Rear brake bias valve clunking when I hit the brake pedal?

[BristolSam16v]

Whilst removing the petrol tank and fitting braided hoses I noticed the rear valve was seized. so I sprayed it with wd 40 and wirebrushed it then added lots of copper grease so it moves freely.

Now everytime I hit the brake it makes a clunking noises

[drsmith1979]

valver, willy 1,2,3?

[MAXIBOY]

i say this again never use wd40 or copper grease on any brakes components as it runs the rubber seals

[BristolSam16v]

Its on a valver and the rubber seal looks ok ran out of red rubber grease when I did the front slide pins :(

Looks like the clunk is coming from the spring assembly bit, can't figure out why though :S