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How to Modify an Accordion Boot for Flat Surface Mounting (Step-by-Step Guide)

How to Modify an Accordion Boot for Flat Surface Mounting (Step-by-Step Guide)

When installing an accordion boot, most designs rely on an embedded metal clip to grip a flange around the mounting opening. However, some vehicles or camper shells have a flat surface with no flange, making the factory clip unsuitable. This guide explains how to modify the original accordion boot by removing the embedded metal clip, replacing it with a flat vinyl insert, and securing it with an aluminum retainer. The result is a secure, weather-tight installation on flat surfaces. Note: Any modifications to the original boot will void the manufacturer’s warranty and return policy.

Step-by-Step Instructions

Time Needed : 2 hours 00 minutes

This how-to shows how to remove the factory embedded metal clip from an accordion boot, replace it with a flat vinyl insert, and fasten the boot to a flat surface using an aluminum retainer with self-drilling screws (or pop rivets). The result is a secure, weather-tight installation when no flange is present around the opening.

Before proceeding, the width of the mounting surface must be at minimum 1.5″ wide. If it is smaller than this measurement the boot will fit securely.

  1. Identify the embedded metal clip

    End View of accordion boot show where the metal clip is locatedEnd view of the boot—note the factory metal clip in the channel.

  2. Begin removing the clip

    Using a flat head screwdriver to lift out the rubber holds the metal clip in placeUse a flathead screwdriver to gently separate rubber from the clip to expose it.

  3. Pull the clip out completely

    Show the metal clip being removed from the rubber.Work along the length as the clip becomes accessible. Continue pulling the clip out evenly to avoid tearing the rubber. Completely remove the metal clip

  4. Verify the channel is clear

    End view of the accordion boot showing that the metal clip has been removedEnd view shows an empty channel ready for the vinyl insert.

  5. Prepare the vinyl insert

    Side by side showing the accordion boot without metal clip next to the vinyl stiffing insert to be installCut vinyl insert to the same length as the boot side you’re mounting.

  6. Install the vinyl insert into the channel

    Shows the vinyl insert partial installed on the accordion bootPress the vinyl strip evenly into the channel; avoid twisting.

  7. Inspect the fit

    Vinyl insert completely installed in the rubber channelMake sure the insert is completely mount in the rubber channel to insure a flush, continuous fit.

  8. Tack the insert with adhesive (optional but helpful)

    Using cyanoacrylate to help hold the insert in place during installationApply small drops of cyanoacrylate along the insert to keep it from shifting during install.

  9. End view of the installed insert in the boot

    Inspecting the installation of the vinyl insert end viewInspect the to make sure the insert is fully mounted by look at the end of the boot

  10. Prepare the aluminum retainer

    Aluminum flat bar to be used as a retainerUse 1/16″ × 3/4″ aluminum flat stock cut to length.

  11. Mark 1/8″ holes on aluminum flat bar

    Measuring out the holes in the aluminum flat barLay out holes for even clamping pressure. start 1/2″ from end mark every 3″

  12. Drill the aluminum retainer

    Drilling holes in the aluminum flat barDrill straight holes where marked and deburr edges if needed.

  13. Apply polyurethane sealant to the mounting surface

    Laying a bead of black polyurethane to help create a weather tight seal between the mounting surface and the boot.Lay a continuous bead to create a weather-tight seal.

  14. Position the boot over the sealant

    Placing the boot onto the flat surface over the bead of polyurethaneSet the boot in place; avoid smearing the bead.

  15. Align retainer over the larger side of the boot rubber and drill pilot holes

    Placing the aluminum retailer over the robber boot and drilling pilot holes for to accommodate the screws or pop rivetsDrill pilots through the retainer and into the mounting surface.

  16. Fasten with self-drilling screws (or rivets)

    Using a Philips head screwdriver install screws to mechanically attach the boot to the flat mounting surfaceRecommended: #8 × 5/8″ pan head Phillips self-drilling screws. Install screws at each hole for uniform clamping

  17. Joining multiple retainer sections

    This show a sample where the ends of the aluminum flat bar met in a butt jointButt joints between retainer pieces—keep gaps minimal and screws close to the joint.

