RC car parts that fail most often? Every RC car, no matter how expensive, has parts that wear out faster than others. Knowing which parts fail most often and keeping spares on hand means you spend less time waiting for parts and more time driving. Here’s the complete guide to the most common RC car failures and how to deal with them.
RC car parts that fail most often
1. Spur Gear
Failure rate: Very high the most commonly replaced part in any RC car.
Why it fails: The spur gear is the large main gear that meshes with the pinion on the motor. It’s made of plastic (even on expensive cars) and takes the full shock load of throttle, direction changes, and crashes. High-power brushless setups chew through spur gears especially fast.
Signs it’s failing: A loud grinding or clicking during acceleration, loss of power, or the car stops moving while the motor still spins.
Fix: Replace the spur gear. This is considered a consumable part like brake pads on a real car. Always keep 1–2 spare spur gears in your toolbox. They cost $3–$10 each.
Longevity tip: Correct pinion-to-spur mesh is the single most important factor in spur gear life. Set it correctly (paper-thickness gap) and replace it before the teeth are visibly worn down.
2. Wheel Bearings
Failure rate: High, especially for bashers who drive on dirt, gravel, and wet surfaces.
Why they fail: RC car bearings are small stainless steel ball bearings sealed with rubber shields. They rust when exposed to water and mud, and eventually become rough, noisy, or seized.
Signs they’re failing: A rough, grinding, or vibrating feel when spinning the wheels by hand; a humming sound at speed.
Fix: Replace all four wheel bearings (and any other bearings in the drivetrain) with a full bearing kit. A complete set costs $5–$15. It’s faster and cheaper to replace all at once rather than one at a time.
Longevity tip: After every wet run, blow out bearings with compressed air and add a drop of light bearing oil. This dramatically extends bearing life.
3. Body Clips (also called body pins)
Failure rate: Extremely high these are literally designed to pop off in crashes.
Why they fail: The small R-shaped metal clips that hold the body shell on are intentionally lightweight so they pop off instead of breaking the body shell in a crash. They fly off and get lost constantly.
Fix: Buy a large pack of body clips ($2–$5 for 50 clips) and always have a handful in your toolbox. This is such a common failure that many hobbyists tape a spare to the inside of the body shell.
4. Wheel Hex and Wheel Nuts
Failure rate: Moderate-high.
Why they fail: The hex adapter that connects the wheel to the axle can crack or round out. Wheel nuts can vibrate loose and get lost.
Fix: Check wheel nuts before every run with a nut driver. Keep spare hexes and nuts they’re very cheap in multipacks.
Longevity tip: Add a very small amount of threadlock (Loctite Blue) to wheel nuts and let it cure for 24 hours before running. This prevents vibration loosening without locking them permanently.
5. Shock Seals and Shock Oil
Failure rate: Moderate more common with age and use.
Why they fail: The rubber O-rings in shock absorbers dry out, crack, or get damaged. When they fail, shock oil leaks out and the shocks stop working (the suspension becomes stiff and harsh).
Signs: Oily residue around the shock body; the shock feels stiff with no damping.
Fix: Rebuild the shocks with a rebuild kit ($2–$5) including new O-rings and fresh shock oil. Many hobbyists do this annually as preventive maintenance.
6. Servo Horn and Servo Saver
Failure rate: Moderate usually from crashes that force the steering past its limits.
Why they fail: The servo horn is the plastic arm attached to the servo output. In a crash, the steering system takes an impact load that can strip the servo horn’s teeth or snap it.
Fix: Replace the servo horn. They’re inexpensive ($1–$5). Keep two or three in your spares kit. Servo savers (spring-loaded servo horns that absorb impact) reduce this failure significantly.
7. A-Arms / Suspension Arms
Failure rate: Moderate depends on driving style.
Why they fail: Hard crashes bend or snap the suspension arms (also called lower/upper A-arms or wishbones). Cheap plastic arms on budget cars fail readily; quality plastics on premium cars are more resilient.
Fix: Replace with stock parts or upgrade to aluminum arms for longevity. Check if stock or aluminum arms are appropriate aluminum arms are stronger but transfer crash force to other (more expensive) components.
8. Steering Tie Rods and Turnbuckles
Failure rate: Low-moderate.
Why they fail: Tie rods and turnbuckles connect the steering servo to the wheel hub. In a hard crash, they can bend or snap. Bent turnbuckles cause the steering to track crooked even when the wheel is centered.
Fix: Check for bends by rolling the car slowly on a flat surface it should track straight. Replace any bent rods. Upgrade to aluminum or steel if available.
9. Driveshafts and CVD Joints
Failure rate: Low but when they go, the car stops moving immediately.
Why they fail: Driveshafts break in hard landings, aggressive direction changes, or from worn bone ends in the CVD joint. The plastic dog-bone style is most vulnerable; metal CVD shafts are significantly stronger.
Signs: The car pulls strongly to one side, or a wheel doesn’t spin despite the motor running.
Fix: Replace with metal driveshafts or CVD joints. Worth upgrading from stock plastic on any car you bash aggressively.
10. Pinion Gear Set Screw
Failure rate: Very common in new builds and after maintenance.
Why it fails: The tiny set screw that holds the pinion gear on the motor shaft vibrates loose. When it loosens, the pinion spins freely on the shaft instead of driving the spur gear exactly as if the gearbox were slipping.
Fix: Tighten with the correct hex key, then add a drop of Loctite Blue. Check this before every session.
Recommended Spare Parts Kit
Every RC driver should have these on hand:
- 2x spur gears (matching your car’s pitch and tooth count)
- 1x full bearing kit
- 10x body clips
- 2x servo horns
- 1x set of wheel hexes and nuts
- 1x shock rebuild kit
- 1x set of A-arms (at least one pair of fronts)
- Loctite Blue threadlock
- Bearing oil
Total cost: $30–$60 depending on your car brand.
Final Thoughts
Knowing what breaks, when it breaks, and why gives you a huge advantage as an RC hobbyist. You’ll spend less time frustrated and more time driving. Build your spares kit around the items in this guide, check your pinion mesh and wheel nuts before every run, and treat maintenance as part of the hobby rather than an interruption to it. The more you understand your car, the more you’ll enjoy it.
Frequently Asked Questions (FAQ)
How often should I replace spur and pinion gears?
Inspect after every 5–10 sessions. Replace when you see visible tooth wear, rounding, or damage.
Are metal gears worth the upgrade?
For spur gears, sometimes but be cautious. Metal spur gears can cause the motor pinion to wear faster. A good quality plastic spur gear with the correct mesh is often better.
How do I know if a bearing is bad without spinning the wheel?
Remove the wheel and spin the axle with your fingers. A bad bearing will feel rough, gritty, or tight. A good bearing spins smoothly and freely.
My A-arms keep breaking. Is my car too powerful?
Possibly. But it’s more often a geometry issue (arms at a bad angle from a previous crash) or low-quality arms. Check that the car’s geometry is still correct after crashes.
Can I use WD-40 on RC car bearings?
No. WD-40 is a water displacer, not a lubricant. It will temporarily improve a bearing but washes out all the remaining grease and accelerates wear.
How long do RC car shocks last before needing rebuild?
Depends on usage and conditions. Many enthusiasts rebuild shocks annually or whenever they notice oil leaking. Shocks used in mud and water may need more frequent attention.
My car drives in circles even with the steering centered. What failed?
A bent tie rod or turnbuckle is the most common cause. Roll the car on a flat surface to confirm, then inspect and replace.