Mustang Slalom After

When Hotchkis Performance talks about suspension, we listen.

Hotchkis sent us this primer on updating the suspension on classic 1960s and ‘70s muscle cars to make them handle like a late model. According to Hotchkis, an upgraded suspension is not just a performance advantage, it’s also a safety issue on modified vehicles. The stock suspension—even one that’s completely rebuilt—cannot handle the big doses of horsepower, larger wheels, and modern performance tires we love to add to our vehicles. That can lead to serious handling and steering issues that can be dangerous on the street and downright deadly on the track.

5-Step Suspension Plan

Suspension design, engineering, and technology have come a long way since the 1960s and ‘70s when some of our favorite muscle cars were designed and built. Just about any modern car (even minivans!) can drive circles around a classic muscle car with an OEM suspension, even one that has been totally rebuilt. What’s more, that OEM suspension was not designed to deal with today’s big-horsepower engines and especially modern performance radial tires with stiff sidewalls. Those tires create increased cornering loads that cause the soft factory rubber bushings and control arms to flex. This flex can overload the power steering pump and force you to fight for control of the car.

Modern radial tires need an entirely different suspension geometry with ample negative camber and positive caster to work correctly. A well engineered performance suspension package, like the Hotchkis Total Vehicle System (more on that in the slide show below), can address handling problems in one fell swoop. But you can follow these steps and improve your handling as your budget allows without having to take the vehicle off the road:

  1. Replace any worn steering components like the ball joints, idler arm, center link, and tie rods.
  2. Add a matched set of front and rear sway bars and a good performance shock package. These will give you the immediate improvements in handling, control, and ride comfort.
  3. Add a performance spring package with higher than stock spring rates that lower the car for increased control and a modern, aggressive look.
  4. Address the suspension geometry with geometry-corrected front upper and lower A-arms, a bump steer control kit (when applicable), and a performance rear suspension package with adjustable upper trailing arms. These modifications will add positive caster, allow you to adjust static camber settings, and optimize rear pinion angle for enhanced grip and control.
  5. Add chassis braces to stiffen and support shock towers, the front subframe, suspension pickup points, and unibody structures so the car can better cope with the increased cornering loads the suspension upgrades are able to generate.

For drivers looking to extract every last bit of handling potential for autocross or track day events, adjustability is the key. Adjustable sway bars allow roll stiffness to be increased or decreased to match the driver’s preference for understeer, oversteer, or neutral handling. Well-tuned performance shocks dampen spring energy so the tires can maintain the optimum contact patch. Double- and even triple-adjustable shocks are available to further fine-tune handling and ride quality, but a good set of single- adjustable shocks that control rebound damping can do a good job and are more affordable.

In the end, the objective of a good performance suspension is to balance handling, braking, and acceleration, creating a car that is both fast and fun to drive instead of a white-knuckle experience that scares you every time you turn a corner.

Closer Looker: Hotchkis Total Vehicle Systems

suspension upgrade kit for 1964-66 ford mustang
vintage 1968 chevy camaro 327 RS
suspension upgrade kit for a 1968-70 GM A-Body
a vintage chevelle on a suspension test apparatus
classic chevy impala in a tight turn

Hotchkis makes TVS kits and suspension components for lots of 1960s-70s cars including first generation Mustangs (Stage 1 kit for 1964-66 shown here); Camaro/Firebird; Chevy II/Nova; 1978-87 GM A-/G-body; 1966-69 Dodge B-body; 1970-74 Challenger/Barracuda; 1967-76- Dart/Valiant; and 1963-72 Chevy/GMC pickup. Hotchkis also makes kits for 1982-2015 Camaro/Firebird and 2005-15 Dodge Magnum/Charger/Challenger.

Even when rebuilt to OEM specifications, a classic muscle car’s suspension is not capable of handling today’s horsepower levels and modern performance radial tires with stiff sidewalls. Those tires create increased cornering loads that cause the soft factory rubber bushings and control arms to flex, which can cause unsafe handling. Hotchkis’ Total Vehicle Systems (TVS) have everything you need to update your muscle car or GM truck’s suspension to handle 21st century levels of horsepower and tire technology

This is the Hotchkis Stage 2 TVS kit for 1968-70 GM A-body cars. It includes tubular front A-arms, adjustable upper/non-adjustable lower rear trailing arms, lowering springs, 1.5 Street Performance monotube shocks, tie rod ends, and required bushings and hardware. If you can’t swing an entire TVS kit at once, all of the components are available separately so you build your suspension in stages.

Hotchkis takes great pains to engineer and test suspension components. For example, it tests and tunes shocks on a shock dyno and this four-post shaker rig. The rig’s control computer uses various data sources and controls the impulse forces to each of the hydraulic actuators (one per post) Sensors mounted on the chassis monitor the vehicle’s dynamics and its reactions to the inputs. That makes the shaker rig a powerful tool for component testing.

Of course, not even the most sophisticated shop equipment can take the place of real-world evaluation. Hotchkis engineers practically live in their test vehicles doing skidpad testing, road racing, autocrossing, and lots of highway driving. That's how they can get barges like this ’64 Impala convertible around corners without acting like a swayback mule. Hotchkis makes sway bars, front A-arms, rear suspension kits, and other components for the 1960-69 full size Chevys.