There is no such thing as “impossible” with classic and muscle cars anymore—just glance through the features and ads in any issue of PHR and check out the unbelievable list of parts available. If you can point at it on your car, someone probably makes an improved version of it. On one level that spoil of riches is great, but it can also be overwhelming when planning what to do with your car and where to spend your hard earned money.
Nowadays the sky truly is the limit. Or said another way, performance still costs money, and you’ll need to choose exactly what level of modern car you want to match. You can go crazy with custom stuff (and we totally encourage that), but before you do, don’t neglect the easiest stuff that can transform the driving dynamics of any vintage car.
Back in the Dec. ’12 issue, Editor Hunkins wrote an editorial titled “The Low Hanging Fruit,” which pointed out a few of the easy mods that apply to pretty much every car, regardless of make, model, or style. The suggestions revolved around chassis, suspension, and safety mods rather than power, because, well, to be honest most gearheads focus way too much on power numbers first. Horsepower and torque are great things when wielded properly, but you need to have a sound foundation to put them to any practical use beyond bragging rights. Plus, they do nothing for the driving experience of your car. Trust us, these are the 11 easy mods that every vintage car needs. Unless you’ve done these, you have no idea how enjoyable your car can be to drive, and you’re not getting the most out of what you already have.
Stock versus stock, there is simply no comparing the responsiveness of modern muscle to vintage, and there are several good reasons for that, all of which are remediable. Check out the size of the steering wheel in most vintage American cars and you’ll note that it’s markedly larger in diameter than most cars built today. Couple that with the average 17:1 or slower ratio in the steering box and you’ve got one slow responding car that requires a lot of driver input. In most cases, a super simple swap to a quicker-ratio steering box (usually 15:1 or numerically lower) will have a dramatic effect on the car’s response without any degradation of steering travel or geometry. Classic Performance Products (shown), Flaming River, and Borgeson make bolt-in boxes for most popular muscle cars, and many of those boxes will crossover to several other more pedestrian cars. As for that school bus–sized steering wheel, go for a smaller diameter custom wheel for a few bucks extra.
But don’t stop at the box; if there’s a single original part still sullying your steering system, replace it. Outside of suspension, there’s nothing else in your chassis that moves more than your steering linkage and they wear correspondingly. Ball joints, tie-rod ends, drag links, and sometimes even pitman arms are the culprits that contribute to a “looser” feel to the front end and degrade the quality of feedback through the steering wheel. They’re all relatively cheap and easy parts to replace, so when you go for the box swap, take the time to make everything new in the system, and you’ll be rewarded with the most precise steering your car’s engineering can offer. These are available from just about any serious restoration shop, such as YearOne.
You can only go as fast as your brakes will let you. You can get away with drum brakes on the rear for street driving since the majority of stopping power comes from the front of the car, but if you drive your classic car often, you need disc brakes up front. (A top-of-the-line Wilwood six-piston system is shown here, but basic dual-piston kits are available from them for under $700.) We know the old argument, “but people drove these cars for years with drum brakes just fine.” That’s because everyone else had a 300-plus foot 60-0 stopping distance too. Nowadays, even family sedans are in the mid 100-foot zone. Even if you can manage to maintain a decent space between you and the car ahead without someone merging in, if they slam the brakes there’s no way you’ll be able to stop in time to avoid a collision. That’s because that “safe following distance” of about 1 second per 10 mph only accounts for driver reaction time and assumes the two vehicles have roughly the same stopping power. If you’ve got drum brakes (especially manual ones) you have to add several seconds at 60 mph to be in a “safe zone.”
Beyond that, the performance potential is light-years apart. While drums are quickly susceptible to heat and fading with hard or repeated use, disc brakes cool much more quickly no matter the diameter. Perhaps worse than that is the propensity for moments of near complete loss of braking power if you happen to run through a puddle with drum brakes since they cannot evacuate water quickly. In short, unless you’re doing a numbers-matching restoration, just include a disc brake conversion in your hot rodding budget.
One of the most important upgrades on any vintage car is also one of the most neglected: the bushings. We can’t tell you how regularly we see nice looking cars with lots of money in parts thrown at them that are still sporting original bushings somewhere. Write this down: No matter what you do to your car, the results will be compromised if all of your bushings aren’t new, and preferably not rubber. That’s because the handling, steering, braking, and ride quality are all dependent upon the bushings being tight and within spec. Each of those systems is interconnected through bushings in some way, and slop at any point in the chain will result in decreased vehicle dynamics. As a matter of fact, just replacing control arm, sway bar, and body bushing (if your car has them) can make a dramatic improvement in how a car drives with no other new parts. If you’re on a budget, start here.
As far as material, we’re advocates of using Energy Suspension polyurethane bushings (shown) in most suspension systems for street cars, since rubber bushings have a lower durometer to keep NVH levels crotchety-grandpa-pleasingly low. That gain in isolation comes at the cost of feedback and responsiveness that those of us who prefer performance need. The less deflection in the bushings, the more precisely the components can do their jobs; that’s why you’ll see Heim joints and solid bushings in race cars. We wouldn’t recommend the full solid bushing route on a street car since you’ll feel every pebble, but you can safely opt for solid body bushings (such we did with Detroit Speed & Engineering parts on our ’68 Nova) without creating excessive NVH.