  18. Inspect the final fit

    Close up view of the accordion boot installed on a flat surface with the vinyl insert replacing the metal clip held together with an aluminum flat bar retainer with screws.End view: consistent compression against the surface and sealant.

Tools
  • Drill Motor
  • Flathead Screwdriver
  • Phillips Screwdriver
  • Measuring tape or ruler; marker
  • 1/8″ drill (for aluminum retainer holes)
Materials

Notes & Tips

  • Mounting Surface: The width of the mounting surface must a minimum of 1-1/2″ wide
  • Vinyl Insert: Keep it straight and fully seated; small tacks of cyanoacrylate help prevent movement during mounting.
  • Sealant: Use polyurethane for flexibility and adhesion to painted metal/fiberglass/wood. Tool any squeeze-out for a clean edge.
  • Fasteners: For thin sheet metal, self-drilling screws work well. For aluminum skins or where backside access is limited, pop rivets are an alternative.
  • Spacing: 1/8″ holes starting 1/2″ from the end, then every 3″ provides uniform clamping of the boot.

Result: A flange-style accordion boot adapted for a flat mounting surface with a durable, weather-tight seal.

Disclaimer

Questions and Answers

Why replace the embedded metal clip with a vinyl insert?

The clip is for flange mounting. The vinyl insert stabilizes the boot channel so it can be clamped evenly to a flat surface with an aluminum retainer.

What size aluminum retainer works best?

1/16″ × 3/4″ balances stiffness and conformity; thicker stock is harder to form on tight radii.

Ideal fastener spacing?

Start 1/2″ from ends, then a minimum of 3″ for uniform clamping and minimal gaps. If you want you can drill holes closer than the minimum.

Screws or pop rivets?

Self-drilling screws are removable for service and will work best with thicker mounting surfaces. Pop rivets are good a more permanent installation and work best on thinner mounting surface like sheet metal. Choose correct rivet grip for substrate thickness.

Which sealant should I use?

Polyurethane sealant—it adheres well to painted metal, aluminum, fiberglass, and wood, and remains flexible.

Do I need adhesive on the insert?

Optional. Small dabs of cyanoacrylate help prevent insert movement during handling.

Disclaimer & Safety Notice

The information in this article is provided for educational purposes only. Vehicle modifications involve risk. Proceed at your own discretion and assume all responsibility for results, including any damage, injury, or loss that may occur.

No Professional Advice: This content is not engineering, mechanical, or legal advice. If you are unsure about any step, consult a qualified fabricator, body technician, or RV upfitter.

Warranty & Returns: Modifying products or using them outside their standard installation (including trimming, altering embedded clips, bonding to non-flange surfaces, or fabricating custom flanges) may void any manufacturer or store warranty and void return eligibility.

Fitment & Compatibility: Verify measurements, flange thickness, and material compatibility (adhesives/sealants with EPDM, FRP, aluminum, etc.) before cutting or bonding. Perform a test fit on scrap material to confirm the boot’s spring clip engages securely.

Structural & Safety Systems: Cutting body panels can affect structure and safety systems. Confirm that your opening and fastener layout do not interfere with airbags, seatbelts, wiring harnesses, VIN/emissions labels, or load-bearing members.

Adhesives & Sealants: Follow manufacturer instructions, surface prep, and cure times. Use appropriate PPE and ventilation. Check for chemical compatibility and temperature ratings for your climate.

Weatherproofing: Water intrusion can cause corrosion, mold, and electrical issues. Inspect fasteners and seals periodically and re-seal as needed, especially after extreme temperatures, snow/ice, or off-road use.

Tools & PPE: Cutting FRP/metals creates dust and sharp edges. Use eye/hand/respiratory protection, clamp workpieces, and follow safe tool practices.

Regulatory Compliance: Check local/state regulations, insurance requirements, and vehicle inspection rules before performing modifications that alter the cab/cargo barrier or body panels.

Affiliate/Commercial Disclosure (Optional): This post may reference products sold by our company or include affiliate links. We may earn revenue from purchases, at no additional cost to you.

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