Finally drove my complete frame-off restored M80 Thursday (GM Fast Burn, 700R trans). Outside the car exhaust noise is moderate and sounds solid.
Excess noise entering the passenger compartment is easily identified from the rear/trunk area because almost every square inch of the interior surface is lined with Dynamat (I know, it’s heavy).
Installing the two missing 6x9 speakers in the rear deck lid will not help much because only the speaker cones divide the trunk and passenger compartment.
I’m an acoustics person. The body metal is thin. My best guess is:
1. All trunk panels resonate
2. Substantial exhaust noise filters through all trunk panels
3. The air space within the trunk resonates when its resonant frequency matches the exhaust and even multiples of it.
Please vote/comment on my proposed solutions:
1. Install two 6x9 rear deck speakers (minimal expected improvement).
2. Damp all interior trunk panels including the lid with currently most-accepted spray-on nose/vibration control. What is best spray-on product for this use?
3. Damp bottom/exterior trunk panel as above.
4. Carpet the trunk...OEM? Aftermarket? Custom? Glue-down seems like a bad solution, but maybe Velcro. Is there carpet material that will form-fit by applying a heat gun?
TIA!
Excess noise entering the passenger compartment is easily identified from the rear/trunk area because almost every square inch of the interior surface is lined with Dynamat (I know, it’s heavy).
Installing the two missing 6x9 speakers in the rear deck lid will not help much because only the speaker cones divide the trunk and passenger compartment.
I’m an acoustics person. The body metal is thin. My best guess is:
1. All trunk panels resonate
2. Substantial exhaust noise filters through all trunk panels
3. The air space within the trunk resonates when its resonant frequency matches the exhaust and even multiples of it.
Please vote/comment on my proposed solutions:
1. Install two 6x9 rear deck speakers (minimal expected improvement).
2. Damp all interior trunk panels including the lid with currently most-accepted spray-on nose/vibration control. What is best spray-on product for this use?
3. Damp bottom/exterior trunk panel as above.
4. Carpet the trunk...OEM? Aftermarket? Custom? Glue-down seems like a bad solution, but maybe Velcro. Is there carpet material that will form-fit by applying a heat gun?
TIA!