POINT & SHOOT
Making That Musclecar Handle
During a recent conversation with an industry professional we got around to the subject of making old musclecars handle like new cars. "It's pretty simple," he said, "Install a quick-ratio power steering box, new springs, polyurethane bushings, and some fat wheels and tires, and you'd be surprised at how responsive an old car could be. You really can improve the handling of any car with the addition of some trick new steering components, suspension components, and the right tires and wheels."
Most of our favorites were built at a time when handling was far a main consideration. Thirty years ago, straight-line get-up-and-go was all it took to sell cars, so the manufacturers concentrated on muscle. It was also around that time that power steering became a must-have performance option, even though it was still considered a "luxury" item. Even then, however, most musclecars came with a power steering setup that was about as useful as breasts on a bull. Thankfully, in this day and age there's a plethora of bolt-on steering components made for just about every car.
In order to get better handling and a quicker response from our classic Chevy the first thing we need is a better steering box. "What makes a steering box better than another", you may be asking? Well, it's a matter of ratio. Stock boxes usually sport a ratio of around 16 or 17:1, some could even be as much as 20:1, but don't be fooled, in this case more is definitely not better. Aftermarket or performance boxes are usually around 12:1. What does that mean? Simply put, a 12:1 steering box is "faster," it'll translate more steering wheel movement to the front tires than a 20:1 box would. So when you turn the wheel a quarter turn with a 12:1 box, the front wheels will move further than they would with that same quarter-turn with a 20:1 ratio box.
The same theory holds true with most rack-and-pinion steering systems found in performance cars today. Most stock racks use around a 13:1 ratio, but performance aftermarket racks can be ordered with anywhere from an 18 to 4:1 ratio, again, a heck of a lot quicker than stock. The rack-and-pinion's compact and lightweight design makes it a very easy-to-package system that's good for high-performance driving, as well.
One problem with using high-performance power steering racks and boxes in early cars has been finding the right power steering pump to do the job. Today there are plenty of pumps to choose from, but adapting a late-model pump to an early musclecar used to require custom fabrication. Many aftermarket companies have addressed that problem and now it's an easy swap to do. There are bolt-on brackets and pulleys available, and many sources provide high-pressure hoses to make the swap, as well.
The finishing touch for a new steering system comes from the use of a new collapsible steering shaft along with a vibration-reducing U-joint to get rid of that worn-out old rag joint. Though available in numerous lengths more than likely an aftermarket shaft will require cutting to fit. It's also wise to drill a few locating dimples for each of the shaft's set screws to help secure the shaft in place. The nice thing about these shafts is they're smaller and lighter than the clunky stock pieces, making spark plug and header clearance easier to deal with.
Updating your old steering components and installing some new high-tech parts is a bit more than an afternoon job, but the effort can make any classic Chevy handle tremendously better than it did.
STEERING SYSTEMS EXPLAINED
The Same Thing, But Different
Steering and suspension are two automotive systems that perform different functions yet are directly related. Each one exerts such an extreme amount of control over the other that it's rare one is mentioned without reference to the other. Let's start out by taking a look at the steering system.
When it comes to getting your musclecar to head in the direction you want it to, there's two basic systems that'll get the job done: mechanical gear (sometimes referred to as recirculating ball) and rack-and-pinion steering. Both can be found in either manual or power-assisted versions.
Standard mechanical steering uses a series of arms and links connecting both front wheel assemblies so they move in unison. In a steering box, the input shaft turns a worm gear that, in turn, causes a toothed metal block to move back and forth. Ball bearings in a recirculating track reduce the friction between the worm gear and the block. As the block moves, its teeth rotate a gear connected to a shaft (the Pitman shaft), which then, via the Pitman arm, moves the balance of the steering linkage, and hence, turns the front wheels. In a nutshell, here's the whole picture: the steering wheel is connected to a shaft (the column), at the other end of the shaft is the box. The steering box has an arm attached to the output shaft called the Pitman arm. The Pitman arm is connected to one end of the center (or drag) link. At the other end of the link is an idler (a fixed pivot point), between the idler and the Pitman arm the centerlink is supported in the correct position to keep both front wheels moving in unison.
Attached to either end of the centerlink are inner tie rods that provide pivot points for the steering gear. At the opposite end of threaded tubes called sleeves are, as the name implies, outer tie rod ends (the threaded sleeves allow the tie rod ends to be adjusted in or out as needed so that the wheels can be aligned). The outer tie rod ends are connected to the spindle assemblies that actually turn the wheels. The spindles (or knuckles as they're sometimes called) are connected to control arms via upper and lower ball joints creating the geometry of the steering axis.
See, it's not so complicated. It's just a simple connection between the steering wheel and the front wheels of the vehicle. In the mechanical system the weakness falls at the pivot points. The pivots are ball and socket joints that do, over time, wear out and require replacement. Worn steering parts degrade handling and promote premature tire wear, as well.
RACK & PINION
Though it performs the same job, rack-and-pinion steering does the task in a different manner. Basically, it combines the steering box and center link into one unit. Like mechanical steering, the wheel is connected to the rack-and-pinion via the steering column. At the base of the column (inside the R&P assembly) is a vertical gear called a pinion. The pinion rotates with the steering wheel (via the column) and its teeth mesh with a horizontal toothed shaft called a rack. As the pinion rotates it in turn moves the rack back and forth (left and right). Attached to each end of the rack are threaded rods (inner tie rods) to which the outer tie rods are connected. Again, like mechanical steering, the outer tie rods connect to the spindles (knuckles) holding the wheels.
One of the advantages rack-and-pinion steering has over its mechanical counterpart is that its more precise--in other words, input rotation is interpreted and transferred with virtually no "slop" or wasted energy because it makes use of significantly fewer parts and pivot points than that of standard "box" mechanical systems. This precision translates into much more responsive steering action.