How to Install a Rear Splitter (Step-by-Step Guide)
A rear splitter (often called a rear lip or rear apron) is a clean way to sharpen the rear bumper and complete the full aero look—especially when paired with a front splitter and side skirts. Because it sits low and is exposed to road vibration, water, and debris, a proper installation comes down to three things: surface prep, accurate alignment, and secure fastening.
This guide covers the most common mounting methods: hardware (screws/bolts/clips) with optional 3M VHB tape support.
What You’ll Need
Tools
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Jack + jack stands or ramps (recommended)
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Wheel chocks
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Socket set / ratchet or screwdrivers (depending on hardware)
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Torx bits (common on many EU cars)
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Drill + drill bits (if drilling is required)
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Measuring tape + marker
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Painter’s tape
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Trim removal tool (optional)
Materials
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Included hardware (screws/bolts/washers/clips/brackets)
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Optional: medium-strength threadlocker
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Optional: 3M VHB tape + 3M adhesion promoter (if your kit uses tape)
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Isopropyl alcohol (IPA) + microfiber towels
Safety First
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Park on a flat surface and engage the parking brake.
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Use wheel chocks.
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Lift the rear of the car using proper jacking points and secure it on jack stands (or use ramps).
Step 1: Test Fit and Mark the Center
Before installing:
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Hold the rear splitter against the lower rear bumper.
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Confirm:
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It is centered left-to-right
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The side ends sit evenly and follow the bumper shape
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No contact with the exhaust tips (if applicable)
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Mark reference points with painter’s tape:
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A center mark on the bumper
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A left and right position mark
Pro tip: Measure from a fixed point (bumper corner, reflector edge, etc.) to each end of the splitter to confirm symmetry.
Step 2: Clean the Mounting Surface
Clean the bumper area where the splitter will sit using IPA.
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If tape will be used:
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Clean again.
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Apply 3M adhesion promoter only where tape will contact.
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Let it flash off for a few minutes.
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Step 3: Start Mounting (Loose Fit First)
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Position the splitter using your reference marks.
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Install the center fasteners first and keep them slightly loose.
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Add hardware moving outward toward both sides.
Loose fitting allows final adjustment before tightening.
Step 4: If Drilling Is Required
Many rear splitters use new mounting points under the bumper.
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With the splitter aligned, mark drill points through the mounting holes.
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Remove the splitter.
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Drill pilot holes carefully (start small, then size up if needed).
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Deburr lightly to keep the surface flat.
Important: Check behind the drilling area for exhaust hangers, sensors, wiring, or undertray parts. Do not drill blindly.
Step 5: Tighten in the Correct Order
Once fitment is perfect, tighten in this sequence:
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Center mounting points
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Middle points
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Outer corners last
This reduces twisting and keeps the splitter line straight.
Optional: Add medium threadlocker to bolts that can loosen over time due to vibration.
Step 6: If Your Rear Splitter Uses 3M Tape (Optional)
If tape is included:
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Peel a small section of liner at each end and create pull tabs.
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Position the splitter precisely using your marks.
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Pull the liners out slowly while pressing the splitter into place.
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Press firmly along taped areas for 60–90 seconds.
Cure time: Avoid washing the car for 24–48 hours. Full bond strength typically develops over ~72 hours.
Final Checks (Before Driving)
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Confirm every fastener is installed and tight.
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Shake test: the splitter should not move or rattle.
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Verify exhaust clearance and that nothing touches hot parts.
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Lower the car and inspect alignment from a distance (rear view + side angles).
After the first drive, do a quick re-check—new installs can settle slightly.
Aftercare Tips
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Avoid pressure washing directly at the edges for the first week.
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Re-check fasteners after 7–14 days.
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If the splitter gets scraped, inspect mounting points immediately to prevent cracking or stress damage.
