Crashy clanky flappy noise at 80+mph

Hello folks.

I have a clanky flappy sort of hard to describe noise above 80mph, but at random intervals… It sounds like the undertray isnt bolted down and is flapping a high speed. But everything is bolted down ok. Thought it might be handbrake cable split banging on tray, so i packed it and it still does it. Wondered if anyone else gets this. Its not engine, im sure of it, its not suspension as it does it on random surfaces, including marble smooth. I’m still caning the tits off it and its all super except for the random noise.

Any thoughts would be appreciated.

Hi Andy - just saying hello and glad to hear you aredriving it like you nicked it

No idea what it is but certainly sounds like air flow/pressure thats causing the problem when you get up to speed. Looks like a good session of poking prodding and general tightening?

PS 80mph - I hope it was not on the public highway!

PPS see the thread below. Fancy a ride to Croft on the 3rd? I think Sean said its a cozzy owners club day so there should be a few nice motors to look at and watch Sean kick their asses on the twisties??
Clickety Click Click

Number plate at the front ?

Check fit of engine cover ?

cat vibrating on rear diffuser ?

No cat, unless I’ve run over one and it’s trying to get out.