The beater's interior package tray was literally toast. Nothing left of it. So I decided to throw a new one in. I got the jute padding and put it in last weekend. Really spruced up the interior! (Thanks Todd!) Anyway, now when I'm on the highway, the pressure from the trunk goes up into the headliner and fills it up like a balloon. It literally ripped it off one of the bows. It didn't help that two of the bows weren't clipped in the center either. So today, I carefully took the forward portion of the headliner down and reclipped two of the bows into the center of the roof. The headliner is pretty fragile in this car. I took it around town and it's definitely better- it's not rubbing up against the top of my head now, but I haven't taken it on the highway yet.
The package tray on the olds lifts at highway speeds with the windows down. I call it the speed activated rear spolier....
I'll take a wild stab at this prob, although I've never heard of it. Obviously, it's a pressure problem. Earlier cars like my 67 GS had vented rr quarter drain plugs. Do you have a separator board behind the seat to block off the trunk? Typically, those boards have "knockouts" in different places, there's like 2 big round ones in the middle. The cars I see in boneyards are usually knocked out there. I'm not sure if they fall out or were punched out on assembly. If those are gone, then air can pass from the trunk into the back seat, under the back seat, out the jamb vents...It was all part of the flow thru ventilation when GM removed the vent windows. It's explained in the manual, I think. Maybe the new, tighter tray caused more of a problem. It's a thought. Is it a solid or mesh tray?
You know Frank, that's a great idea! I didn't think of that. Yes, its got a new separator board in it. The tray is mesh but the speaker holes are sealed by the jute backing. So there is no venting at all! Punching out those two holes in the board might just do the trick
Well, maybe check the manual first, Jason. I was just looking at a 14k original 72 Stage on ebay to see what I could see. I know all my cars (not positive about the 70 'vert) those 2 holes I knocked out because that's the way the originals were. Maybe somebody with a lo-mile car or more experience would know. But, I'm pretty sure those holes were to allow air to pass to the cabin to equalize the pressure.
Where did you find a new separator board from? Or did you use your old one as a template and use mdf? My original is pretty tattered...
I like what Frank is saying.. There are (is) air passages in the Trunk boards and rear deck.. Now the quarter panels drains are a also one way valve... Air or water out.. Maybe they are also a Closing of the doors pressure relief type valves..
Is there any holes in the rear wheel wells letting air in to the truck and being force up through the back seat and into the headliner?
Ha! Yeah, the quarters are rotted up to the trunk floor! Took the back seat out after work today and cut out the two round knock out in the divider panel. Definite improvement of the situation. There seems to still be some air getting into the headliner, but it's like 80% better.
