2000-2009 Honda S2000 Rear Lower Control Arm: Solving Clunks and Seized Bolts

Symptoms of a Failing Rear Lower Control Arm

Failure of the rear lower control arm is almost always due to worn-out rubber bushings, not the metal arm itself. When these bushings degrade, they allow excessive movement, leading to a series of noticeable symptoms.

1. Clunking or Popping Noises

The most common sign of a bad rear lower control arm is a distinct clunking, popping, or knocking sound coming from the rear of the car. This noise is most apparent when driving over bumps, potholes, or uneven road surfaces. You may also hear it during cornering or when the suspension articulates, such as when entering a steep driveway. The sound is caused by the metal inner sleeve of a worn bushing knocking against the control arm or the subframe.

2. Unstable Handling and Steering Wander

Worn bushings can create a feeling of instability or looseness in the rear of the car. You might notice the car wandering or pulling to one side, requiring constant steering corrections to keep it tracking straight. In some cases, you may experience a 'wobbly' or 'shimmy' feeling from the rear over bumps. This happens because the worn bushings can no longer hold the wheel securely in its correct alignment.

3. Uneven and Premature Tire Wear

A healthy control arm is essential for maintaining proper wheel alignment. When the bushings fail, the alignment settings—particularly camber and toe—can shift unpredictably. This leads to accelerated and uneven tire wear. A visual inspection of your rear tires might reveal excessive wear on the inside or outside shoulder, a clear sign that the suspension is not holding its geometry.

The #1 Problem: Seized Alignment Bolts

The single biggest challenge related to the S2000's rear lower control arms is seized alignment bolts. This issue is extremely common, especially in regions that use road salt.

Why It Happens

The problem stems from a simple case of galvanic corrosion. The factory-installed bolts are made of steel, while the subframe they pass through is aluminum. Over time, moisture and salt create an electrochemical reaction that effectively welds the bolt to the bushing's inner sleeve. Since the bolts were not greased from the factory, this is a near-inevitable failure on cars exposed to the elements.

Diagnosis and Repair

An alignment technician will be the first to discover this problem when they are unable to turn the cam bolts to adjust camber and toe. For a DIY mechanic, attempting to loosen the bolt with a breaker bar will often result in either no movement or snapping the head off the bolt.

The standard solution is to cut the bolt out on both sides of the bushing using a reciprocating saw (Sawzall) or an angle grinder. This destroys the bolt and allows the control arm to be removed. You must have new OEM alignment bolts and nuts ready for reinstallation.

Buying a Used Rear Lower Control Arm

Given the high cost of new OEM control arms, a used OEM part is an excellent and popular choice for the S2000. The metal arm itself is very durable; the only concern is the condition of the integrated bushings.

What to Inspect

• Bushings are Key: There are three bushings on the arm. Carefully inspect the rubber of all three. Look for any signs of cracking, tearing, splitting, or deterioration. The rubber should be firm and intact.
• Check for Bends and Cracks: While rare, damage from an accident or major pothole impact can bend or crack the arm. Lay it on a flat surface to check for any warping.
• Surface Corrosion: Surface rust on the cast iron arm is normal and purely cosmetic. It does not affect the structural integrity of the part. Do not worry about surface rust unless it is deep and flaking, indicating extreme neglect.

Why Used OEM is Often Better Than New Aftermarket

For a precision-handling car like the S2000, maintaining the exact factory suspension geometry is crucial. A genuine used Honda arm is guaranteed to have the correct dimensions. Many cheap, new aftermarket arms may use lower-quality rubber for the bushings, which can wear out quickly or provide a mushy, unresponsive feel. Unless you are upgrading to a known performance brand like Hardrace, a good-condition used OEM arm is a safer and often more reliable choice.

Cost of Replacement

The cost to replace a rear lower control arm can vary significantly based on whether the alignment bolts are seized.

Replacement Overview & Special Procedures

Replacing the rear lower control arm is a job of moderate difficulty that can become very hard if bolts are seized.

Key Steps

1. Safely raise and support the vehicle on jack stands and remove the rear wheel.
2. Disconnect the sway bar end link from the control arm.
3. Remove the lower shock bolt that passes through the control arm.
4. Disconnect the control arm from the rear knuckle. This may involve the lower ball joint stud.
5. Attempt to loosen and remove the two large alignment bolts holding the arm to the subframe. If they are seized, they will need to be cut out with a reciprocating saw.
6. Install the new control arm. Loosely tighten the bolts.
7. Re-attach all other components.
8. CRITICAL: With the wheel back on, lower the car onto ramps or blocks so the full weight is on the suspension. Only then should you tighten the main control arm bolts to their final torque specifications. This procedure, known as 'clocking the bushings', prevents them from being under constant tension and failing prematurely.
9. Take the vehicle for a professional four-wheel alignment immediately.

Important Torque Specs

Always use a torque wrench for final assembly. These specs are for reference; verify with a service manual for your specific year.

• Lower Control Arm to Subframe Bolts (Cam Bolts): 58 ft-lbs (78 Nm)
• Shock Absorber Lower Bolt: 47 ft-lbs (64 Nm)
• Lower Ball Joint Castle Nut: 43-51 ft-lbs (59-69 Nm)

Technical Specifications & Part Numbers

OEM Part Numbers

These parts fit all 2000-2009 Honda S2000 models (AP1 & AP2).

• Right (Passenger Side) Rear Lower Control Arm: 52350-S2A-000
• Left (Driver Side) Rear Lower Control Arm: 52360-S2A-000

The arms come with new bushings pre-installed from Honda. Mounting hardware and the ball joint are not included.

Related Part Numbers (Highly Recommended)

• Rear Adjusting Bolt (Cam Bolt): 52387-S2A-000
• Rear Camber Adjusting Plate: 52388-S2A-000
• Flange Nut (14mm): 90216-S2A-000

Frequently Asked Questions (FAQ)