Rocker PanelInstallation
Inner rockers, OE-style rocker panels, and slip-on outer rockers. Heavy-gauge steel, manufactured to match factory contours. Do it once — do it right.
Your rocker is a box, not a single piece of metal. The inner rocker carries the load, the outer rocker closes the box and takes the abuse, and the pinch welds tie it all together. Figure out how far the rust went before you order anything.
The backbone of the rocker box. Replace it when rust has eaten through the inside wall, the floor-to-rocker seam, or the jack points. If the inner is soft, nothing welded to it is going to hold.
Jump to guide →A full-length outer rocker with the wheel-opening arches formed in. It replaces the original outer at the factory seams: the door sill flange, the lips around both wheel openings, and the bottom pinch weld. The right call when the outer skin is rotted through or the arch edges are gone.
Jump to guide →Slides over the original outer rocker. The stepped top flange seats at the door sill, the face covers the outer skin, and the bottom flange laps the pinch weld. A faster repair when rust is in the outer skin and the inner is still solid. It is a repair panel, not a structural fix.
Jump to guide →- 1Support the car properly. Level ground, jack stands under solid frame or subframe points — never under the rocker you're about to remove.
- 2Measure everything. Door gaps at the front, rear, and sill. Diagonals across the door opening. Write them down. These numbers are your target when the new metal goes in.
- 3Brace the door openings. On unibody cars the rocker is structure. Tack an X-brace across each door opening before cutting so the body can't sag or spread.
- 4Disconnect the battery and clear the area. Pull carpet, sill plates, seat belts, and anything near the weld zone. Check for fuel and brake lines running along the rocker.
The inner rocker ties the floor, the pillars, and the frame rails together. Treat this like the structural repair it is — brace it, measure it, and don't rush the fit.
With the car braced and measured, remove the outer rocker to get at the inner — drill the spot welds along the door sill, the wheel-opening lips, and the pinch flange. Now you can see the real damage. Map the rot with a marker and plan your cuts to land on clean, solid steel at the pillars and floor seam.
- Remove the outer rocker first — you'll replace it after
- Probe suspect areas with a screwdriver — soft metal goes
- Check where the floor pan meets the inner rocker
- Keep the old panel for reference on hole and bracket locations
Find every factory spot weld — a flap disc or wire wheel will make them show. Drill them with a spot weld cutter, only through the layer you're removing. Cut the ends at your marked lines and separate the old inner. Prying before every weld is drilled tears the flanges you need to keep.
- Count the spot welds and note the spacing — you'll match it
- Drill only the top layer; keep the mating flange intact
- Grind remaining weld nubs flat before fitting
- Clean all mating flanges to bare metal, then weld-through primer
Our inner rockers are manufactured to match factory contours, but your car has been settling for decades. Test fit, trim where needed, and check it against the measurements you took before cutting. Drill 5/16" plug weld holes in the new panel's flanges to match the factory spot weld pattern, then clamp it down tight.
- Re-check door gaps and diagonals with the panel clamped
- Hang the doors if you need to — gaps don't lie
- Space plug holes like the factory did, usually 1"–1.5"
- Weld-through primer on both mating surfaces
Fill every plug hole, skipping around the panel so heat never builds in one spot. Butt weld the end cuts in short stitches. Grind flush where the outer rocker will sit. Before you close the box, seam seal the floor joint and coat the inside of the cavity — once the outer goes on, this is your last clean shot at it.
- Start the plug weld in the hole, spiral out to the edge
- Skip around — never weld neighbors back to back
- Seam seal the floor-to-rocker joint
- Prime and coat the cavity before installing the outer
This full-length panel replaces the original outer rocker at the factory seams: the flange along the door sill, the lips around both wheel openings, and the bottom pinch weld. Because the arches are formed into the panel, the wheel openings are where you'll spend most of your fitting time.
Hold the new panel against the car and mark where its arches and ends land. Then find every factory spot weld along the door sill flange, around both wheel-opening lips, and down the bottom pinch flange. Drill them out through the outer layer only and pull the old rocker off. If the new panel ends short of a factory seam, mark a clean section cut and make it there.
- A flap disc or wire wheel makes spot welds show
- Count the welds on each flange — you'll match the pattern
- Drill the outer layer only; keep the mating flanges
- Pull it in one piece if you can — it's your reference
Grind the leftover weld nubs flat on the sill flange, the wheel-opening lips, and the pinch flange. Straighten anything you bent with a hammer and dolly — the new panel can only sit as flat as the flanges under it. With the outer off, take a hard look at the inner rocker. Treat surface rust now, because it won't get easier.
