Extremely stiff FK uniballs are normal, especially with new PTFE-lined bearings (often designated as F1 or F2 fitment), which are designed to be tight to prevent play. They often require significant force or leverage, such as a steel bar through the bore, to move initially.
Here is a breakdown of why they are stiff and how to address it based on technical specifications:
Why FK Uniballs are Stiff
• Tolerance Levels (F1/F2): FK PTFE-lined bearings come in different tolerances. F1 is extremely tight, while F2 (standard) is moderately tight.
• PTFE Liner: The Teflon (PTFE) liner is designed for a precise fit to prevent wobble in high-performance applications.
• New Condition: New rod ends or uniballs are intentionally stiff and will wear in over time.
• Contamination/Binding: If they have become seized over time, it may be due to dirt ingress, as they are not sealed like factory ball joints.
How to Address Stiff Uniballs
• Lubrication: Use a dry PTFE lubricant (e.g., CRC Dry PTFE, Tri-Flow).
• Do Not Use Oil/Grease: Avoid petroleum-based lubricants or WD-40, which can ruin the PTFE liner and attract dirt, causing further stiffening.
• Break-in Period: Use a bar through the bearing to manually move it to break in the lining.
• Check for Binding: Ensure the misalignment spacers are not binding at full suspension drop (maximum angle).
