Hair Pin Suspension Parts: A Complete Guide to Choosing and Using Them

Hair pin suspension parts are a specialized component found in certain high-performance and classic vehicles. They offer unique characteristics that set them apart from conventional coil springs or leaf springs. This guide explains what hairpin suspension parts are, how they function, and what to consider if you are planning to use them in your project.

What Are Hair Pin Suspension Parts?

Hair pin suspension parts refer to the coil springs shaped like a hairpin—a long, narrow coil that loops back on itself. Unlike standard coil springs that are evenly wound, hairpin springs have a distinctive “U” or “V” shape with closely spaced coils at one end and more widely spaced coils at the other. This design allows the spring to provide a progressive rate: it is softer during initial compression and becomes stiffer as it compresses further. These parts are often used in the suspension systems of racing cars, hot rods, and some vintage automobiles.

Key Components

Hairpin suspension systems include:

• Hairpin Springs: The primary spring element, typically made from high-grade alloy steel.
• Spring Perches: Mounting points that secure the spring to the chassis and axle.
• Shock Absorbers: Dampers that control spring oscillations; often mounted inside or alongside the spring.
• Control Arms: Linkages that guide the wheel’s movement while maintaining proper geometry.
• Bushings and Hardware: Rubber or polyurethane bushings reduce noise and vibration.

How Hairpin Suspension Works

Hairpin springs work by twisting along their length rather than compressing axially like a standard coil. When the wheel hits a bump, the arms of the hairpin spread apart, storing energy. The progressive rate means that small bumps are absorbed softly, while larger impacts are met with increasing resistance, preventing bottoming out. This design also allows for a lower ride height without sacrificing suspension travel, making it popular in lowered or customized vehicles.

Progressive Spring Rate

A key advantage is the progressive spring rate. Early in compression, the closely spaced coils contact each other, effectively reducing the number of active coils and stiffening the spring. This provides a comfortable ride under normal conditions and firm support during hard cornering or braking.

Benefits and Drawbacks

Advantages

• Progressive Rate: Improves ride quality and handling balance.
• Compact Design: Fits in tight spaces where conventional springs won’t.
• Adjustable Preload: Many hairpin setups allow preload adjustment via threaded perches.
• Lightweight: Typically lighter than multi-leaf spring packs.

Disadvantages

• Complexity: More components to set up correctly.
• Cost: Higher than many standard spring options.
• Specialized Knowledge: Requires careful selection and tuning.
• Limited Availability: Not as common as coilovers or leaf springs.

Applications

Hairpin suspension parts are most often found in:

• Hot Rods and Customs: Front suspensions on traditional hot rods often use hairpin springs for a classic look and improved ride.
• Vintage Racing Cars: Many early race cars (e.g., MG T-type, Porsche 356) used hairpin front suspensions.
• Off-Road Vehicles: Some rock crawlers and buggies use hairpin springs for extreme articulation.
• Motorcycles: Certain vintage motorcycles have hairpin sprung seats or front ends.

Choosing the Right Hair Pin Suspension Parts

Selecting hairpin suspension parts involves several considerations:

Spring Rate

Determine the vehicle weight and desired handling. A common formula is to aim for a natural frequency of about 1.0–1.5 Hz for street use and 1.5–2.5 Hz for track use. Consult a spring rate calculator or a suspension specialist.

Length and Travel

Measure the available space for the spring. Hairpin springs come in various lengths and free heights. Ensure the spring can accommodate the full range of wheel travel without coil bind (when coils touch) or sagging.

Material and Coating

Most springs are made of chrome silicon or chrome vanadium steel. Look for powder coating or zinc plating to resist corrosion, especially if the vehicle is driven in wet conditions.

Mounting Hardware

Check that spring perches (top and bottom) match the spring diameter and have proper strength. Many aftermarket kits include adjustable perches for ride height tuning.

Compatibility with Shock Absorbers

Hairpin springs often require a shock absorber mounted inside or alongside. Some kits come with matched shocks, or you can select aftermarket shocks with the correct stroke and damping.

Installation Tips

1. Safety First: Compress springs using a proper spring compressor. Do not use makeshift tools.
2. Measure Carefully: Mock up the suspension with the spring installed but not fully compressed to check clearances.
3. Torque Specs: Use manufacturer torque values for all fasteners, especially control arm bolts.
4. Alignment: After installation, get a professional four-wheel alignment to maximize tire life and handling.
5. Break-In: Drive gently for the first 100–200 miles to allow the springs to settle, then re-check ride height and tighten any loose hardware.

Final Recommendation

Hairpin suspension parts are an excellent choice for enthusiasts building a vintage-inspired or custom vehicle that demands a unique look and progressive spring characteristics. They are not ideal for everyday daily drivers due to cost and complexity, but for a weekend toy or show car, they offer a blend of style and performance. If you decide to go this route, purchase from reputable manufacturers like Speedway Motors or QA1 (avoiding generic unnamed brands). Work with a suspension shop experienced in hairpin setups to ensure correct spring rates and geometry. With proper selection and installation, hairpin suspension can transform your car’s ride and handling.