- Every mating surface to bright metal
- True up bent flanges before test fitting
- Inner rocker rotted through? Stop and see Part 01
- Weld-through primer on all mating flanges
This is where the job is won. Clamp the panel along the sill and pinch flanges, then look at the wheel openings — the arches formed into the panel should line up with the fender and quarter openings, and the body line should flow straight through. Close the doors and check every gap against what you measured before cutting. Our rocker panels are manufactured to match factory contours — your job is to match them to your car.
- Arch edges flush with the fender and quarter openings
- Door gaps even front to back, door bottom to rocker
- Trim and massage the arch lips until they sit tight
- Drill 5/16" plug holes along every flange once it fits
Tack the corners and the middle, then close the doors and check the gaps one more time. Plug weld along the door sill flange, around both arch lips, and down the pinch flange, skipping around the panel so heat never builds in one spot. If you made a section cut, stitch that seam in short tacks. A long flat rocker skin warps fast — heat control is everything here.
- Ground clamp on the body near the weld, not on the new panel
- Match the factory spot weld spacing
- Compressed air on each weld speeds cooling
- Grind flush and check for pin holes before sealing
Rockers rust from the inside out, so protect both sides. Seam seal the sill flange, the arch lips, and any section seams. Prime the outside and spray cavity wax inside the rocker box through the access holes. Make sure the drain holes are open. Water is going to get in there — your job is to make sure it gets out.
- Seam sealer on every joint, including the arch lips
- Epoxy or etching primer on all bare metal
- Cavity wax inside the rocker box, end to end
- Keep factory drain holes clear — never seal them shut
A slip-on rocker slides over the original outer rocker — stepped top flange at the sill, face over the outer skin, bottom flange lapping the pinch weld. It's a faster, less invasive repair when the damage is in the outer skin and the inner structure is still solid. Done wrong, it hides rust instead of fixing it — so do the prep.
Don't cover cancer. Cut away every section of the original outer rocker that's rusted through, grind off loose scale, and treat what's left with a rust encapsulator. Then check the inner rocker through the openings. If it's soft, a slip-on won't save it — go to Part 01 first.
- Remove all rust-through — the slip-on isn't a patch for holes
- Encapsulator on remaining metal, inside and out
- Inspect the inner rocker before going any further
- Clean the top and bottom weld zones to bare metal
Work the panel up and over the original rocker. The stepped top flange seats up at the door sill, the face lies against the outer skin, and the bottom flange laps under the pinch weld. It won't drop in perfectly — trim the curved ends to meet the wheel openings and dress the flanges until the panel sits tight with no gaps or bulges behind it. Close the doors and check clearance before anything gets welded.
- Top flange seated full length along the sill
- Panel snug to the original — no air gap behind the face
- Trim curved ends to follow the wheel openings
- Clamp the bottom flange to the pinch weld every 8"–10"
Drill 5/16" plug weld holes along the top flange and through the bottom flange where it laps the pinch weld. Weld-through primer goes between the layers before final clamping. Plug weld through the holes into the original rocker, working end to end and skipping around to control heat. Tack the curved ends at the wheel openings.
- Plug holes every 1"–1.5" along the top and bottom flanges
- Weld-through primer between the slip-on and original
- Skip around — that long flat skin will oil-can
- Grind flush and check for pin holes
This is the step that decides whether your slip-on lasts. Any moisture that gets between the two layers sits there and eats both of them. Run a continuous bead of seam sealer along the top flange at the sill, the curved ends at the wheel openings, and the bottom flange at the pinch weld. Prime, then spray cavity wax inside the rocker box through the access holes.
- Continuous bead along the top flange — no gaps
- Seal both curved ends at the wheel openings
- Cavity wax inside the original rocker box
- Keep drain holes in the inner structure open
If both sides of the box need work, the inner goes in first, every time. You can't weld or protect an inner rocker once the outer is closed up over it.
A unibody without its rocker can sag in the middle the moment it's off the stands. Tack in door bars before you cut, and leave them until the last weld is done.
Measure door gaps before you cut and check them again before every round of welding. If the gaps change, something moved — fix it before the panel is locked in.
Count and space your plug welds like the factory spot welds you drilled out. It keeps the repair as strong as original and makes it disappear once it's painted.
Water trapped between a slip-on and the original rocker rusts both from the inside. Encapsulate before install, seal every edge after. No shortcuts on this one.
A can of cavity wax costs less than a tank of gas. Spray every inch inside the rocker box and keep the drain holes clear. It's the difference between 5 years and 25.
Build it once.
Build it right.
Our rocker panels are manufactured to match factory contours from heavy-gauge steel — built for welders who take the work seriously.
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Heavy-gauge replacement panels manufactured to match factory contours. No shortcuts. No cosmetic patches.