Building a gasser-style GM A-body car is a popular way to capture the classic early-1960s drag racing look while retaining modern performance. The suspension is the backbone of any gasser build, and choosing the right parts is crucial for both stance and function. This guide covers the key components you need to know for your GM A-body gasser suspension setup.
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Understanding the Gasser Suspension Layout
The gasser style originated in the early days of drag racing, where cars were modified for straight-line speed. A typical gasser features a raised front end, often with a solid front axle, and a lowered rear. For GM A-bodies (Chevelle, Tempest, F-85, and Skylark platforms from 1964-1972), this means swapping out the stock independent front suspension for a straight axle or using aftermarket components to achieve the classic rake.
Front Suspension: Straight Axle vs. Modified IFS
Most gasser enthusiasts opt for a straight front axle because of its simplicity and iconic look. For GM A-bodies, you can use a purpose-built gasser axle from brands like Speedway Motors or Chris Alston's Chassisworks. These axles are typically made from high-strength steel and include spindles, kingpins, and mounting brackets. You'll also need radius rods (also called ladder bars or split wishbones) to locate the axle and control braking torque. Many kits are available that include axle, radius rods, and required hardware.
An alternative is to modify the existing independent front suspension (IFS) to achieve a raised stance. This usually involves using taller springs, extenders, or drop spindles. However, purists argue that a true gasser has a solid axle. If you're on a budget or want better handling, a modified IFS can work, but it won't have the same visual impact as a straight axle.
Rear Suspension: Ladder Bars or Leaf Springs?
The rear suspension in a gasser GM A-body typically uses a ladder bar setup or monoplate leaf springs. Ladder bars (traction bars) help control axle hop and improve traction during hard launches. They are adjustable and pair well with coilover shocks. Many kits are available that bolt into the existing leaf spring mounting points. Alternatively, you can keep the stock leaf springs but add slapper bars or traction bars for improved bite.
For the ultimate gasser look, many builders use a reverse-rotation rear axle or a narrowed rear end to tuck wider rear tires. This requires new axle housing, axles, and possibly a coilover conversion kit.
Key Components for Your GM A-Body Gasser Suspension
1. Front Axle Assembly
A typical gasser front axle for a GM A-body is about 59 inches wide (from hub face to hub face). It comes with spindles, kingpins, and tie rod mounts. You'll need to fabricate or purchase a crossmember that replaces the stock suspension mounts. Many kits include a crossmember that bolts in with minimal welding.
- Material: Look for 1020 DOM steel tubing or 4140 chromoly for strength.
- Spindles: Use standard Ford-style kingpin spindles (like 1949-1968 Ford) because they are widely available and have good brake options.
- Brakes : Most gasser axles use manual disc brakes from brands like Wilwood or Aerospace Components. You'll need a master cylinder with a manual proportioning valve.
2. Radius Rods and Mounts
Radius rods control fore-aft movement of the axle. Common types are split wishbones (two rods attached to the frame rails) or a single ladder bar style. For GM A-bodies, stock-style split wishbones were used on early cars, but aftermarket ladder bars are easier to adjust and more common.
- Heim joints: Use 3/4-inch heim joints for strength.
- Frame mounts: Weld-on or bolt-on brackets that attach to the frame near the firewall.
3. Coilover Shocks vs. Leaf Springs
Coilover shocks are popular for gasser front ends because they allow ride height adjustment and better dampening. For the front, use coilovers with a spring rate around 175-225 lbs/in (depending on engine weight). For the rear, coilovers with around 200-250 lbs/in work well.
If you're keeping leaf springs, consider adding a set of traction bars to control axle wrap. Calvert Racing or Southside Machine make good options for GM A-bodies.
4. Steering Linkage
A straight axle requires a different steering setup. You'll need a cross-steer system that mounts a drag link and tie rods to the frame. Some kits include a steering arm that attaches to the axle. Use a manual steering box (like a 605 or 808 box) for the gasser feel.
Practical Considerations for Your Build
Suspension Geometry
A gasser typically has positive caster (around 5-7 degrees) to keep the wheels stable. Also, a kingpin inclination of about 8-10 degrees is common. If you're building from scratch, get a front-end alignment guide from the manufacturer.
Ride Height and Rake
The classic gasser rake is about 3-4 inches higher in the front than the rear. With a straight axle, you can achieve this by adjusting coilover spring perches or adding spacer blocks under the leaf springs.
Tires and Wheels
- Front: Narrow tires (like 145R15 or bias-ply repros) to reduce rolling resistance.
- Rear: Wide slicks (like 10.5W or 11.5W bias-ply or radial drag tires). You may need a narrowed rear end to fit them inside the fenders.
Recommended Parts Kits for GM A-Body Gassers
To simplify your build, several companies offer bolt-on (or mostly bolt-on) kits:
- Speedway Motors Front Gasser Axle Kit: Includes axle, spindles, kingpins, radius rods, and mounting brackets. Designed for 1964-1972 A-bodies.
- Chris Alston's Chassisworks Straight Axle Kit: High-quality chromoly parts with adjustable coilovers.
- Northwest Gasser Front End Kit: A cost-effective option with 1.5-inch tube axle.
For the rear, consider:
- Calvert Racing Cal-Split Monoleafs: Mono-leaf springs with adjustable traction bars.
- Southside Machine Ladder Bars: Bolt-on design for stock leaf springs.
Final Recommendation
If you're building a GM A-body gasser on a budget, start with a complete front axle kit from Speedway Motors. It provides everything you need for the front, including axle, radius rods, and mounting brackets. For the rear, an adjustable ladder bar kit paired with coilovers offers the best adjustability and traction for drag racing. Keep in mind that any gasser build requires some fabrication and welding skills. Don't forget to upgrade your brakes and steering box to handle the new setup. With the right parts and careful installation, your gasser will turn heads at the track and on the street.