2001-2005 Lexus IS300 Rear Upper Control Arm: Diagnosing Clunks and Tire Wear
This guide covers common failure symptoms, replacement costs, and what to inspect when buying a used rear upper control arm for your 2001-2005 Lexus IS300.
- The most common symptom of failure is a clunking noise from the rear suspension when going over bumps.
- When buying a used arm, prioritize inspecting the ball joint for looseness and ensuring its rubber boot is not torn.
- The driver (LH) and passenger (RH) side arms are different parts and are not interchangeable.
- A four-wheel alignment is mandatory after replacing this part to prevent tire damage and ensure safe handling.
Symptoms of a Failing Rear Upper Control Arm
When the rear upper control arm on a 2001-2005 Lexus IS300 begins to fail, it's usually due to a worn-out ball joint or deteriorated rubber bushings. The symptoms can range from annoying noises to serious handling problems.
- Clunking or Knocking Noises: This is the most common symptom. You may hear a distinct clunk or knock from the rear of the car, especially when driving over bumps, potholes, or uneven pavement. This sound is often caused by excessive play in the worn ball joint or bushings.
- Squeaking or Creaking Sounds: A dry, worn-out ball joint or cracked rubber bushings can produce a squeaking or groaning noise as the suspension moves up and down. Some owners report this noise is more noticeable in wet or cold weather.
- Uneven Tire Wear: A failing control arm can no longer hold the wheel at the correct angle, leading to improper alignment. This often results in accelerated wear on the inner or outer edge of the rear tires.
- Poor Handling or Wandering: You might feel like the rear of the car is unstable, loose, or wanders, especially during cornering. This indicates that the worn components are allowing unwanted movement in the wheel assembly, making the car less predictable.
Buying a Used Rear Upper Control Arm: What to Check
For many owners, a quality used OEM control arm is a smart choice, offering original factory quality at a significant discount. However, it's crucial to inspect the part carefully before purchasing.
Pro Tip: The original Lexus/Toyota arms are made from high-quality forged aluminum or stamped steel, designed for longevity. These are often superior in material and build quality to cheap, new aftermarket alternatives which may use lower-grade materials and less durable bushings.
- Inspect the Ball Joint: This is the most critical check. The rubber boot around the ball joint should be intact, with no rips, tears, or signs of leaking grease. Grab the ball joint stud and try to move it around in its socket. It should be stiff and smooth. If it's loose, floppy, or makes noise, the joint is worn out and the arm should be rejected.
- Examine the Bushings: Check the two rubber bushings where the arm mounts to the subframe. Look for significant cracks, dry rot, or tearing. The rubber should be firm, not crumbling or separating from the metal sleeve. Minor surface cracking can be acceptable on a used part, but deep splits are a red flag.
- Check for Physical Damage: Inspect the body of the control arm for any signs of bending, heavy corrosion, or cracks, which could indicate it came from a vehicle involved in an accident.
- Verify Part Numbers: The IS300 uses different parts for the driver and passenger sides. Ensure you are buying the correct one. The passenger side (RH) is 48770-53010 and the driver side (LH) is 48790-53010.
Known Issues, Recalls, and TSBs
There are no specific recalls or widespread Technical Service Bulletins (TSBs) from Lexus for rear upper control arm failure on the 2001-2005 IS300. The failures are typically due to age, mileage, and wear.
One known challenge during replacement is access to the two inner bolts that secure the arm to the subframe. The space is very tight. On the driver's side (LH), the plastic fuel filler neck cover may need to be unbolted and moved aside to gain adequate clearance.
Compatibility Note: This part is for the 2001-2005 Lexus IS300 sold in North America. While the part may also fit the 1998-2005 Toyota Altezza (the Japanese market version), always confirm fitment for your specific vehicle.
Replacement Overview and Difficulty
- Difficulty Rating: 3 out of 5 (Moderate)
- Estimated Time: 1.5 - 2.5 hours per side for a DIY mechanic.
- DIY Feasible: Yes, for those with mechanical experience and the right tools.
The replacement process is straightforward but requires some specific tools. Removing the coilover and sway bar end link can provide much better access.
Key Tools:
- Socket set (17mm and 19mm are common sizes for this job)
- Wrenches for tight spaces
- Torque wrench
- A ball joint separator tool (highly recommended to avoid damaging the knuckle)
Pro Tip: Do not fully tighten the two inner bushing bolts until the vehicle's suspension is loaded (i.e., the car is back on the ground or the knuckle is supported by a jack to simulate ride height). Tightening these bolts while the suspension is hanging at full droop will twist the rubber bushings and cause them to fail prematurely.
An alignment is required after replacing one or both rear upper control arms to ensure proper handling and prevent tire wear.
Cost Comparison
Prices can vary based on location and supplier. The following is an estimated breakdown:
| Part Type | Estimated Cost |
|---|---|
| New OEM | $200 - $370 per arm |
| New Aftermarket | $70 - $200 per arm |
| Used OEM | $40 - $80 per arm |
| Shop Labor | $150 - $300 per side |
Frequently Asked Questions (FAQ)
Can I drive with a bad rear upper control arm?
It is not recommended. While the car may be drivable for short distances, a severely worn control arm can cause unpredictable handling, especially at high speeds or during emergency maneuvers. It will also cause rapid and uneven tire wear, costing you more money in the long run.
Should I replace rear upper control arms in pairs?
It is highly recommended. Suspension components on both sides of the vehicle experience similar wear. If one side has failed, the other is likely not far behind. Replacing them in pairs ensures balanced handling and saves you from having to do the same job twice.
Do I need an alignment after replacing the rear upper control arm?
Yes, absolutely. This part is a critical piece for setting rear wheel alignment. Failure to get a professional four-wheel alignment after replacement will result in poor handling and destroy your tires.
What's the difference between the driver and passenger side arm?
The arms are mirror images of each other and are not interchangeable. The passenger side (RH) is part number 48770-53010, and the driver side (LH) is 48790-53010. Ensure you order the correct part for the side you are repairing.
Technical Specifications
OEM Part Numbers: 48770-53010 (Rear, Right/Passenger Side) 4877053010 48790-53010 (Rear, Left/Driver Side)
The OEM part includes a non-serviceable ball joint and two pre-installed rubber bushings.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Lexus IS300: