G-Comp™ 68-72 GM A-Body Frame/Performance Chevelle Chassis

• Complete fabricated and boxed A-body replacement chassis is much stiffer than stock A-body frame
• G-Comp™ suspension replaces stock pickup points for no-compromise performance and superior geometry
• Dramatically lowered ride height lowers center of gravity for better cornering and aggressive appearance
• G-Comp™ Torque Arm rear suspension plants the rear axle without cutting up floor pans
• Fabricated uprights with extreme-duty G-Comp™ X rebuildable billet hubs up front and floater rear hubs handle tremendous side loads without deflection
• Rack-and-pinion steering for precise steering feel
• Front suspension easily adjustable for caster and camber to accommodate setup changes from track to street
• Rear suspension offers roll center, instant center, and pinion angle adjustment
• Designed for front and rear coilovers allow for even more adjustability
• Adjustable splined sway bars front and rear
• Body bolts on using stock mounting locations
• Utilizes stock SBC/BBC engine mounting locations, can easily fit LS family of engines with adapters
• Narrowed rear rails to allow for bigger tires with mini-tubs
• Designed and built in Lincoln, NE

The Ultimate Handling Upgrade for the ‘68-‘72 A-body

GM asked a lot of the ’68-’72 A-body chassis. From docile shopping mall creeping with the family packed into a Cutlass to spirited driving in big-block powered brutes like the GTO and LS6 Chevelle, one chassis had to do it all. And like any one-size-fits-all solution, there were some compromises. Those big-block Chevelles and Oldsmobile 442s handled better than their grocery-getting brethren, but GM could only do so much by tacking on heavier springs and sway bars. Not to mention the fact that they were working with 60’s technology and skinny bias-ply tires. 

Many of us in the years since our favorite muscle-era warriors rolled off the line have tried the bolt-on route to better handling. After all, technology has advanced quite a bit in the last 50 years and modern products like tubular control arms, coilover shocks, and big disc brakes go a long way toward making an A-body go around corners with some agility. But at the end of the day, these upgrades are still handcuffed by the archaic stock suspension pickup points and a stock chassis that’s been subjected to a half-century of fatigue and corrosion. Not to mention the fact that even a clean stock chassis is prone to some serious twisting and flexing if you ever can get the stock suspension to hook. It’s hard to wring truly modern performance out of a stock A-body chassis. 

Supercar Performance, Vintage Muscle Car Soul

There’s only one real solution for those who truly want their A-body to fly through the twisties like a new Corvette; a new chassis. The engineers at Speedway Motors went to the drawing board to marry the proven G-Comp™ performance suspension system to a fabricated A-body chassis that adds significantly more strength and rigidity to the equation than a stock frame could manage. Not to mention the fact that those antiquated suspension pickup points are long gone. Instead, that archaic stock geometry is completely replaced by the track-proven G-Comp™ architecture, designed to create and withstand the insane amounts of grip that modern Pro Touring cars are known for. 

In addition to the desire for added performance, folks have also been throwing parts at their old A-body chassis to try to get a lowered stance. These efforts are also often thwarted by the stock geometry just not wanting to cooperate with an in the weeds stance. G-Comp™ suspensions are low to bring the center of gravity down for better performance, and this Chevelle chassis is no exception. Our ’72 Chevelle test car had previously been lowered with bolt on suspension pieces, but when it hit the ground on this G-Comp™ chassis it was transformed from a mildly modified stocker to a fully dialed Pro Touring beast, looking ready to carve any curve we could throw at it. 

Optimal Camber to Keep the Tires Planted

Geometry is at the heart of G-Comp™. When GTOs and Chevelles were rolling off the production line, they were equipped with bias-ply tires and mere inches of rubber meeting the road. When pushed hard into a corner, the stock front suspension made matters worse, losing camber as it compressed and leaving the rolled-over tire hanging on for dear life. G-Comp™ front suspensions don’t make any compromises to that archaic design, instead they’re clean-sheet designs precisely engineered to make the most of modern pro-touring tires with wide tread and sticky compounds. G-Comp™ is engineered with optimal camber gain, meaning that as the suspension compresses in a hard corner, the top of the tire is pulled in, keeping that wide rubber planted to the pavement. And to keep that newfound traction from causing other issues, this chassis is equipped with stout fabricated uprights and the trick rebuildable 4140 billet G-Comp™ X Heavy Duty Hubs to resist deflection when extreme forces are applied. 

Rack-and-Pinion Steering Out of the Box

Rack-and-pinion steering is engineered into the G-Comp™ front suspension and the rack is included. A steering rack is lightweight, compact, and precise, offering quick and crisp steering feedback well suited to performance driving. That’s why the OE’s have been using them for decades. Because of all the benefits, installing a steering rack is a common upgrade to classic muscle cars, but care must be taken when installing a rack to the stock suspension. If the steering rack is not sized and positioned properly to work in concert with the suspension geometry, any improvement will be lost to nasty bump steer and dangerous handling. G-Comp™ suspensions are engineered with the rack-and-pinion where it needs to be to deliver safe, reliable, precise steering.

Torque Arm Rear Suspension for Maximum Grip

At the rear of this chassis is the G-Comp™ Torque Arm rear suspension. The engineers paid extra attention to the geometry when they designed this setup. The result is a suspension that plants the rear tires at launch, then remains neutral under deceleration and around corners. The long torque arm creates an instant center that doesn’t change drastically through suspension travel like a 4-link. And since every car is different, roll center and instant center are adjustable on the G-Comp™, allowing you to fine tune your A-body’s handling to match your setup and driving style. Pinion angle is adjustable with special serrated hardware and the splined sway bar is available in 11 different rates, with a 650-pound bar included in the kit. And like those hefty uprights and hubs in the front, the 60" 9-inch housing in this chassis utilizes 28.5" & 33" full-floating axles (Not Included) with strong billet hubs to resist deflection and potential brake pad knockback. 

Fully Bolt-On Installation

This kit has been verified to bolt up to the stock body mount locations, making it easy to ditch that archaic stock chassis without getting out the torch or cutoff wheel. G-Comp™ chassis are built in our state-of-the-art Lincoln, Nebraska manufacturing facility. Frames and control arms are welded in precision fixtures and billet components are CNC machined to exacting tolerances. Every kit is then verified to ensure it will fit your car and deliver on the promise of true bolt-in performance. They ship to you in bare steel, ready for paint or powdercoat in your desired color scheme. The stock SBC/BBC engine mounting points are retained and if you're looking to go the LS swap route simply add a pair of our LS billet motor mount adapters.

We know from firsthand experience how G-Comp™ can totally transform the character of an old muscle car. G-Comp™ suspensions were not just designed to work on paper. They have been extensively driven, raced, and abused in our own fleet of test cars by Team Speedway, who can be found most weekends at the autocross track, dodging cones and taking notes about how to make G-Comp™ suspensions better, stronger, and faster.

Recommended Shocks and Springs

Coilover shocks are a common upgrade for many classic muscle car owners looking for better performance. G-Comp™ suspensions are designed for coilovers, adding another dimension of adjustability and performance to the equation. 

Front: 

G-Comp™ front suspensions are designed for coilovers with a 12” mounted length and an 8” spring. Coilovers are not included with the G-Comp kit. Below are our recommendations:

AFCO Street/Pro-Touring Coilover Shock (non-adjustable)

AFCO Pro-Touring/Race Coilover Shock (single adjustable)

AFCO Max Performance/Race Coilover Shock (double adjustable)

Afco 8" Chrome Coilover Spring *Choose appropriate rate

Rear:

Rear shock length and spring rate will depend on how you set the car up (ride height, vehicle weight, ride stiffness, etc.).

The shock and spring package below is a good starting point:

AFCO 5/8" Bolt, 4" Stroke Pro Touring Fixed Valve Coil-Over Shock

AFCO 2-5/8" Coil-Over Springs *Choose appropriate rate 

Recommended Brakes

Brakes are not included with G-Comp™ suspensions, allowing you to choose a kit that will best suit your car and driving style.

Front: 

Below are some front brake options. The Economy kit is best suited to mild street driving, while the Wilwood kits are better suited for performance:

Speedway Motors Economy Disc Brake Kit

Wilwood 13" Brake Kit-Black Caliper

Wilwood 13" Brake Kit-Red Caliper

Rear: 

The floater rear axle housing includes caliper brackets that accept calipers with a 5.25" mounting spacing, such as the Wilwood Dynalite. Floater rear hubs accept 12.19" x 0.81" brake rotors with an 8 x 7.00" bolt pattern, such as the Speedway Motors Pro-Lite. Combine this caliper and rotor combo with Wilwood BP-10 Brake Pads for a complete rear brake setup. This brake combo is a great setup for street driving as well as entry-level autocross and road course competitions. 

For more extreme applications, consider the G-Comp™ X Rear Brake Kit that includes 4-piston Wilwood Dynalite calipers and aggressive brake pads.

Fits:

1968–1972 Chevelle

1968–1972 Cutlass, 442

1968–1972 Tempest, LeMans, GTO

1968–1972 Skylark, GS, Special

 

Will NOT fit:

4-doors or wagons

Monte Carlo or Grand Prix

El Camino