Leaf-Springs Suspension Systems - Hook Hard On Leaf Springs

Stick the power to the ground using these simple tips.

From the March, 2012 issue of Chevy High Performance

By Michael Galimi

Horsepower and torque are useless unless you can apply the energy to the ground in order to accelerate your muscle car. Traction becomes quite a challenge for those dealing with leaf-spring rear suspension systems found under older Chevy vehicles. Leaf-spring suspension systems are simple and effective for its intended purpose—but add some power and sticky tires and the story changes. Ron Rhodes, of Rhodes Custom Auto, knows a thing or two about this setup and shared some secrets that are employed on his ’68 Camaro RS. Rhodes is no stranger to the dragstrip life as he has fought hard on the asphalt jungle for decades and most recently is one of the top X275 players in the Northeast. The X275 ranks are reserved for stock suspension cars running 275 drag radials, and the competition is fierce. But that isn’t his only foray into the wild heads-up racing world, as he is also a former NMCA badass in the naturally aspirated Pro Stock division.

Under the hood, Rhodes relies on a 414ci small-block Chevy with RHS 23-degree cylinder heads. He assembles the engine in-house at his shop but credits Bischoff Engine Service (BES) for the combination and machine work. The task of hooking over 1,000 nitrous-assisted horsepower rests in the hands of a leaf-spring setup. It isn’t the ideal combination for drag racing but one that Rhodes was determined to make effective. After all, most of the cars competing in the category are Fox-body Mustangs with a unique, factory-style, four-link rear suspension—advantage: Mustang. Rhodes turned to Calvert for a set of its CalTracs and a pair of the company’s split mono springs. He combined the bars with some other little tricks he’s learned over the years. The results are an outstanding 1.17 60-foot on the 275 drag radials at a race weight of 2,900 pounds.

Leaf-spring suspensions are a simple design and utilize a single or multiple leaf that is mounted to rearend housing. The problem arises when traction and power are inserted into the equation. The leaf springs want to wrap the front half into an S-shape. Once it takes the S-shape, the spring will then deflect back to its original form, causing tire shake. The tire shake is detrimental to suspension and driveline components, which oftentimes crack, bend, and break under these stresses. The CalTracs bars help stabilize the leaf springs and prevent it from wrapping up due to the axle twist at launch. Rhodes also relies on the split mono springs from Calvert because it allows him to adjust the ride height, unlike stock or factory replacement-style leaves. The different ride height allows the car to transfer better and offers more stability at high speeds.

In addition to the CalTracs, Rhodes tapped a pair of Ranchero shocks, relocated the shock mounts, and added an antiroll bar. The Ranchero shocks are an unusual name in a drag racing application but Rhodes says they work very well. He does have a set of adjustable Santhuff shocks that he is going to start testing for the 2012 season. The antisway bar is used to control the body lift and twist. In drag racing the body wants to separate as the rearend twists, and the tires are driven into the ground. That is the gap between the driver-side rear-wheel opening and the tire. An antiroll bar helps keep the body straight and rigid so the tires are loaded equally.