brake problem

[arsenal_69r]

lowered my car a while back, and it seems to be whenever parking with full lock, there seems to be a clonking sound and my brake pedal will go straight to the floor. pump it a couple of times and it comes back to life again. any suggestions?
I have recently had it in an Audi specialist and all they could seem to find was a small air block. however it is still happening

 

[sportquattro]

I'd take it back to the specialist (or a better one) and not drive it until its sorted, sounds like a major accident waiting to happen.

 

[arsenal_69r]

Well the brakes are superb since the air has come out just when parking