If you wheel it, salt it, or simply daily it, the “tin worm” eventually finds your rockers. The good news: with the right products and a methodical approach, you can stop the spread, rebuild the metal, and make it last.
First, decide what you’re fixing
- Surface rust / scabs: Intact metal with scaly oxidation. Treat, seal, and protect.
- Perforation / soft spots: The steel has pinholes or larger through-rust. You’ll be cutting out the bad and welding in new steel (rocker areas are commonly structural; adhesives are for non-structural skins only).
What you’ll use (Eastwood picks)
- Fast Etch – 19418ZP: Phosphoric acid prep that dissolves light rust and leaves a zinc phosphate conversion layer.
- Internal Frame Coating + 24" Nozzle – 15275Z + 12512: 360° cavity-coating for inside rocker cavities, seams, and boxed sections.
- Rust Encapsulator – 16060Z (or Encapsulator Plus – 54292Z / 54290ZP): Seals sound, prepped rust you can’t fully remove.
- 2K AeroSpray Epoxy Primer – 14149Z (gray) or listing in black 14790Z: High-adhesion, corrosion-fighting foundation before topcoat.
- Brush-On Seam Sealer – 51657ZP: Reseal factory seams & new joints after welding/priming.
- Extreme Chassis Black – 11176ZP (quart) or 11175Z (aerosol): Durable, satin black topcoat for undersides and rockers.
- Chassis Black Primer – 11193Z: If you’re using the Chassis Black system.
- 3/8" Spot Weld Cutter – 19017: To release outer skins at factory welds.
- MIG 180 Welder – 33980: Versatile 120/240V MIG for rocker patches and plug welds.
Tools you’ll also want
- Floor jack & rated jack stands, wheel chocks
- Cutoff wheels/air saw, body saw, shears; flap discs for cleanup
- Cardboard & markers for templates, aviation snips, body hammer/dolly
- Welding magnets, clamps/clecos, copper backing spoon for filling pinholes
- Prep supplies: wax/grease remover, clean rags, masking paper/tape
- Respirator (see safety), welding PPE, eye/ear/hand protection, fire watch gear
Safety (read me first)
- Support the vehicle correctly. Rockers are near lift points—use factory jack points, then place stands on solid substructures.
- Welding: Remove nearby trim & carpet. Keep a spray bottle/extinguisher handy. Assign a “fire watch” for 30+ minutes after welding.
- Coatings: Work in excellent ventilation. 2K aerosols (epoxy/urethane) contain sensitizers; follow the SDS and use appropriate respiratory protection (details in Sources 1–2).
Step-by-Step: Stopping Rust & Rebuilding Rockers
1) Inspect & map the damage
Probe the pinch seam, the rear rocker cap, and the lower B-pillar area. If the metal “crunches,” expect perforation behind the outer skin. Plan for cut-out and patch if you’ve got holes or soft metal.
2) Strip & open up the area
- Remove rocker trim/steps, pull back interior carpet & insulation near the work zone.
- Grind/scuff to clean metal 2–3" around the rust zone so you can see solid steel.
- Drill spot welds along the outer rocker with the Eastwood 19017 cutter and peel back or remove the skin as needed.
3) De-rust & stabilize what stays
- For light rust in seams/corners you can’t fully abrade, flood with Fast Etch 19418ZP until bubbling stops. Rinse/wipe per label and let dry.
- On intact, scaly areas you can’t remove entirely, coat with Rust Encapsulator 16060Z or step up to Rust Encapsulator Plus 54292Z/54290ZP after proper prep.
4) Patch panel fabrication
- Template the cutout with cardboard. Transfer to 18–20ga steel. Match the factory pinch seam silhouette & drain holes. (If you own shrinker/stretcher gear, the Eastwood combo 51088 makes curved lip sections easier.)
- Cut out to solid metal; aim for straight, weld-friendly lines and relief drill the corners to reduce stress.
- Set a near-flush butt joint for outer skins; use lap joints only where factory did—and never where water can pool.
5) Weld-through & install
- Punch 5/16–3/8" holes where you’ll recreate factory spot welds and plug weld the outer skin to the inner structure with your MIG 180 (33980).
- Tack, skip, and cool to limit heat input. Dress welds with a flap disc—just flush, don’t thin the panel.
6) Treat the inside (where rust starts)
- Fog the inner rocker and boxed sections using Internal Frame Coating 15275Z + 12512. Feed the 24" tube through factory drain/bolt holes and pull back slowly while spraying for 360° coverage (see Sources 3–5).
7) Seal the outside from the elements
- Degrease and epoxy prime: Use 2K Epoxy 14149Z (gray) or 2K black (14790Z listing on our Eastwood collection). Epoxy is your corrosion-resistant foundation.
- Brush a continuous bead of Seam Sealer 51657ZP over welded seams and factory overlaps. Tool it smooth; maintain any drain paths.
- Topcoat exposed undersides/rockers with Extreme Chassis Black 11176ZP/11175Z. If you’re using the system primer, hit it first with 11193Z.
8) Final checks & future prevention
- Clear the rocker drains. If you added new metal, recreate factory weep holes.
- After the first salty season, re-fog the rocker interior with Internal Frame Coating via the drain holes.
- Wash the rockers often in winter; mud and salt are rust accelerants.
Copy & Paste Shopping List
- Eastwood Fast Etch (SKU 19418ZP)
- Internal Frame Coating + Hose (SKU 15275Z + 12512)
- Rust Encapsulator Black (SKU 16060Z) • Encapsulator Plus Pint (SKU 54292Z) • Quart (SKU 54290ZP)
- 2K AeroSpray Epoxy Primer Gray (SKU 14149Z) • Black listing 14790Z on our Eastwood collection
- Brush-On Seam Sealer (SKU 51657ZP)
- Extreme Chassis Black Quart (SKU 11176ZP) • Aerosol (SKU 11175Z)
- Chassis Black Primer Aerosol (SKU 11193Z)
- Spot Weld Cutter 3/8" (SKU 19017)
- MIG 180 Welder 120/240V (SKU 33980)
Fitment & Structural Note
On many vehicles the rocker assembly is part of the structural sill. Where structure is involved, weld in replacements following OEM procedures; use panel bonding adhesives only on non-structural outer skins where allowed by the manufacturer.
Safety & PPE Disclaimer
Always wear eye protection, gloves, hearing protection, a welding helmet/jacket when welding, and a properly-rated respirator for coating work. 2K epoxies/urethanes can contain isocyanates—review the SDS and follow the manufacturer’s respiratory guidance. Work in excellent ventilation, keep sparks/flame away from solvents/propellants, and dispose of waste per local regulations. If you’re not confident welding structural sections, consult a qualified body tech.