Speaking of tires, you can have the best handling car with all the right parts, but it’s all for nothing if your tires aren’t up to the challenge. We’ll go so far as to say the tires are the single most important part of the equation for handling or acceleration. All else can be perfect, but if you can’t translate it to the ground, the car will perform poorly. Even braking is greatly affected by the quality of the tires. Matter of fact, if you’re doing it right, the suspension should be dialed in according to the treadwear of the tire; street tires require different specs than competition tires to get the highest possible traction.
Of course sticky traction does come at the expense of treadwear, and often wet weather traction, but the trade-off can be worthwhile on your weekend play toy. We’re firmly in the 200-treadwear-or-lower camp since it offers the most performance return on investment. If you’re interested in getting involved in the burgeoning autocross community, 200 is the softest compound allowed in many events such as Goodguys autocross, while PHR’s own Muscle Car of the Year (MCOTY) competition allows a tire as sticky as 180. (One of our favorites, the Nitto NT01 shown here, is impressively sticky with a treadwear rating of 100.)
Just like wheels, wider is better with tires when it comes to performance handling or acceleration. The more rubber you can get on the ground under your car, the larger the surface it has to work with and the more aggressively you’ll be able to attack corners or accelerate in a straight line. That extra grip will come at the cost of increased rolling resistance, but we promise you won’t be thinking about that when you’re out enjoying the performance.
The evolution from body-on-frame to unibody-style chassis for cars has had a great impact on the quality of vehicle dynamics and creating better driver's cars since it turned the body of the car into a structural element that the suspension was bolted directly to. It's a derivative of a monocoque-style chassis, which is the basis for F1 racers and many supercars. It's by far a superior way to engineer a vehicle, and also allows easier integration of impact-absorbing crumple zones for safety in collisions.
Unfortunately, there was a long period of time where the unibody technology failed to adequately address the loss of rigidity that occurs without an actual frame tying the front and rear suspension systems of the car together. The result is a flexible chassis that twists in the midzone, compromising performance and control on all fronts. Luckily there is a brutally simple solution: subframe connectors. These connectors tie the front and rear of the chassis together with a wield-in or bolt-in set of steel rails that act as framemembers that substantially reduce chassis twist.
Nearly every popular muscle car, and many classics, have custom options on the market ready to order. (Check out the DSE kit show.) No one makes them for your car? No worries; subframe connectors can be created simply for most cars with standard 2x3 rectangular tube and a little cutting and notching. Pro Tip: Always weld in subframes for the greatest rigidity, and to really get the greatest benefit keep the subframes as straight as possible, cut the floorpans to accomodate them, and weld everything together.
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).
More than just being the cornerstone of style that can make or break your car, the wheels can have a huge influence on how the car performs. On the handling side, wider is always better, since the more wheel width you have, the greater the tire width can be, which puts more rubber on the ground for traction. Diameter is an equally important point of consideration since that will dictate the tire contact patch size and the brake packages you have available. A larger diameter will enable you to fit bigger brakes, which can be beneficial if you plan on putting your car on track, and it will also give you access to the more aggressive tires that have been developed for modern sports and supercars. It’s sad, but true that you’re decidedly limited on options with 15- or even 16-inch wheels. If cost is a prime concern, a 17-inch wheel will give you the most bang for the buck.
Weight is also a consideration, as well as where the weight is placed. The lighter the wheel, the less work your engine has to do get it moving. On the same token, lighter wheels are also easier for your brakes to stop. You’d be surprised how much some custom carved billet wheels can weigh. Where the weight is placed on the wheel is also important as it affects the moment of inertia, which is the resistance to rotational acceleration about an axis. The further away from the center of the wheel the weight moves, the higher the moment of inertia, and the closer to the center, the lower the inertia. This Weld RT-S S74-style wheel (shown) has great looks, exceptional strength for its weight, and is significantly less expensive than comparable custom wheels.
Overdrive transmissions were developed early on in the history of the automobile, and were commonplace add-ons to transmissions by the 1930s and 1940s. For some reason, however, during the height of the muscle car era overdrive transmissions were nowhere to be found. We can only speculate cheap fuel had something to do with it, but there are oh so many more benefits than just drastically increased fuel economy, the foremost of which is decreased engine and driveline wear. The slower the engine spins (without lugging, of course), the less mechanical wear and stress on the bearings, rings and other moving parts, and the less heat that will be generated in the driveline itself. Technically, lower rpm can even help your oil drain intervals spread out a bit. On top of that, the decreased cruising rpm at freeway speeds will create a huge drop in noise, which we guarantee will create a more pleasant cruising experience. You can still have some rowdy loud mufflers, shift into overdrive, and be able to hear your stereo or carry on a conversation.
Variations of the T56 six-speed with its double overdrive have been in vogue for Pro Touring cars the past few years, but those larger, more costly transmissions aren’t the only way to go. We’re still big fans of the lighter, easier-to-package TKO 500 and 600 five-speeds, like this kit shown from American Powertrain. Plus, there are several full auto-to-manual swap kits on the market for most popular muscle cars that are home garage friendly. If you’re staying automatic, it will be even easier and cheaper, since many late-model GM and Ford automatics will bolt right into vintage cars, and there are some conversions available for Mopars as well. Or you can forgo the swap, keep you original trans, and add on an auxiliary overdrive from Gear Vendors. In any event, get yourself another gear!