How to Use Eccentric Screws for Wheel Alignment

Eccentric screws (Eccentric Camber Bolts / Alignment Bolts) are crucial components in wheel alignment, primarily used for fine-tuning camber angle or toe angle. Below is a detailed guide on their usage, adjustment steps, and precautions.

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1. Purpose of Eccentric Screws

• Adjust Camber Angle: By rotating the eccentric screw, the suspension mounting point shifts, altering the tire’s tilt.

• Some Models Allow Toe Adjustment: Certain designs permit minor toe adjustments for front or rear wheels.

• Replaces Factory Bolts: OEM bolts may lack adjustability; switching to eccentric screws expands alignment flexibility.

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2. Structure of Eccentric Screws

• Eccentric Washer (Cam): The screw head or washer has an offset design, moving suspension components when rotated.

• Calibration Marks: High-end screws may include angle indicators for precision adjustments.

• High-Strength Material: Typically made of chromoly steel or heat-treated alloy for durability.

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3. Installation & Adjustment Steps

🔧 Step 1: Preparation

• Park the vehicle on a wheel alignment machine and secure the steering wheel.

• Lift the car and remove the wheel requiring adjustment (e.g., front wheel for camber adjustment).

• Locate the upper or lower control arm mounting bolt (common on MacPherson struts or double-wishbone suspensions).

🔧 Step 2: Remove OEM Bolt

• Use a torque wrench to remove the factory bolt (support the suspension to prevent sudden drops).

• Clean the bolt hole to ensure no rust or debris remains.

🔧 Step 3: Install Eccentric Screw

• Insert the eccentric screw into the original hole without tightening yet.

• Observe the washer’s initial position (usually "neutral" for minimal offset).

🔧 Step 4: Adjust Alignment

1. Connect the alignment machine to read current camber/toe data.

2. Rotate the eccentric screw:

   • Turning clockwise/counterclockwise moves the suspension mounting point.

   • Each 90° rotation changes camber by ~0.25°–0.5° (refer to vehicle specs).

3. Monitor alignment data until reaching recommended values (e.g., camber: -0.5° to +0.5°).

🔧 Step 5: Tighten the Screw

• Once adjusted, torque the screw to OEM specs (typically 80–120 Nm).

• Recheck alignment to confirm no shift occurred.

🔧 Step 6: Road Test

• Reinstall the wheel and conduct a short test drive to check for noises or pulling.

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4. Key Precautions

⚠️ Safety First:

• Support the suspension properly when removing bolts to avoid sudden drops.

• Always use a torque wrench to prevent loosening or breakage.

⚠️ Limited Adjustment Range:

• Eccentric screws allow minor corrections (±1° max). For larger deviations, use adjustable control arms or aftermarket kits.

⚠️ Compatibility Check:

• Not all vehicles support eccentric screws—verify thread specs (e.g., M12×1.25, M14×1.5).

⚠️ Post-Alignment Inspection:

• Recheck torque and alignment after 500–1,000 km of driving.

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5. FAQs

❓ Q: Can eccentric screws adjust caster angle?
→ Generally no—caster requires subframe adjustments or shims.

❓ Q: Are eccentric screws suitable for modified cars?
→ Yes, but lowered vehicles may need extended screws or adjustable arms for greater range.

❓ Q: Do eccentric screws weaken the suspension?
→ High-quality screws (e.g., SPC, Whiteline) meet strength standards, but cheap ones may fail.

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✅ Summary

1. Eccentric screws enable camber/toe micro-adjustments—confirm compatibility first.

2. Always use an alignment machine for precision.

3. Proper torque is critical to avoid safety risks.

4. For extreme adjustments, consider adjustable control arms or aftermarket solutions.

Used correctly, eccentric screws optimize tire contact, enhancing handling and tire life! 🚗💨