rear brakes binding

[A8 Owner]

they have checked calipers and they dont think its that. As he said he would free them off and say if it happens again i would need new one's. He thinks it is a electric problem. Is there anyway by doing the pass air bag light fix, that could cause a problem.

[PsYcHe]

Could be the handbrake that's the problem,especially if they've yanked it hard doing the MOT. Might not be returning properly to free off the calipers.

[David's8]

Originally Posted by PsYcHe

Could be the handbrake that's the problem,especially if they've yanked it hard doing the MOT. Might not be returning properly to free off the calipers.

I think that thats a good call - it provides the connection between the brakes "suddenly" binding and the car being in the hands of the testers.

[roboblob]

Did they remember to take the handbrake off before they moved off , I seem to remember one of out members doing that at a meet ,boy did the air whiff behind them

[briang9]

[A8 Owner]

5pm update was................... They had it on the ramp, and were about to undo brake bleed nipple. To see, if they did this, will the brake come off or stop on.
If it stops on, there going for piston stuck on both sides.
If it frees them off, there looking at ABS pump, as there saying, that would mean that pump is pumping wrong fluid value to brakes.
Think thats right.
Does that sound right?

[PsYcHe]

Not necessarily, are the D2 not a 4-way ABS system with an independent feed for all 4 wheels, so I'd find it strange that both rears have gone.

I'd pop the calipers off and rewind them to see what happens as I'm struggling to see what could have caused both to go at the same time just at MOT time.

A similar (though reverse) issue is found with the XC90 (like the missus has). As it's a foot operated handbrake with noddy little shoes inside the hub (a daft system, but anyway), if the tester can't generate a decent amount of pressure with their left foot, then it won't pass an MOT.