Properly installing the YIKONG YK4107 RC Car Parts Rear Upper Linkage (Part No. 21086) helps maintain accurate rear axle alignment, improves suspension stability, and enhances off-road handling and climbing performance. This upgrade part is compatible with both the YIKONG YK4107 and YK4107 Pro.

What Should You Prepare Before Installing the YIKONG YK4107 RC Car Rear Upper Linkage?
Preparing the proper tools and disconnecting the battery before installation makes the process safer and helps prevent damage to your YIKONG YK4107 RC Car.
Recommended tools:
- Hex driver
- Needle-nose pliers (optional)
- Blue thread-locking compound (recommended for metal-to-metal screws)
Before starting, turn off your YIKONG YK4107 RC Car and disconnect the battery.
How to Remove the Original Rear Upper Linkage?
It is recommended to remove one side at a time to keep the rear axle properly aligned during the replacement process.
Follow these steps:
Step 1: Remove the Mounting Screws
Use the appropriate hex driver to remove the mounting screws from both ends of the Rear Upper Linkage.
Store the removed screws safely to avoid losing them.
Step 2: Remove the Original Rear Upper Linkage
Carefully detach the original Rear Upper Linkage from the rod ends.
If the ball ends fit tightly, gently wiggle them loose instead of forcing them to avoid damaging the ball cups or mounting points.
How to Install the Rear Upper Linkage (83mm)?
Make sure the linkage is installed in the correct position and orientation to maintain proper rear suspension geometry on your YIKONG YK4107 RC Car.
Step 1: Verify the Part
Confirm that you are installing the 83mm Rear Upper Linkage (Part No. 21086).
Do not mix it with linkage rods of different lengths.
Step 2: Connect Both Ends
Attach both ends of the linkage to:
- The rear axle mounting point
- The chassis mounting point
Ensure the rod ends move freely without binding.
Step 3: Tighten the Screws
Tighten both mounting screws evenly.
If the screws thread into metal parts, apply a small amount of blue thread-locking compound to help prevent loosening during off-road driving.
What Should You Check After Installation?
After installation, inspect the rear suspension and linkage movement to ensure your YIKONG YK4107 RC Car performs properly.
Check the following:
- Both linkage rods are installed correctly.
- The rod ends move freely.
- All screws are securely tightened.
- The rear axle is properly centered.
- Suspension travel is smooth.
- There is no abnormal looseness or unusual noise.
Complete a low-speed test drive before normal operation.

FAQ
Q1: Which models is the Rear Upper Linkage (21086) compatible with?
This upgrade part is compatible with the YIKONG YK4107 RC Car and YIKONG YK4107 Pro.
Q2: Do I need to adjust the linkage length during installation?
No. The linkage has a fixed length of 83mm and is designed to fit the factory mounting points without adjustment.
Q3: What should I do if the rear axle is misaligned after installation?
Check that both linkage rods are installed correctly, the rod ends are fully seated, and both sides are mounted symmetrically.
Q4: Should I use thread-locking compound?
Yes. If the screws are installed into metal threads, applying a small amount of blue thread-locking compound is recommended to help prevent the screws from loosening due to vibration.
Product Specifications
| Item | Specification |
|---|---|
| Product Name | Rear Upper Linkage |
| Part Number | 21086 |
| Compatible Models | YIKONG YK4107 RC Car, YK4107 Pro |
| Part Type | Upgrade Parts |
| Length | 83mm |
| Package Quantity | 2pcs |
Conclusion
Installing the YIKONG YK4107 RC Car Rear Upper Linkage (21086) is a straightforward upgrade, but proper installation is essential. Ensuring the correct linkage orientation, secure rod-end connections, and evenly tightened screws will improve rear axle stability, suspension geometry, and overall off-road handling, allowing your YIKONG YK4107 RC Car to perform more reliably on challenging terrain.
