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.