Brake "funny"

Not me, but lifted off our local Facebook page.
I'll pass back any useful comments to them (with due attribution!). Someone suggested CV joint.

Any local mechanics able to advise what this could be?
When the front brakes on my car warm up in use then they randomly start to make a loud thud / clunk sound and you can feel it through the foot pedal.
Only happens when the brakes are warmed up, so no garage can ever find an issue as even on a short test drive it wouldn’t show up, but once it starts it then continues randomly making this loud thud /clunk when you brake (not every time but more often than not) until the car is parked up again for a while.
Seems to occur sooner into a drive and then more frequently on hot sunny days rather than cold wet days. Also occurs more often when driving in urban areas where you are on and off the brakes and also if I have driven down any of the steep hills around here.
Two garages have both seen the brakes. Neither found anything. Both say it is perfectly safe, which maybe true but it is very annoying and is distracting. I would just like to know what is causing it because I am not making it up and I’m not going crazy!
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On 25/04/2018 16:06, newshound wrote:

I would hazard a guess at a faulty servo, if so, then it will still clunk even if the car is stationary.
Another possible is a loose steering or suspension joint, or even a worn shock absorber, they do odd things when they get some play between top and bottom, but it is hard to find as they don't always leak and with the spring on, it is difficult to make the play show up.
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On 25-Apr-18 4:06 PM, newshound wrote:

I'd say a cracked disc that can only be seen by FPI or microscopic inspection. Even in cast iron cracks aren't always open and easy to see.
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On 27/04/2018 08:23, Peter Hill wrote:

Interesting idea. I guess the delta T might open up the crack and/or develop a step.
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On 27/04/2018 08:23, Peter Hill wrote:

Wouldn't on of the pads be subject to accelerated wear?
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On 27-Apr-18 10:32 PM, Fredxx wrote:

Maybe halve the life of the pad, so for a sporty car driven proper 1mm/2000 miles instead of 1mm/4000 miles, for a shopping trolley 1mm/4000miles instead of 1mm/8000 miles. Not measurable unless driven 1,000 of miles. Even then on single sided brakes it could be discounted as sticky piston or pad. And if cracked both sides the pad wear will still be faster but even.
Yes, you get an dirty wheel quite quickly. Very noticeable with alloys but steel it would be hidden by the wheel trim. But again this may get discounted as a "dusty" brand of pad.
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