Gerbii40,

I think what you are experiencing is normal. My Sirion sounds like a there is sandpaper on the discs and a sack of rusty nails on the pads and all it is, is the discs corroding overnight and the first few applications of the brakes is merely the pads rubbing the corrosion away. After that all goes quiet. The problem is worse on lightweight cars because the noise is not so suppressed.

It is surprising just how much corrosion occurs on a disc brake even overnight. If you live near the coast expect the issue to be exacerbated, but even inland on a cold night a very thin film of corrosion will appear and is very normal. It just sounds very loud and very bad but it isn't.

You have checked for pad wear so you shouldn't worry too much. Having said that Sirion Original Equipment Manufacturer (OEM) discs are known to corrode very quickly and have a short life span. I know this for a fact and it was also my experience.

I bought my Sirion at 18 months old from a coastal area and the discs were in a very bad way. The inner surfaces viewed through the air gap for disc ventilation were well rotted through and the outer surfaces were looking nasty, and when I got them off it was obvious just how badly they had corroded - in the bin and fit new ones. I replaced with some cheap after-market discs and pads and all is well. My advice to you is get the front brake discs and pads replaced. Brakes are important.

There are plenty of after-market ones (don't buy OEM ones) because they are very expensive. Brakes are designed to wear and be replaced as required and it is a very simple job. I can get a disc from £20 delivered and pads just as cheap.

Hope it helps.

Regards