Bruce In Philly

2009 C2S

I've had an annoying clunk in my roof for 75K miles and I finally got around to fixing it.

Symptoms:

1 - Only when roof is closed, not there when roof is cracked or opened.
2 - Sounds like plywood, not a "tinky" rattle
3 - Sharp bumps
4 - You can stop the noise by placing your hand just on the interior panel, or just behind on the interior support beam under the roof liner just behind the panel

Fix:

Increase the pressure between the exterior roof panel and interior panel with thick rubber tape and felt

Instructions:

1- Crack roof
2 - From outside, notice you can place your fingers between the exterior roof and interior panel..... and push down. You will notice the interior panel is spring-loaded to push up to the exterior panel. Notice the panels are separated by three foam, triangular bumpers. I suspect these become a bit crushed over time allowing the rattling.
3 - Cut three two-inch strips of 3M extreme mounting tape, a nice dense rubber tape, and stick to underside of exterior panel above the foam bumpers
4 - Cut three strips of adhesive felt or the fuzzy side of Velcro, and stick over the 3M rubber tape
5 - Done

This does two things: 1) increases the pressure between the panels, and 2) cushions any bumping.

Reason for failure of bumpers:

This is my speculation, but notice that when you open the panel backwards (not crack up), in the very first movement of the panels, the exterior roof panel depresses against the non-moving interior panel. Then the pair slides back into the roof cavity. This depressing action crushes the foam bumpers, and in time, makes them less effective.

It took me forever to figure this out as the sound actually sounded like it was coming from the rear of the car... like from the subwoofer. I actually had removed the subwoofer looking for something loose. I even thought it was a control arm. Here, the sound was right above me but appears to emanate from behind.

See my video below.

Peace
Bruce in Philly

slicky rick

got it. thanks bruce

Sydneysixer

great detective work and problem solving Bruce… there is something really satisfying about fixing a rattle/ knock.

I tried unsuccessfully several times to find a creak in my 997.1 before removing the passenger side B & C pillar trim (+ passenger seat belt mountings) and systematically replacing items to isolate the cause. Applying foam tape around the mounting holes of the C-pillar trim seems to have done the trick. Just glad I discovered this after 15 months of ownership, rather than 75,000 miles.

Ben Z

Has this worked for you Bruce, and does the roof still retract with the same ease/speed with the added pressure between the panels ? I have the same clunk or thwack going over bumps, like railroad tracks for example. Sounds like I've got a sheet of plywood strapped to the roof.

However additionally in my case, the left (driver's) rear of the inner panel has much less spring tension than the right. It was something I did, pushed up on it too hard once and felt something give. But looking inside I've never been able to see anything broken or disconnected. Anyone been in there knows how to sort this out?

Bill in Boston

I have the same issue. I also thought it was a "rear of car" thing. accoustics are weird. A temp fix is to insert small black sponges (or folded up paper napkins or something similar) in each corner of the sunroof between the headliner and panel. You can't see them unless you look up. That said, you have to take them out if you want to use the sunroof (I never do anyway).

Bruce In Philly

Sticking pads to the underside of the metal roof panel, over the triangular foam bumpers worked for me. Problem solved. It does not effect retraction of movement of the roof in any way I can tell.

Regarding your spring issue, you can see this spring on either side..... crack the roof open (up), get out of the car and just look. By putting your fingers between the two roof panels and pushing down, you will see the springs in action... I suspect if the springs were stronger, we would not have this clunking issue.

This is NOT a difficult DIY... It should take a total of 15 minutes to do. You can simply use the fuzzy side of velcro tape that I am sure all of us have stuck in a junk drawer somewhere. I used a thick rubber tape and then velco fuzz over that to make it thicker.... but I am sure just the fuzzy felt stuff will work.

Peace
Bruce in Philly

ChicagoSpeed996

Just did this last night with thick felt pads that go under chair legs. Seems to have worked so far!!!!

carguy999

Just did this but did not seem to be the ticket. Thinking next steps will be to pull everything apart unfortunately.

Bruce In Philly

There is another way.... put your hand up on the cross support member (trailing/rear side of the panel.)... and push. Bend it upwards. This increases the arc.

Peace
Bruce in Philly (now Atlanta)

carguy999

Thanks, car is in for a detail but will give this a shot when I get it back