[Zone5]

Howdy all. I have a new 2021 ZL1 with a headliner that thumps with the window down at speeds above 40 MPH. I searched "headliner" and the threads all mentioned headliners that droop in the front or the back. That's not my issue.

My issue is that the headliner edges are snug and tight, but the center section of the headliner is not attached to the roof. Maybe it's supposed to be like that, I don't know, but I can't drive with the driver's window down above 40 MPH without the headliner banging up against the roof and vibrating, making a thumping sound.

I know there's some aerodynamic (parasitic and induced) drag created by the open window, resulting in high and low pressure areas around the window opening and in the cockpit. And it's quite a bit of force. But the fact that I can push on the headliner and feel the 1/2" or so of dead air above the headliner and below the roof led me to suspect that it may not be adequately attached to the roof. Is that normal? Thanks...

[sengli]

Do you have a sunroof or not? All my Gen6 Camaros have had sunroofs. I always like to drive with the windows open and have not noticed this issue.

[Zone5]

No sunroof. thanks.

[2SS Capt]

Originally Posted by Zone5

Howdy all. I have a new 2021 ZL1 with a headliner that thumps with the window down at speeds above 40 MPH. I searched "headliner" and the threads all mentioned headliners that droop in the front or the back. That's not my issue.

My issue is that the headliner edges are snug and tight, but the center section of the headliner is not attached to the roof. Maybe it's supposed to be like that, I don't know, but I can't drive with the driver's window down above 40 MPH without the headliner banging up against the roof and vibrating, making a thumping sound.

I know there's some aerodynamic (parasitic and induced) drag created by the open window, resulting in high and low pressure areas around the window opening and in the cockpit. And it's quite a bit of force. But the fact that I can push on the headliner and feel the 1/2" or so of dead air above the headliner and below the roof led me to suspect that it may not be adequately attached to the roof. Is that normal? Thanks...

Something is wrong, I drive with my windows open pretty much constantly and never had this issue...

[Fifty_Tampa2]

Originally Posted by Zone5

Howdy all. I have a new 2021 ZL1 with a headliner that thumps with the window down at speeds above 40 MPH. I searched "headliner" and the threads all mentioned headliners that droop in the front or the back. That's not my issue.

My issue is that the headliner edges are snug and tight, but the center section of the headliner is not attached to the roof. Maybe it's supposed to be like that, I don't know, but I can't drive with the driver's window down above 40 MPH without the headliner banging up against the roof and vibrating, making a thumping sound.

I know there's some aerodynamic (parasitic and induced) drag created by the open window, resulting in high and low pressure areas around the window opening and in the cockpit. And it's quite a bit of force. But the fact that I can push on the headliner and feel the 1/2" or so of dead air above the headliner and below the roof led me to suspect that it may not be adequately attached to the roof. Is that normal? Thanks...

Definitely not normal, I don’t have a sunroof and I don’t have this issue. Sounds like something isn’t attached, I’d let the dealership take care of it.

[Scottyz]

Take it to the dealer. I’ve had my car into triple digit speeds with windows down for long periods of time with no problems. Sounds like an assembly problem.

[Jsreo]

Does it happen with both windows down or just the driver’s side.

These cars have buffeting issues with just one windows down, try cracking the passenger side a few mm to see if that helps

[Zone5]

First off, thanks to all posters for their responses. Jsreo, funny you mention that. Headliner flapping/vibration/buffeting absolutely happens with the driver's side window down. When both windows are down, it does seem like the buffeting is much reduced, and primarily what I'm hearing is wind and tire noise with both windows open.

My question... Is the headliner, on an exactly comparable car (same year, same exact headliner), supposed to be completely flush with the ceiling/roof, where every square millimeter of the headliner is effectively glued to the ceiling/roof? Or, is the headliner a solid part that's affixed to the ceiling/roof and fastened on the perimeter, or on supports, and thus would not necessarily be perfectly flush? Gents, I'd like to avoid a trip to the dealership, because in other headliner posts I learned that the repair or replacement of the headliner was pretty involved. I'd worry that the dealership would'nt do a perfect job.

[Scottyz]

The seat belt can also cause noises flapping around. I don’t think I have noticed this on my car but other vehicles I have owned would do it.

[2SS Capt]

Originally Posted by Scottyz

The seat belt can also cause noises flapping around. I don’t think I have noticed this on my car but other vehicles I have owned would do it.

I've experienced that, it is usually at higher speeds (above 70 mph)...

[Idaho2018GTPremium]

I checked my '21 ZL1 without sunroof and in the center there is some play, so that when I push it up it travels maybe 1/4" to 3/8" and hits a firm surface. I would say it seems to be affixed around the perimeter. I've never heard it rattling or making noise.

That said - the slight droop in the middle is probably normal and maybe you're hearing the seat belt rattle around like Scotty said. I've heard the passenger side buckle jiggle around on bouncy or rough surfaces before in my car. I think the buckle hits the plastic door or trim and makes noise on occasion.

[Jeb114]

You paid for the warranty let them fix it most likely they will have a interior shop fix it.

[Zone5]

First off, thanks guys for all of your posts. Idaho2018, thanks for checking your car. I was hoping that what I described was normal, and I believe that it is after reading your post. BTW, I don't think my issue is the seatbelt, but I am beginning to think that the slight space above the headliner is normal, contributing to or resulting in the buffeting and just a function of the headliner/cockpit design.

If anyone feels differently, please jump in, because I'm open to all ideas and I certainly don't have a good handle on the situation yet.

[2SS Capt]

Originally Posted by Zone5

First off, thanks guys for all of your posts. Idaho2018, thanks for checking your car. I was hoping that what I described was normal, and I believe that it is after reading your post. BTW, I don't think my issue is the seatbelt, but I am beginning to think that the slight space above the headliner is normal, contributing to or resulting in the buffeting and just a function of the headliner/cockpit design.

If anyone feels differently, please jump in, because I'm open to all ideas and I certainly don't have a good handle on the situation yet.

If it is flapping enough to make noise it's eventually going to start to work itself looser than it is causing even further flapping which will make more noise and the problem is only going to get worse. I've never heard a thing from my headliner and I would suspect that your's may be looser than normal.