After releasing the brake pedal - when breaking properly - it sounds as if the rear discs are locked for 1 second before they are released. There is a "clunk" sound from the rear approximately 1 second after breaking, and we also can notice that it has a physical effect on the driveline. It is as if the rear brakes hangs a bit, or if the rear breaks do not release at the same time as the front breaks.

I've had the wheels off and checked the rear callipers, both work fine. I can easily turn the hub after releasing the handbrake, while lifted, so the calipers are not sticky. I've also measured the temperature on all 4 wheels after a long drive, no difference between the front and rear.

I've had the car recently to an indy to check this, but they only changed the diff oil.. Didn't help.

Could it be one of the rear bushings that need to be replaced? Or something with the driveline?

I had a similar problem that’s sounds abit like yours, it felt like a sticky calliper and loads of people helped me out but I was getting a knocking noise. Turned out that lower front suspension arms had gone..(I was driving it for a long time) not saying that is the fault with the car but worth a check or check the rear wishbone might help

Thanks William, it might still be the rear callipers that's sticking only when brake pedal is pushed properly. I will try to replace the rear callipers, but if it's still knocking after that, I need to get the suspension checked again.