Automobile restoration is the process of repairing the degraded aspect of an automobile to return it to an overall “authentic” condition. Restorations should be historically accurate as a representative example of the production model. For example, the guidelines of the Antique Automobile Club of America (AACA) are to “evaluate an antique vehicle, which has been restored to the same state as the dealer could have prepared the vehicle for delivery to the customer.”

In contrast to preserving its historical artifacts through restoration or to conserve significant vehicles by keeping original surfaces and materials, some owners make changes or add modern upgrades during the restoration of their cars that may reduce or enhance the value of the vehicle. In the U.S. a non-original restored car may be termed a “restomod.”

Restoration is sometimes confused with the term “restomod.” A restomod has portions of the car as they were when the car was first offered for sale as well as significant changes (updates). If any part of the car is updated, the car has been “restomodded,” and not restored, such as “a nearly stock-appearing vehicle that has been fitted with late-model chassis, drivetrain, and conveniences.” An “original restoration” puts a car in the same condition as when it was first offered for sale.

Another process is the re-creation, “a vehicle that has been modified to appear like another car or truck entirely, or like a more desirable version of that same vehicle.” Examples include taking a popular model and restoring it to a more desirable, but counterfeit, limited production or muscle car version. High demand for some special automobiles has also led to sophisticated fake replica versions.

Process

A complete restoration includes not only repair of the parts that can be seen – the body, trim, chrome, wheels, and the passenger compartment – but also the components that are not necessarily visible or otherwise evident, including the engine and engine compartment, trunk, frame, driveline, and all ancillary parts like the brakes, accessories, engine cooling system, electrical system, etc.Repairs are made to correct obvious problems, as well as for cosmetic reasons. For example, even if a wheel is covered by a full hubcap and not seen, and is structurally sound, it should have the tire unmounted and any required repairs performed such as rust removal, straightening, priming, and painting.

Disassembly

A complete auto restoration could include total removal of the body, engine, driveline components and related parts from the car, total disassembly, cleaning and repairing of each of the major parts and its components, replacing broken, damaged or worn parts and complete re-assembly and testing. As part of the restoration, each part must be thoroughly examined, cleaned and repaired, or if repair of the individual part would be too costly, replaced (assuming correct, quality parts are available) as necessary to return the entire automobile to “as first sold” condition.

All of the parts showing wear or damage that were originally painted are typically stripped of old paint, with any rust or rust related damage repaired, dents and ripples removed and then the metal refinished, primed and painted with colors to match the original factory colors. Wooden parts should go through the same meticulous inspection and repair process with reglueing, replacement of rotted or termite-damaged wood, sealing and refinishing to match the factory specifications. Pressure treatment with preservative may be considered to safeguard against future wood rot. Chrome and trim may require stripping and repair/refinishing. Fasteners with tool marks, damaged threads, or corrosion need re-plating or replacement-unless the car was originally sold that way. The frame must be thoroughly cleaned and repaired if necessary. Often abrasive blasting of the frame is the most expeditious method of cleaning, but it may still leave microscopic rust pitting behind, so should be followed up with a phosphoric acid ‘rust killer’ solution, before priming. Abrasive blasting using less abrasive soda or crushed walnut shells is less likely than sandblasting to cause damage to fragile items, while still removing corrosion. Acid tank dipping of the frame and or body followed by an E-coat primer after repairs is recognised as the most effective but also most expensive way to get rid of rust and to protect against future corrosion. The chassis frame should be properly coated for rust protection to at least match the standard of the original, to the highest modern standard would safeguard the time and money invested in the restoration.

Interior

The interior of the vehicle should be examined and repaired or replaced to match those that were available from the factory. The seats must be repaired before being re-upholstered and the coil springs repaired, replaced, or retied. The instrument panel, or dashboard contains a number of gauges, each of which have to be inspected and cleaned, repaired, or replaced to be brought back to both operational and cosmetic standards of the car when it was first sold.

Developments in technology have made it possible to salvage the original automobile’s interior by various restoration processes. Examples of this include leather seat, dash, console, steering wheel, door panel, and trim repair, as well as re-dyeing.

Exterior

In a complete restoration, the repair and refinishing of the car’s body and frame must again go through the careful inspection and subsequent repair, and recoating as necessary to bring the car to as first sold condition.

As part of the automotive restoration process, repair of the car’s frame is important since in serves as the foundation for the entire car. The frame should be inspected for straightness, twisting, alignment, rust damage, stress fractures, collision damage and condition of the mounting points for the body, suspension, and other components. Any problems must be repaired, which can be a costly process. For many popular cars, replacement frames can be purchased from parts suppliers specializing in that make of vehicle. This is often a better option than investing money into a severely damaged frame. Depending on the frame construction, mud and water can make their way inside the frame and cause rusting from the inside out, so it can be seriously weakened with little or no external sign. This, and the fact that many replacement chassis/frames are galvanized, provides sound additional reasons to consider a replacement frame.

