I was experiencing a thunk (no not my forehead on windscreen) when
braking and spent nearly a year looking for the source.
I believe I have found it in a most unlikely place. I was trying to
correlate the occasional thunk and had convinced myself that it was the
braking system. Seems it was caused by the accelerator pedal relay
shaft having worn (nonexistent) bushes.
So the sound was not coming from the brake system, splines, caliper at
all. I think it is coming from what Moss calls the
accelerator relay shaft. They call for two felt bushes on either end
of this rod that hangs from two brackets on the firewall.
I have pulled the manifolds and carbs and am slowly getting enough
access to this area to get the assembly out.
Perhaps those wiser than I and with more experience can point me to the
source of parts and give me a few pointers on this seemingly
simple repair. (Felt bushes??)