration → apply lube only on metal interfaces.
· Wrong orientation or eccentric press → NVH anomalies, vehicle pull → align to index marks.
· Corroded bore untreated → loose press-fit → blast/repair first, or choose micro-oversize OD.
· Incorrect torque → clunking or thread damage → use a calibrated torque wrench and record values.
Symptom | Possible Cause | Solution |
“Thump” at start/stop | Rubber debonding or hardening | Replace; choose higher bonding-grade compound |
Vehicle pulls / abnormal tire wear | Eccentric install / loose OD fit | Re-press & align; choose +0.05 mm OD |
Cold-weather squeal | Rubber too hard / poor low-temp loss | Use NR 60–62A or low-temp-optimized HNBR |
Brake shudder | Dynamic stiffness deviation | Choose NVH-tuned version (dynamic stiffness ≤ ±10%) |
Early cracking/swelling | High temp + oil/chemical attack | Choose NBR/HNBR; locate & fix oil leaks |
Press-fit scarring / shell deformation | Misaligned tooling / uneven load | Use dedicated press cups + guides; press evenly |
· IATF 16949 process management; TÜV; AEO Advanced (2025-01-09). PPAP/IMDS available on request.
· Lab: ASTM D2240 hardness, ISO 37 tensile, ISO 815 compression set, ASTM D429 rubber-to-metal peel, ozone/heat aging, salt spray, NVH dynamic-stiffness bench.
· Traceability: unique piece barcode + batch ID; full trace of compound/formulation and key operations.
· Differentiators: OD micro-tuning (+0.05/+0.10 mm), hardness customization (60–85A), thickened outer sleeve, oil/high-temp formulations; optional CMM report and peel/hardness data with shipment.
· Case snapshots: EU shop using 65A NR comfort version → lower low-speed noise claims; LATAM distributor using 70–75A HNBR reinforced → notable durability gains (client-authorized aggregated data).
· Supply: Sample MOQ 50–100 sets; typical 7–15 days; customization 20–30 days.
· Q: Is 31126757624 the same as 31 12 6 757 624?
A: Yes; BMW’s segmented format. Also seen as 31-12-6-757-624. Verify size & position.
· Q: Comfort vs. handling?
A: Urban/highway → 60–65A; aggressive driving/rough roads → 70–75A or PU.
· Q: Cold-weather squeal?
A: Use NR 60–62A or low-temp HNBR; verify alignment.
· Q: Long-term oil contamination?
A: Select NBR/HNBR and fix leak source.
· Q: Micro-oversize OD available?
A: Yes—+0.05 / +0.10 mm and tailored tolerance bands.
· Q: Wheel alignment after replacement?
A: Recommended to restore geometry and tire wear.
· Q: NVH-tuned versions?
A: Yes—dynamic stiffness tolerance within ±10%.
· Q: Lead time & MOQ?
A: Samples 50–100 sets; 7–15 days typical; 20–30 days customization.
· Q: PPAP & test reports?
A: Yes—PPAP/IMDS, CMM dimensions, peel/hardness, dynamic-stiffness data.