The re-installation of the repaired or renewed panels requires that the panels be trial fitted and aligned, to check their fit, that their shape ‘flows’ and the gaps between panels are correct. Consistent gaps are very important to a quality finish. Gapping gauges are available for this. The doors, hood, and trunk should open and close properly, and there should be no interference or rubbing. Steel or aluminium door skins and wing/fender edges can generally be adjusted with a hammer and dolly, in extreme cases a pulsed MIG weld bead on a panel edge, that is shaped with a grinder and file, can be good solution. At one time it was common practice to use lead loading to achieve tight panel gaps, especially in the coach building business, but also on the production line. Lead loading is highly skilled, and requires safety precautions because ingested lead or fumes are toxic. The panels have to ‘look right’ together. This is a process of repeated adjustment, because the adjustment of one panel often affects the apparent fit of another. If there are multiple styling lines on the side of a car, it is generally best to align doors on the most prominent one. When the panels on the car are satisfactory, they should be primed and painted a correct historical color for the vehicle if the restoration is striving for historical accuracy. An owner might want to have the car painted to look like a particular specialty vehicle such as a police car, or a delivery van painted to look like it would have in grandfather’s company colors, etc. Individual painting of the panels is generally the correct approach, as this will result in all parts of the panel being painted as opposed to partially re-assembling and then painting, leaving parts of the assembly that are touching or “blind” unpainted. It is useful to mark in some way, if possible, where the panels fit before removal for painting, to aid re-fitting. The separate painting approach should also result in no over-spray on other parts of the since they will not be on the car at that point. It is important when re-assembling painted panels to be aware that the paint is at its thinnest, and most easily damaged on corners, edges, and raised styling lines, and to take extra care with them, such as temporarily taping with masking tape. This is also important when using ultra fine wet flatting paper before polishing, (or when using an electric polishing mop) for the best mirror like finish.

Colors and treatments applied to the panels from the factory should be considered. Although more original looking, period enamel or cellulose paint will be less capable of protecting the car bodywork than modern paints. A car’s owner may wish to have a panel or portion of the car entirely painted when in fact it may have come from the factory with undercoating or other coating applied to one side, which may be less attractive than a smoothly finished and painted panel. In other cases, the owner might paint or plate a collection of small parts to look similar for a better appearance, when the factory might have installed these as many different colors, since the factory’s prime concern was a balance between function and cost and not the appearance of unseen areas. Given the cost of restoration it makes sense to many owners to upgrade the corrosion protection of paints, underseals and anti-rust waxes to far above the original factory standard to protect the time and money invested in the restoration. Some owner’s feel these improvements would make the car a “Restomod”, and not a restoration. The term “Restomod” is not used in the UK.

Mechanical

The entire engine and all related systems are inspected and what ever is necessary to get them into original presale condition is done. The engine and all of the ancillary components – starter, generator/alternator, radiator, distributor, carburetor and all others – must be inspected and corrected to factory specifications. The engine itself, plus the transmission, clutch, overdrive unit, and even the driveshaft must be meticulously inspected, cleaned, and measured for wear. This will show up as deviation from original factory specifications. All of the parts – block, crankcase, head, transmission housing, etc. – should be inspected for cracks or other damage. All moving parts – pistons, crankshaft, camshaft, oil pump, bearing and bushings, flywheel, water pump and all others – must be cleaned and measured against factory specifications and, if necessary, machined or re-manufactured to bring them within specifications. The same goes for the transmission, clutch, differential and all other moving parts of the power line and drive line. All of the electrical system has to be inspected and, if it shows chafing, wear or damage, replaced. If the car is old enough to have used rubber or even fabric based electrical wiring insulation, this should be replaced even if looks okay and upgraded to modern insulation because it is a fire risk. Then the entire engine/driveline will have to be reassembled, replacing all worn bearing and bushings, seals, gaskets, belts and gears.

Reassembly

Finally, the engine/driveline has to be re-installed in the frame, the brakes, wheels and other parts re-installed, the body fitted to the frame and the entire car rechecked and tested.

Restoration of a car is a daunting task, not one to be undertaken lightly, or by the inexperienced. A full restoration can take many years and can cost tens of thousands of dollars; often, and generally, well in excess of what the finished value of the car will be. Many jobs will have to be farmed out to specialty shops; those with the special knowledge and equipment to do the job. Often a restoration once started is left unfinished and the car and parts can be purchased for a fraction of their worth. However, if a person buys an unfinished project, it is imperative to be sure that all of the parts are there. Finding parts for an orphan or rare car can sometimes be impossible. This necessitates the fabrication of parts from scratch, generally at great effort and expense.

Only when a car is completely placed back into the condition it was first sold in is it considered to be restored. Various aspects of a car may be repaired without the car being restored. A car that does not run can be repaired to running condition, but that simply means it will now run and does not mean that any part of the car has been restored. Automotive Restoration means that the car was put back into the condition it was first sold as. Anything else is either repair or restomod. Between these two extremes are the vast bulk of cars that are seen as drivers, neighborhood show cars, and 20-footers – in that they look great from 20 feet (6 m) away. Many value guides offer six levels of quality, from a “parts-only” car to the best at “Number 1” – absolutely perfect in every way.

Upgrades

In the U.S. a non-original restored car may be termed a “restomod.” Upgrades may include newer safety components such as seat belts, brakes or using relays to reduce electric current flowing through light switches. Usability upgrades such as fitting intermittent wipers, an alternator instead of a dynamo, or electronic ignition system instead of contact breaker points ignition system. Emissions upgrades such as hardened valve seats to use standard unleaded fuel, or retrofitted catalytic converters. Upgrades that are easily reversible to the original condition, or were available when the vehicle was current, would be less likely to be controversial. Less acceptable to the classic car market may be major alterations like engine swaps or gearbox transplants, which would be more like hot rodding.

Depending upon how appropriate the upgrades are considered by other owners of the same model, this may reduce or enhance the value of the car. If the car is in regular use non-original upgrades would be likely to be more acceptable, than if the car is a stored collector’s piece where originality would be more important. It is important as a restorer or owner, to know what is acceptable to the potential market for the finished car, in order not to de-value it.