Brake Problem

[ydrogs at gmail.com (Gordy Stedman)]

My 79 MK1 makes a very loud metalic clunk when applying the brakes. Under 
gradual braking and down shifting during braking the noise is not present 
but with the clutch out and not in gear there is a very loud clunk sound 
from the engin bay when the brakes are first applied. Checked brakes and 
drivelines since there were redone recently but all is tight. The car brakes 
fine except for the nasty thump. Typical symptom of a brake servo going bad 
or my master cylinder on the way out? TIA

-- 
Gordy
MK1 x 3