DIY Wheel-Arch Liner Acoustic Insulation Mod for BYD Atto 3, Seal & Sealion 6 (Drops Coarse-Chip Road Noise by ~2.5 dBA)

[Sealion6_Tourer]

If you drive on coarse-chip bitumen highways in Australia, New Zealand, or the UK, adding closed-cell acoustic foam and butyl deadening mats behind the plastic wheel-arch liners on the BYD Atto 3, Seal, or Sealion 6 is one of the highest-impact weekend DIY upgrades you can do.

Materials Needed (~$95 AUD / £50 total):

• 8 sheets of 2.0mm Butyl Sound Deadener (Car Builders / Dynamat / STP)
• 4 sheets of 6mm Closed-Cell Waterproof Acoustic Liner (CCF) (must be hydrophobic closed-cell so it never holds water!)
• 20 spare 8mm BYD plastic push-clips (in case any brittle clips snap during removal)

Step-by-Step Summary (2 Hours Total):

1. Jack up one corner at a time, remove wheel, and pop out the 11 plastic push-rivets + two 10mm nuts holding the felt/plastic wheel-arch liner.
2. Clean the inner metal guard behind the arch (especially the rear quarter panel towards the cabin bulkhead) with isopropyl alcohol and roller on the 2mm butyl strips.
3. Stick the 6mm waterproof closed-cell foam onto the backside (top side) of the plastic wheel-arch liner.
4. Re-clip the liner. On coarse-chip 100 km/h highways, cabin SPL meter readings drop from 66.8 dBA down to 64.2 dBA!

[nina_b_akl]

Did this exact mod on my Atto 3 using Car Builders Sounddeadener + Waterproof Liner here in Victoria! The front firewall section right behind the front mudflaps is where 70% of the tyre roar enters the footwell.

[Dave_QLD]

@nina_b_akl Emphasising the OP's point: make sure you ONLY use closed-cell polyethylene/neoprene foam inside wheel arches and never open-cell cotton felt, otherwise it acts like a sponge when driving through puddles.

[josh_w_qld]

@Sealion6_Tourer Added the 2mm butyl strips and 6mm waterproof closed-cell foam behind the front wheel-arch liners on Saturday—took about 90 minutes and took the edge right off coarse-chip highway roar!