Developed an underbody clanging sort of rattle from the bottom of the car. It's certainly a sound that something is loose or flailing, also sounds like something is making contact with a metal material. Closest description I can relate it to is a bit like the a paint rattle can when you shake it, that kind of light contact sound but a metal surface making contact with another solid.
It's very loud and only occurs when the suspension is working over an uneven section of road, pothole or when taking a speed bump quite firmly or faster than usual.
I've looked under the car with my maglight before it was dusk and absolutely nothing looks out of place or is hanging down, at least that's obvious. I don't look under there often in truth
First suspicion was an under-tray but none of these are loose after I gave them a knock. I wondered if there was a dropped screw or bit of metal on the front undertray near the splitter (from working in the engine bay), but the sound wasn't similar when I hit the tray in different areas with the torch
The cars sat on AP 20mm lowering springs and has been for 20 months or so. I've never had any clearance or ground issues on the roads I typically use, mainly because it's simply not low enough to encourage that.
Any ideas or where I should start next?
Thanks.