Turned out to be the top nut on both rear shocks were not tight enough. (As ECS and others had suggested). When I went to the powerflex rear shock bushings (see post # 39) I had under torqued the shaft nut because it looked the bushing was getting over compressed. Recently I ditched the flat washers (post # 39) and went back to the OEM curved washers with correct torque. Rattle gone.

 

Great, thanks for the update. Glad you found it.

 

Thank you for your patience on tracking this down. I have an R52 with the same exact noises as yours and I was convinced you had the problem solved with the vapor canister. I'm going to check my top on top of my strut to ensure its properly secured.

 

I've had the exact same noise for way too long! Just had new motor mounts, which were needed anyway, but rattle is exactly the same. Is tightening those nuts something that I can do myself? I just replaced rear pads and rotors myself. My 05 convertible has 133k on it and is so much fun, without the rattle I'll be in heaven. Hope it solves my problem like it did yours. Thanks so much for all your detailed explanations.

 

yes you should be able to drop the shock a bit to tighten it.. rear is not too bad to take off.

 

OP here... Well my rear end noise is back with a vengeance. Only happens over what I would call "sharp" bumps. Doesn't happen over speed bumps, driveway inclines, small pavement patches, etc... Sound is metallic and sort of heavy and hollow sounding and seems to come from right rear. Was convinced it was exhaust but muffler hangers and straps are still good - right side muffler pretty rusted though. Maybe something loose inside rusted right muffler? Fuel tank straps are fine. Thought something might be loose inside rear bumper (because I had to use the tow hook once to get pulled out of gravel) but I took the bumper cover off and the bar is tight. Have never touched the trailing arm bushing or the rear control arms - but they seem fine - car drives well. Rear SB end links is another suspect but the noise isn't consistent with failed links. Replaced original rear links with Lemfoerders less than 15K ago. Sway bar is Hotchkis 19MM. Maybe it's somehow eating end links. I guess step one will be to tighten strut top nuts. Again.

 

OP, I don't know what he did but I drove him around his building and it seemed like he may have known right away what it was. All he told me was that he moved something to give it more clearance and that stopped it right away. I'll try to ask him tomorrow what he did and let you know.
Fred

 

Fred, please update if you were able to find out what was moved.

 

Update: Removed rear struts and tightened top nuts. Both moved a little less than one turn before becoming seated. Also found right side coil spring not seated correctly. Was rotated almost two inches away from stop in upper mount. Compressed spring a little and moved it to the stop. Ride is improved! However, there is still something back there making a heavy metal on metal (plastic on metal) clunk-clunk over harsh bumps. Always a double sound - like something heavy inside a can being shaken. Really sounds like it's coming from the rear bumper bar. I suspect #2 in this pic.

 

I just had my endlinks make noise, it was hard to pinpoint, i thought it was something else.