Your GT3RS is it a 4.0?

 

Nice! No car is an investment. Just own, drive and enjoy. Look forward to watching your modifications.

 

Recently purchased a 2011 V12 Vantage. Rear suspension seems excessively harsh on rough surfaces or expansion joints and makes a metallic rattling noise. AM dealer replaced control arms but the noise persists. Anyone have this issue or know of a solution?

 

Same with my newly purchased V12, I have rattling/clunking from front & rear suspension, Inspected & found front &rear upper control arm bushings slide back & forth, I think that's the noise, I'm planning to replace those with poly bushings, but been told they're not available now, PowerFlex is redesigning the set for Astons. ETA maybe another month or so.
Did aston dealer replaced upper arms or lower arms on your car? So what are they saying now since it didn't fix the problem?

 

They replaced all 4 upper control arm and bushing assemblies ($5700). Told me no further issues. I live 110 miles from the dealer and so driving home heard same noises within a few miles. Went back and they said that some noise may be due to the internal dampening solenoid valves of the struts and is "normal". Seems like BS to me.

 

Is It same exact noise? If it is, I'd go back to them, tell they misdiagnosed it.
I have a V8 Vantage too, I hear little bit of similar noise from that car too, so I'm hoping in my case it's the bushings, because V8 don't have electronic dampers.
And I just replaced those with BC coilovers, still hears the noise mostly when it's cold.

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Try and lube the bushings and see if the noise goes away?
Then you can be sure they are the culprit.