Kevin's Carbon Fiber Miata Body Project
Kevin's Carbon Adventure
A 1990 Mazda Miata owner's failed DIY attempt at a carbon fiber body
Kevin, the owner of a rust-affected 1990 NA Miata, set out to replace rusted rear quarters and the front fenders/headlights with homemade carbon fiber skins, using bondo and foam shapes molded directly on the car. After months of experimentation with resins and layup techniques, the project was abandoned due to poor cosmetic results and a severe allergic reaction to epoxy resin, with Kevin later turning to vinyl wrap instead.
Parts used
Parts named as used in the original write-up, grouped the way the Parts page groups them. Where one of the shops we index lists the same thing for this car, it is shown underneath with a link to the shop.
Body & Trim 6
- West System 105 epoxy resin with 207 hardener
Used for carbon fiber layups after the original art resin epoxy proved too flexible
- ArtResin epoxy
Leftover woodworking epoxy used for the first carbon fiber test piece, found too flexible for body panels
- Metallic pigment
Mixed into epoxy for a textured metallic green test panel, later found splotchy
- Tyvek tape
Used as a mold release on the car body for carbon layups, worked better than plastic wrap
- Partall mold release wax #2
Ordered as an improved mold release for future carbon fiber parts after plastic wrap and tyvek issues
- Stanley Surform flat mill file tool
Used to shape the foam headlight/fender mold by hogging off or smoothing material
Photos
21 pictures collected from the write-up, in the order they were posted, shown from Kevin's Carbon Adventure. A picture opens larger here, with the way through to the page it is on.
KevinsCarbonAdventure · 2019-12-20T17:32:53-0500 9this post at Kevin's Carbon Adventure ↗
KevinsCarbonAdventure · 2019-12-21T10:56:26-0500 4this post at Kevin's Carbon Adventure ↗
KevinsCarbonAdventure · 2019-12-21T18:01:59-0500 3this post at Kevin's Carbon Adventure ↗
KevinsCarbonAdventure · 2020-03-21T13:10:19-0400 4this post at Kevin's Carbon Adventure ↗
KevinsCarbonAdventure · 2020-04-21T06:50:46-0400 1this post at Kevin's Carbon Adventure ↗
How it was done
Starting condition
The car had 198,000 miles and decent paint overall, but rust was bubbling at the rear quarters and rockers. Cutting into the area revealed the rust was worse than expected, pushing Kevin toward a DIY carbon fiber body rather than conventional repair or widebody flares.
Planning the carbon fiber approach
Kevin planned to mold carbon skins directly over bondo-shaped rear quarters using the car itself as a mold, relying on a mold-lock effect to hold the panels without fasteners. He also planned to delete the pop-up headlights, sculpt new fixed headlight/fender shapes from foam and bondo, and eventually build a carbon hood with a ram air intake.
Material testing
Early tests with leftover art resin epoxy produced flexible, unusable carbon. Switching to West System 105 resin with 207 hardener improved cure time, and a two-layer layup achieved enough stiffness. Kevin also experimented with metallic pigment for a textured look and learned lessons about mold release, tape, and epoxy quantity.
Layup attempts and problems
Kevin laid up a single carbon layer on the passenger rear quarter directly over the prepped bondo surface, encountering wrinkles and release issues from plastic wrap, while tyvek tape worked better. A second supplier's mold release product was ordered for future parts.
Project abandoned
By March 2020 Kevin reported the carbon panels had technically worked but looked poor, with the driver's side panel discoloring underneath. He also developed severe hives from epoxy exposure, requiring steroid treatment, which along with the cosmetic failure led him to abandon the carbon fiber approach, having spent about $300.
Switch to vinyl wrap
Later, Kevin decided to use vinyl wrap instead of paint for budget reasons, successfully wrapping the bootlid and a rear quarter panel, with plans to wrap the rest of the body except the fenders, which would instead get flares for wider wheels.
A summary in our own words. The full account, with all its detail, is in the original write-up: read it at Kevin's Carbon Adventure ↗
Worth knowing
- Don't tape fabric down while laying it up, as pulled strands show in the final piece
- Cut carbon cloth close to final size rather than trimming excess after wetting it out
- Mix more epoxy than seems necessary, as running out mid-layup causes problems
- Use proper mold release such as wax instead of plastic wrap, which can stick and distort the surface
- Wear maximum PPE when working with epoxy resin, since sensitization can cause severe allergic reactions
- A single layer of carbon with basic epoxy is too flexible; multiple layers are needed for rigidity