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Hollow Trunk Syndrome

Alan Fiandaca

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Apr 9, 2019
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Location
Tucson, AZ
Ok, I have a 1969 Road Runner and of course it has a massive trunk deck. My problem is when I close the trunk it sounds like I'm slamming a 55 gallon drum to the ground. It's like the inner brace and the outer skin are rattling together ( if that makes sense ). I know they used a semi hardening rubber on the hoods to kind of tie the skin to the inner bracing, but can't locate any on the trunk lid. Did Plymouth use anything at all on the trunk decks of these cars? Thanks in advance

Al
 
I've owned 3 B Body MOPARS and your description of the trunk sound is accurate.

We need to get our cars together!
 
Yes they did BUT there would be no visible evidence because, unlike hoods where the underside is a skeleton, the trunk has two FULL shells, an inner and an outer. The caulk or whatever they used would have been dabbed on prior to the two halves being sandwiched together.
I can tell you this, if you put your hand in the middle of either outer side of the lid and lightly push down there should be no noticeable movement or "oilcan" effect. I suspect what you hear is normal.
 
I tell people my car sounds like a tin can because it was acid dipped to reduce weight:D
 
Well if I slam the trunk, I can see some movement. I've thought of pushing a stiff sponge or insulation up into the gap or maybe even a shot of spray foam. Just nice to hear I'm not the only one...lol.
 
I've owned 3 B Body MOPARS and your description of the trunk sound is accurate.

We need to get our cars together!
Well,right now,my trans is out getting rebuilt and going with a new LuK clutch also
 
There was a guy named Matt Delaney in Louisiana that built a silver 68 Charger with a Viper engine. His car was in several magazines. One article highlighted how he took steps to eliminate old car noises like this.
He took the inner and outer stampings apart, added some sort of sound deadening in between and welded them back together.
 
I drilled four 1/16 " holes and injected some expanding foam in mine, now it shuts solid and doesn't rattle down the road
 
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Is this a Plymouth thing. Dodge has a pleasing sound. Or different taste in sounds.
 
On the car, are the plastic caps with the drain hole that go in to the almost round holes on the lower trunk extensions, behind the rear wheel well, in place? I noticed that when without the cars sound like an empty drum, with they sound more substantial. Probably slows the amount of air leaving the trunk as it is shut (my lame theory).
 
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