2017-2018 Fiat 124 Spider Rear Upper Control Arm: Diagnosing Clunks and Choosing the Right Part
This guide clarifies the common clunking noises from the rear suspension and ensures you order the correct upper control arm for your 2017-2018 Fiat 124 Spider.
- This part is the REARWARD of the two upper control arms. Verify the position before ordering.
- The identical part from a 2016+ Mazda MX-5 (N243-28-20X) is significantly cheaper than the Fiat-branded part.
- The most common failure symptom is a clunking noise from the rear over bumps.
- A wheel alignment is absolutely required after replacing this part to prevent tire damage and ensure safe handling.
Understanding the Fiat 124 Spider & Mazda MX-5 Connection
The 2017-2018 Fiat 124 Spider is built on the same chassis as the fourth-generation Mazda MX-5 Miata (often called the 'ND'). Because of this, they share the exact same suspension design and many of the same parts. This is great news for owners, as the identical Mazda-branded parts are often much less expensive than their Fiat-branded counterparts. When searching for this part, looking for a 2016-2018 Mazda MX-5 part will yield more results and better prices.
Warning: The rear suspension has FIVE separate arms (or links) per side. There are two upper arms. This guide refers to the rearward upper arm, also called the upper lateral link. The other is the forward upper arm, or guide link. Always verify the position of the failed arm on your vehicle before ordering a replacement.
Symptoms of a Failing Rear Upper Control Arm
Failure of this control arm is almost always due to worn-out rubber bushings, not the metal arm itself unless the vehicle has been in a collision. When the bushings degrade, they allow for excess movement, leading to several distinct symptoms.
- Clunking or Popping Noises: This is the most common complaint. You may hear a metallic clunk, pop, or creak from the rear of the car, especially when going over bumps, accelerating from a stop, or during hard cornering. This sound is the metal-on-metal contact within the joint as the worn bushing allows the arm to shift suddenly.
- Vague or Wandering Rear End: The car may feel unstable, especially at highway speeds or in turns. It might feel like the rear of the car is 'steering' slightly on its own. This is because the worn bushing can no longer hold the wheel at the correct angle.
- Uneven Tire Wear: A bad upper control arm can disrupt the wheel's camber angle. This often leads to excessive wear on the inside or outside edge of the rear tires.
- Visible Wheel Movement: In severe cases, you may be able to physically move the top of the wheel in and out when the car is parked.
How to Diagnose a Bad Rear Upper Control Arm
- Safely Lift the Vehicle: Park on a level surface, engage the parking brake, and chock the front wheels. Use a jack to lift the rear corner you're inspecting and secure it with a jack stand under a strong frame point. Never work under a car supported only by a jack.
- Check for Wheel Play: Grab the rear wheel at the 12 o'clock and 6 o'clock positions. Try to rock it in and out. There should be no movement or clunking sounds. Any play at this axis points to a problem with the control arm bushings or the wheel bearing.
- Visual Inspection: With a flashlight, carefully inspect the rubber bushings at both ends of the rearward upper control arm. Look for visible cracks, tearing, missing chunks of rubber, or fluid leaking from fluid-filled bushings. Compare the suspect bushing to the one on the other side of the car to spot differences.
Pro Tip: Use a small pry bar to gently apply pressure to the control arm near the bushings. If the arm moves easily relative to its mounting points on the subframe or knuckle, the bushings are worn and the arm should be replaced.
Buying a Used Rear Upper Control Arm
This is an excellent part to buy used. The control arm itself is a robust piece of stamped steel that rarely fails. The value is in the condition of the pre-installed OEM bushings. A good used OEM arm is often a better choice than a cheap, new aftermarket part with low-quality bushings.
- Inspect the Bushings: This is the most important check. The rubber should be black, pliable, and free of any cracks, tears, or signs of dry rot. Reject any arm with damaged bushings, as replacing them is difficult and not cost-effective.
- Check for Damage: Inspect the arm for any signs of bending, heavy scraping, or collision damage. While durable, a significant impact can bend the arm, which will make alignment impossible.
