My 2008 type s ( Brembos) makes a rattling noise on the drivers front when turning left and Braking. Id does not make it braking right or straight. it does not make it when turning left with out brakes. It sounds like a heat shield rattling. The dust shields on the fronts are long gone (rusted out and removed).
I've removed the front wheel and don't see anything evident.
Short videos attached.
Ideas?

 

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Well, if the #12 left splash guard is gone, then all that remains is the caliper and the inner & outer brake pads to evaluate for potential 'scrapping' on the rotor?
How old and / or how many miles are on the current front brake set?:

 

Brake pads are new but it doesn't rule them out. But I would be inclined to think that it would happen all the time rather then only when turning left wile applying the brake.
Im thinking something has to be moving when side force is applied. Wheel bearing maybe.
Nice diagram BTW.

 

It could be, perhaps one (two piston) inner/outer side of the left brembo caliper has seized or is limited in travel?
Good Luck