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[frostbite]

When I start the car from cold, rest my foot on the brake the pedal is normal then after a few seconds it will drop about an inch while idling, I dont notice it when driving/ stopped at lights.

Is this the movment you have?

[TheBoy]

When I start the car from cold, rest my foot on the brake the pedal is normal then after a few seconds it will drop about an inch while idling, I dont notice it when driving/ stopped at lights.

Is this the movment you have?

That sounds like normal vacuum assistance kicking in.  This appears to be a bit of creep beyond that.

[Doctor Gollum]

Block off the vacuum line and see it still does it

That's to say it could be the vacuum effect working on the worn master cylinder... It will pull on the pedal as they're permanently attached 

[aaronjb]

I'm placing my bets on master cylinder seals and TB is just too much of a weakling to provoke the same problem without servo assistance

(After all, in his Jag he probably has a butler to take care of such things as braking)

[Kevin Wood]

(After all, in his Jag he probably has a butler to take care of such things as braking)

I can see that working..

"Er.. May I suggest, sir, that I apply the brakes?"
"No"
"But, sir, that roundabout is getting bigger"
"Effing BMW tard.. mutter"
"Erm.. Would sir care to release the throttle from the carpet?"
"Take that you panzer-driving retard"
<sound of door opening followed by muffled scream>

[tunnie]

(After all, in his Jag he probably has a butler to take care of such things as braking)

I can see that working..

"Er.. May I suggest, sir, that I apply the brakes?"
"No"
"But, sir, that roundabout is getting bigger"
"Effing BMW tard.. mutter"
"Erm.. Would sir care to release the throttle from the carpet?"
"Take that you panzer-driving retard"
<sound of door opening followed by muffled scream>

 

[cam.in.head]

With the brakes being dual circuit if the master cylinder was worn on only one circuit the pedal would slowly sink as the piston moved in the bore .until it came up to the balance point where it is acting only on the other circuit. Then it would go solid and not sink any more. Same idea as if a front or rear brake circiut gave up due to a leak .the brakes would still work on the other circuit albeit sith a greater pedal travel but they would still work.'switching off' each line using the abs valves is a similar test to clamping the hoses.exept clamping the hoses dismisses any abs valve block leakage if there was any. Unlikely ?