How to Install Rear Side Splitters (Rear Spats) – Step-by-Step Guide
Rear side splitters—often called rear spats—mount on the lower corners of the rear bumper. They visually widen the rear end, tie in with side skirts, and complete the aero look. Because they sit low and take constant vibration, the key to a clean install is symmetry, solid mounting, and proper surface prep.
This guide covers the most common mounting methods: 3M VHB tape, hardware (screws/bolts), or a combined install (recommended).
What You’ll Need
Tools
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Microfiber towels
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Isopropyl alcohol (IPA) 70%–99%
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Painter’s tape (masking tape)
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Measuring tape or ruler
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Marker/pencil
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Heat gun or hair dryer (recommended in cold weather)
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Drill + small drill bits (only if using hardware)
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Screwdriver / bit set
Materials
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3M VHB tape (if included/required)
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3M adhesion promoter (highly recommended)
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Included screws/bolts/washers (if your kit uses hardware)
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Optional: medium threadlocker
Step 1: Choose Placement and Match Both Sides
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Hold each rear side splitter in position on the bumper corner.
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Confirm:
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It follows the bumper line naturally
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The angle looks identical on both sides
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It doesn’t interfere with reflectors, parking sensors, or exhaust clearance
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Use painter’s tape to mark reference points:
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Top edge position
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Rear edge position
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A small “corner” mark to help repeat placement
Pro tip: Measure from a fixed bumper feature (reflector edge, body seam, diffuser edge, lower bumper lip) to the splitter edges—then copy the same measurements to the other side.
Step 2: Test Fit (Dry Fit)
Before removing any tape backing:
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Check the part sits flush with minimal gaps.
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If the bumper is heavily curved, a combined tape + hardware install will usually give the best long-term result.
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Step back and verify the look is even left-to-right.
Step 3: Proper Surface Prep (Most Important Step)
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Wash the area and dry completely.
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Wipe the mounting zone with IPA (repeat twice).
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Apply 3M adhesion promoter only where the tape will contact (thin layer).
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Let it flash off per the product instructions.
This prevents lifting corners and improves durability in wet/cold conditions.
Step 4: Tape-Only Installation (If Your Kit Uses 3M VHB)
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If tape is not pre-applied, apply 3M VHB tape to the part and press firmly.
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Peel a small section of liner at each end to create pull tabs.
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Align the splitter using your tape marks.
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Press lightly to set the position.
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Pull the liners out slowly while maintaining pressure.
Press time: Press firmly for 60–90 seconds across the entire part.
Cure time:
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Avoid washing for 24–48 hours
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Full bond strength typically develops over ~72 hours
Step 5: Hardware Installation (Recommended for Long-Term Use)
If your kit includes screws/bolts:
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Align the splitter and mark hole locations.
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Remove the splitter and drill small pilot holes (start small).
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Reposition and install screws loosely at first.
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Tighten evenly until secure—do not overtighten.
Best practice: Use washers to spread load and reduce stress marks.
Step 6: Combined Method (Best Overall)
For the strongest, most reliable install:
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Use 3M VHB tape to keep full surface contact and reduce vibration
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Use hardware to mechanically lock the part in place
This is the best setup for high-speed driving, wet weather, and long-term durability.
Final Checks
Before driving:
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Push-test each splitter (no movement or rattles).
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Verify both sides match visually from behind and from a 45° angle.
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Confirm exhaust clearance and no contact with hot parts.
After 7–14 days:
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Re-check hardware tightness (normal for new installs).
Aftercare Tips
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Avoid pressure washing directly at the edges for the first week.
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In cold weather, warm the bumper surface and the part slightly before bonding.
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If a corner starts lifting, it’s usually due to poor surface prep or installation below recommended temperature.
