Having been on the drive for 2 weeks in my absence the drive to work this morning was interrupted by a knocking under braking. All was well before, so i can only assume that the weather has had an effect. What do we think ceased caliper?

Simon

 

Does it happen under rough surfaces etc does it sound like its coming from under the wheels?

Have you fitted lowering springs recently?

 

No the S is as standard, and it occurs under all braking conditions. It sounds like it is coming from the offside rear.

 

ABS?

 

Could well be a faulty ABS sensor causing the brake to modulate on one wheel.
You would feel it in the pedal though I'm sure.
Any ABS warning lamps? Does it come on and then go out with ignition and startup?

May be corrosion on the rears if sat with the handbrake on but ought to have scrubbed clean by now.

Did you park up with the handbrake following a particulary mad thrash?

 

Its always a mad trash, so possibly. I will check on the lights, but nothing is lit up when driving along, not sure about the feel of the pedal, but I will pay more attention on the way home.

 

Just thinking about a small warp in the disk thats all.
You would have needed it to be seriously hot when you applied the handbrake.
The bit where the pads are cool slower than the rest of the disk and bingo. I have done this by sitting with my foot on the pedal after hammering to a stop after some flat out driving in the old Audi.
Could also be stuck as you mentioned, see if its abnormally hot compared with the other when you get in.

 

If its a knocking it could be a cracked disc. I've cracked a couple and it sounds and feels like there's a loose flap of tread on the tyre.

 

Car stood so calipers partially seized.
LSD on it's way out.
CV joint on it's way out.

Could be any of those 3, I'd guess the caliper for a start.

 

Doubt its a seized caliper.

Talking from experience mine didn't knock on braking. It just felt the handbrake was always on!