Prothane 4-1705 Rear Coil Spring Isolator Kit Upper & Lower - Polyurethane

The Prothane 4-1705 is a rear coil spring isolator kit that includes both upper and lower isolators, providing a complete replacement for worn factory rubber units. The kit contains 4 polyurethane rear coil spring isolators (Prothane part 61909) and is available in your choice of red or black.

Coil spring isolators serve two critical roles in the suspension system: they dampen residual vibrations and road noise that pass through the coil springs, and they protect the control arms from direct metal-to-spring contact. Over time, the OEM rubber isolators crack, compress, and deteriorate under the constant shifting load — resulting in increased cabin noise, clunking, and reduced ride quality. Prothane's polyurethane construction resists this degradation, delivering a significantly longer service life than factory rubber components.

Key Features:

• Complete kit includes 4 rear coil spring isolators — both upper and lower positions
• Polyurethane construction — far more durable than OEM rubber under constant load and pressure
• Available in red or black (black version includes graphite additive for additional squeak resistance)
• Reduces coil spring noise and vibration transmitted into the cabin
• Protects control arms from direct coil spring contact
• Direct OEM replacement design — no modifications required
• Backed by Prothane's lifetime warranty against defects in materials and workmanship

For best results and to prevent squeaking, lubricate each isolator thoroughly with a polyurethane-compatible grease during installation. Prothane Super Grease (19-1750-001) is recommended.