Seats & Belts
You can’t control a vehicle well if you’re also trying to hold yourself in the seat. Ideally, your hands should only be doing one thing on the wheel: controlling the direction of the car, not also holding you in place. Unfortunately, the American automotive industry didn’t really embrace effective thigh and thorax bolsters on seats until sometime in the late ’70s to early ’80s, and even then it was a lame effort. Pretty much every bucket seat prior to then would allow your seat and shoulders to slide from side to side in the corners. If you take your turns with leisurely speed, it may not be that apparent, but try an aggressive corner and it’ll quickly become obvious.
The level of seat you need will be dictated by how fast your car is through a corner and how aggressively you plan on driving it, but bare minimum you want a seat with side and bottom bolsters at least 2-3 inches taller than the cushion. We encourage high-back seats for safety reasons as well as performance, but if you want to stay low-back, Corbeau and Kirkey have excellent options that look era-appropriate.
The next step is a four-point (or more) harness. It’s hard to describe how much of a difference this makes to someone who has never used them, but it’s night and day. Two- and three-point belts lack the upper body control that a four-point offers. Once you’re fully strapped in tightly where you don’t slide at all, you’ll be free to do nothing other than concentrate on driving.
Springs & Shocks
When you’re ready to really get your vintage car into the handling realm of modern cars, or far beyond into the realm of serious handling machines, a proper spring and shock combination sits at the top of the stack of must-have parts. Complete books have been written on the subject, and we recommend you pick up a few to really understand the considerations, but we can give you a brief primer.
All but the most aggressive factory cars rode on springs that were designed with very soft rates to provide smooth, cushy rides for the masses. They were also typically very tall to provide ground clearance for all manner of road conditions at the cost of raising the vehicles center of gravity. What we’re trying to do with performance springs is increase the rate of the spring (i.e. from 350 lb/in to 600 lb/in) to resist the transfer of weight from the side of the vehicle to the other during cornering and evasive maneuvers. The stability part is obvious; it’s much easier to control a mass that’s not teetering back and forth. The traction part may not be as obvious, but it’s a key component. For maximum grip, we want all four tires providing as much traction as possible, which they cannot do if too much weight is applied or lifted (due to body roll) during a corner. Increasing the rate of the coil springs will diminish the weight transfer, and using lowering springs will bring the vehicle’s center of gravity lower, which will also help diminish roll.
Equally important in the equation is a good pair of shocks that can effectively dampen the action of the spring on both compression and rebound. For most enthusiasts, single or nonadjustable quality shocks will do the trick, but for those seeking maximum tunability for their suspension, double adjustable or better is highly recommended.
Unless you have a factory-prepped racer such as a Shelby Mustang, Z/28 Camaro, or AAR ’Cuda, you’ve probably got one very dinky sway bar up front, and maybe none in the rear. For example, a stock front bar on an early Mustang is a puny ⅝ inch that can’t resist very much body roll. At least those cars are pretty light; we’ve seen bars that small on much heftier cars. A sway bar is effectively a torsion bar that is working to reduce the transfer of weight to the outside tire in a turn and keep the inside tires firmly planted to increase grip. While you can also reduce body roll through very stiff springs, sway bars allow you to accomplish the same effect without creating a bone-jarring ride. There is no firm formula for determining exactly how stiff your sway bar (or bars) should be since it varies depending on the car’s weight, parts combo, intended use, and driver preference. Fortunately, most aftermarket companies that make upgraded bars have done some homework for you and will offer bars that will not only be a definite improvement over stock, but that will be cost effective, and easy to install (Hotchkis is shown).