- Confirm the Part Number: Whenever possible, buy the Mazda version (N243-28-20X) to save money. It is identical to the Fiat part. Used examples can often be found for a fraction of the cost of a new part.
- Mileage Isn't Everything: An arm from a 50,000-mile car that lived in a hot, dry climate may have worse bushings than one from a 100,000-mile car from a mild climate. Physical inspection is more important than the donor vehicle's mileage.
Cost Comparison for Rear Upper Control Arm Replacement
| Part Type | Estimated Cost | Notes |
|---|---|---|
| New OEM (Fiat) | $250 - $366 | Part number 68313926AA. The most expensive option. |
| New OEM (Mazda) | $65 - $85 | Part number N243-28-20X. Identical part, significantly cheaper. |
| Used OEM (Mazda/Fiat) | $25 - $75 | Best value. Inspect bushings carefully before purchase. |
| New Aftermarket (Adjustable) | $150 - $200 | For performance/lowered cars. Not needed for standard repairs. |
| Shop Labor | $100 - $225 | Typically 1.0 to 1.5 hours of labor per side. |
| Wheel Alignment | $80 - $200 | Required after replacement to prevent tire wear. |
Installation Overview & Difficulty
Replacing the rear upper control arm is a straightforward job for a DIY mechanic with some experience. Access is good compared to many other vehicles.
- Difficulty: 2 out of 5
- Estimated Time: 1-1.5 hours per side
- Tools Required: Jack, jack stands, socket set, torque wrench, pry bar.
Critical Step: Do not fully tighten the bolts for the control arm bushings until the vehicle's full weight is resting on the suspension. Lower the car onto ramps or place the jack under the lower control arm to compress the suspension to its normal ride height. Then, torque the bolts to specification. Tightening the bolts with the wheel hanging in the air will pre-load and destroy the new bushings in a very short time.
No Recalls or Technical Service Bulletins
As of mid-2024, there are no safety recalls or Technical Service Bulletins (TSBs) issued by Fiat, Chrysler, or the NHTSA specifically for the rear control arms on the 2017-2018 Fiat 124 Spider. Any failures are typically due to normal wear and tear.
Frequently Asked Questions (FAQ)
Can I use a rear upper control arm from a Mazda MX-5 Miata?
Yes, absolutely. The 2017-2018 Fiat 124 Spider shares its suspension with the 2016-2024 Mazda MX-5 (ND). The Mazda OEM part N243-28-20X is identical to the Fiat part and is usually much less expensive.
Do I really need a wheel alignment after replacing this part?
Yes. This control arm is a key part of setting the rear wheel alignment, specifically the camber angle. Skipping the alignment will cause rapid and uneven tire wear and can affect handling.
How do I make sure I'm buying the correct upper arm?
Look at the rear wheel assembly from the side of the car. You will see two control arms connecting the top of the wheel hub to the car's frame. This part is the one located towards the rear bumper (rearward). The other is the forward arm. They are not interchangeable.
Is it safe to drive with a bad rear control arm?
It is not recommended. While the wheel is unlikely to fall off, a badly worn control arm makes the vehicle's handling unpredictable, especially during emergency maneuvers or on slippery surfaces. The resulting alignment issues will also destroy your tires, making a small repair much more expensive. It should be repaired as soon as possible.
Technical Specifications
OEM Part Numbers: 68313926AA 68313178AA N243-28-20X N2432820X
Position: Rear Suspension, Upper Rearward. Also called: Upper Lateral Link. Material: Stamped Steel with rubber bushings.
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.
- Fiat 124 Spider:
- Understanding the Fiat 124 Spider & Mazda MX-5 Connection
- Symptoms of a Failing Rear Upper Control Arm
- How to Diagnose a Bad Rear Upper Control Arm
- Buying a Used Rear Upper Control Arm
- Cost Comparison for Rear Upper Control Arm Replacement
- Installation Overview & Difficulty
- No Recalls or Technical Service Bulletins
- Frequently Asked Questions (FAQ)
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