AC Cobra Bodywork and Design

Overview of AC Cobra bodywork: originals, continuations, replicas (aluminum, composites, resins)

The originals (AC / Shelby, 1962–1967): British “coachbuilt” DNA

The very first Cobras were born directly from the AC Ace: a tubular steel chassis structure (ladder/tubes) combined with a body made of hand-formed aluminum panels, shaped in the British coachbuilding tradition (English wheel), then fitted and assembled on bucks (wooden forms/jigs).

This point is essential: a period Cobra is not a monocoque shell, but an assembly of individually worked and manually adjusted aluminum panels, which explains the small variations from one car to another.

In very simplified terms:

• Mk I / Mk II (289 “leaf spring”): narrow body, very “muscular AC Ace” look, less flared fenders.

• Mk III (427 “coil spring”): significantly wider fenders, wider track, more aggressive proportions.

On genuine cars, the aluminum is beautiful but “alive”: it can dent, and surface preparation and paintwork are demanding. This is also what gives the unique “grain” and subtle reflections that enthusiasts love on an authentic Cobra.

The “continuations”: new cars, original spirit, modernized manufacturing

The term “continuation” covers several realities, but the idea is the same: to recreate a Cobra “as it was”, brand new, sometimes with a specific chassis numbering and with more modern tolerances and solutions.

Shelby CSX (continuation series, e.g. CSX4000 / CSX6000)

Shelby offers continuation models in which the bodywork can be either fiberglass or hand-formed aluminum, depending on the version and options. The Shelby page for the CSX6000 explicitly mentions both materials (“hand laid fiberglass” and “hand formed aluminum”).

On the market, this is often reflected in the distinction between “aluminum-bodied” and “fiberglass-bodied” CSX cars.

AC Mk IV (Autokraft / AC, 1980s–1990s)

Often considered a legitimate descendant on the AC side: high-quality manufacturing, and many sources describe an aluminum body, combined with a modernized, reinforced tubular chassis and independent suspension.

More modern AC versions (composites / carbon / hybrids)

There are also more recent AC generations that move away from the traditional all-aluminum panel construction. Some versions are announced with composite or even carbon fiber bodies, using a monocoque or one-piece shell approach to reduce weight and increase rigidity. One frequently cited example among AC Owners Club discussions is the CRS, featuring a one-piece carbon monocoque body.

There are also mentions of “aluminum-coated composite” bodies on certain generations (Mk VI in some sources).

👉 Bottom line: in the world of continuations, a car can be visually very close to the original while allowing a choice between aluminum (material authenticity) and fiberglass/composite (practicality, cost, usability), depending on your objective.

Replicas: the wide spectrum of body shells (GRP, resins, aluminum, hybrids)

In the replica world, the bodywork is almost always a composite shell (GRP = Glass Reinforced Plastic), manufactured from molds.

A) Fiberglass / GRP (the standard)

• Process: hand-laid / hand-laminated fiberglass and resin (usually polyester or vinylester depending on the manufacturer), gelcoat finish, then reinforcements (inserts, double skins in high-stress areas such as hinges, mounting points, and edges).

• Advantages: lower cost than coachbuilt aluminum, dimensional stability, generally repairable, no “dents” like aluminum.

• Drawbacks: risk of micro-cracking or crazing if the layup is poor or under stress, a material “look and feel” different from bare aluminum, and shape accuracy depends heavily on the quality of the master and molds.

Documented examples:

• Superformance MKIII: “hand laminated fiberglass body” with reinforcements.

• Backdraft: fiberglass/GRP body with strategic reinforcements and a more “modern” approach in some areas (e.g. steel floors mentioned).

• DAX 427: very clear specification: GRP gelcoat, hand-laid laminate, bonded/positioned inner panels, double-skin hood, doors, and trunk lid.

• Pilgrim: replica using a fiberglass (GRP) body, commonly mentioned in club descriptions and listings.

B) Aluminum (the “ultra material-correct” path)

Some high-end replicas go further, offering aluminum bodywork, often built over bucks and sometimes using very advanced tooling. This is the closest approach to the original spirit in terms of material and the car’s “skin.”

The name most frequently cited here is Kirkham, well known for aluminum-bodied Cobras and often mentioned in connection with aluminum-bodied CSX cars as well.

C) Carbon / advanced composites (rarer in replicas, more common in modern interpretations)

Less visually “authentic” if poorly executed, but highly effective in terms of rigidity, weight, and stability. At this point, the car is closer to a Cobra restomod than to a strictly period-correct replica.

The 5 replicas closest to the original (ranking)

Here, “conformity” means silhouette/proportions, details, and material when possible (aluminum vs GRP).

Note: “conform” does not mean “best to drive”—some cars are deliberately modernized.

1) Kirkham Motorsports – the “material & skin” benchmark (aluminum)

Exceptionally well-crafted aluminum bodywork, frequently cited as extremely close to the originals and often used or associated with aluminum-bodied Cobras in the reference market.

2) ERA Replica Automobiles – outstanding shape fidelity (especially 289/FIA and 427)

ERA is regularly described as highly faithful, with sources explicitly listing very accurate fiberglass bodies, particularly for slabside/289 versions.

3) Superformance MKIII – “dimensionally correct” and very refined

Hand-laminated fiberglass bodywork with a clear stated goal of being “aesthetically and dimensionally correct”; one of the most widely recognized high-end replicas.

4) Unique Motorcars – respected for a very traditional approach

Frequently mentioned in discussions balancing authenticity vs drivability, with a reputation for being very “spot on” overall.

(Note: much feedback is community-based, so best seen as a strong trend rather than absolute fact.)

5) Backdraft Racing – high quality, slightly more modern interpretation

Excellent build quality and finishes, reinforced fiberglass/GRP bodywork, but proportions and details can be more modernized depending on version (stance, options, setup) compared to the top three.

Ranking of bodyworks for Shelby Cobra replicas