Maintaining the springs on a classic car will go a long way in ensuring that the vehicle will continue to provide a smooth and comfortable ride, while at the same time improving handling and stability.

Inspect the spring bushings for any signs of wear or damage. These bushings are designed to keep the springs in place and cushion them from road vibrations.

As they begin to wear out, bushings will increasingly allow for more movement. On rough roads, when turning the wheel, or when hard braking, the driver may feel a shimmy from the front of the vehicle or hear clunking or rattling noises. Drivers may also encounter poor handling or jerky steering.

Make sure the ride height is at factory-specified level. If it's too low, it could indicate worn out spring or faulty suspension.

Ride height was traditionally measured from the rocker panel to the ground, but for modern vehicles, it is usually measured from the point where the tires touch the ground to the topmost point of the fender arch. This is how many car manufacturers measure it.

Listen for any unusual noises coming from the springs, such as creaking or squeaking sounds.

Many factors can contribut to noises that appear to come from a car's suspension. While creeks, groans, squeaks, and rattles are notoriously difficult to diagnose due to the variety of contributing factors including worn out bushings in the car's control arms and mounting points are a common issue that can be relatively easily diagnosed with a visual inspection.

Bushings and mounts serve to isolate undesirable forces such as bumps in the road or motor vibration and are frequently the first to degrade over time, becoming literally the squeaky wheel.

These noises can indicate a problem with the springs or the bushings and should be addressed as soon as possible.

Closely examine the springs for any signs of damage or contortion,.  If a vehicle droops or sags on one side or corner, it’s an almost certain sign that the coil springs are damaged. The drooping or sagging is usually caused by one side of the vehicle being overloaded on a regular basis. The vehicle may also sway more in turns or bounce higher than usual. Damaged or bent spring are a common cause of uneven tire wear.

rust can cause damage to the springs over time, so it's important to regularly inspect the springs for signs of rust. If rust is present, have it removed and treated to prevent further corrosion.

It's important to keep in mind that classic cars may have different types of suspension system than the modern cars, it's always better to consult the manual relating to the specific make and model of your classic car.
Regular inspection and maintenance can help extend the life of your classic car's springs and can avoid costly repairs in the future.