If you’re building a custom subwoofer box in the bed of your truck, you’ve probably run into a common challenge — how to get bass into the cab without leaving a gaping hole that leaks water, dust, and noise.
The solution? A cab-to-bed pass-through sealed with an accordion boot.
This DIY guide will walk you through how to install one, step by step — giving you a cleaner look, better bass, and weather protection your audio build deserves.
Why Use an Accordion Boot for Audio Blow-Through?
When you cut an opening between the truck cab and bed to allow sound from your subwoofers to pass through, you’re also exposing the cab to:
- Water leaks
- Dust and road grime
- Temperature changes
- Poor air pressure control
- Bass loss due to air escaping
An accordion boot acts as a flexible, weatherproof tunnel that seals that opening while allowing air and sound to flow freely from your speaker box into the cab. It’s a game-changer for blow-through audio setups.
What You’ll Need
What you need to install the accordion boot on your truck.
Step 1: Measure Your Opening
You’ll be cutting a hole through the rear cab wall and the front bed wall. These must match in size and shape.
Measure the width and height of the speaker box port opening
Measure the gap distance between the cab and bed
Use the Boot Opening Calculator to get the correct perimeter size for your boot
Both openings must be identical in size for the boot to fit properly.Step 2: Cut the Cab and Bed Walls
Trace your outline on the rear cab wall and front bed wall
Carefully cut with a jigsaw or reciprocating saw
Deburr and clean the edges so the boot fits snugly
Be sure not to damage any wires or supports behind the cab wall.Step 3: Clean the Mounting Surfaces
Wipe down both mounting areas using rubbing alcohol to remove dirt, oil, or dust. This ensures a secure fit for the boot and any added sealant.
Step 4: Install the Accordion Boot
Start with the cab side and slide the spring steel edge over the window frame or flange
Repeat for the bed side
Press around the entire perimeter to make sure the boot is evenly seated
Use a soft mallet and tap around the opening the help secure the bootStep 5: Join the seam
Trim the section where the metal clip is located is such a way that both ends matchup
In the accordion section with scissors or utility knife create a flap that allows the ends to overlap
To secure the material use super glue to bond the accordion
Installation Guide For SeamStep 6: Test for Fit, Flex, and Sound
Push the bed and cab together gently to compress the boot slightly
Check that there’s no light, air, or water gaps
Do a bass test at low volume and check for flex or air leaks
Tools
- Measuring tape
- Jigsaw or reciprocating saw
- Marker or grease pencil
- Soft Mallet
- Tin Snips or heavy duty scissors
Materials
- Accordion boot (EPDM rubber with spring steel clip)
- Degreaser or rubbing alcohol
- Super Glue
Tips for Better Results
- Paint or seal raw metal edges inside the opening to prevent rust damage
- Leave room for cab and bed movement — the accordion design allows for flex
Where to Get a Quality Accordion Boot
Our boots are made from black EPDM rubber with a built-in spring steel clip — no glue or screws needed for installs.
Shop Accordion Boots Now »
Use the Boot Opening Calculator »
FAQ
Will the accordion boot affect sound quality?
A properly installed boot should not affect the sound quality.
Q: Can the boot handle high SPL levels?
In most cases yes, the accordion boots are made from flexible EPDM rubber with embedded metal clips. They’re designed to flex under pressure without tearing, making them a good choice for both daily drivers and competition-level builds. Keep in mind there can be limits to what any material can handle.
Q: Do I need to use sealant with the boot?The embedded spring metal clip offers a strong grip on most flanges. If properly installed sealants are not necessary. However if you feel you need to seal avoid petroleum based sealants as it could effect the integrity of the rubber.
Final Thoughts
If you’re serious about your cab-to-bed audio blow-through build, don’t settle for an open hole or flimsy foam. An accordion boot offers a tight seal, better pressure response, and long-term durability.
This simple mod not only protects your interior.