Is it normal for the brake discs on my 19/20 Focus to rust after only a day or two of sitting on the drive? If I take the car for a 60 mile drive of mixed motorway and town driving, the front discs do clean up a bit, but the rear discs don't clean off the rust even after a 1000 mile journey. The car seems to brake ok as proved by filling the boot and folded back seats with enough Belgian beer as it can safely carry back to the UK and driving from Antwerp back to Worcester in (almost) one go. Thoughts anyone?

That doesn't seem quite right to me. Your car is about 3.5 years old so how many miles on your car? Discs indeed do rust overnight but with 2 revolutions of the wheels with the brakes on clears the discs to like new.

There's a possibility the brake pads may be near their end of useful life. 

57 minutes ago, tazzman600 said:

That doesn't seem quite right to me. Your car is about 3.5 years old so how many miles on your car? Discs indeed do rust overnight but with 2 revolutions of the wheels with the brakes on clears the discs to like new.

There's a possibility the brake pads may be near their end of useful life. 

It has only done 18,636 miles from new.

Perfectly normal.  Front to rear bias is about 80:20.  Rear brakes are only used under heavy braking so the rear discs won't clear unless you purposely jump on the anchors...

REAR

FRONT

even brand new disks and pads will rust up within a few days as its metal to metal with no oil to protect, if there was you'd never stop.

A devil of a problem, exacerbated by the electric handbrake which is either on or off, unlike my Mazda with it's normal handbrake, which I can use to clear the discs by having it on lightly while driving - for a short distance!

 

OMG. You should Never use the handbrake to clean a brake disc. I've not seen a car for decades where the handbrake operates the rear caliper. But anyway back when that was the case it was not recommended because it caused cable stretch.

9 hours ago, RMurphy195 said:

A devil of a problem, exacerbated by the electric handbrake which is either on or off, unlike my Mazda with it's normal handbrake, which I can use to clear the discs by having it on lightly while driving - for a short distance!

 

Yes, aggre with you. Electric handbrakes don't help. We used to have to use the manual handbrake to bed rear pads in if the the customer was too tight to buy rear discs . Bit of a drive with handbrake on slightly soon sorted it. 

Dodgy garage you worked at back then Ian lol. Bet whoever did that 'running in' also did handbrake turns lol.

No handbrake turns required , just apply the handbrake lightly. Never worked at a dodgy garage. All main dealer reputable places in the 43 years I've been a mechanic. 

1 minute ago, iantt said:

No handbrake turns required , just apply the handbrake lightly. Never worked at a dodgy garage. All main dealer reputable places in the 43 years I've been a mechanic. 

Technique is especially useful in the run-up to MOT time, no need to find a quiet road with no following traffic to do the "italian tune-up"!

I eventually got around to replacing both the rear discs and pads with Bosch from Parts in Motion. An easy job to do and putting the electric handbrake in and out of maintenance mode was also simple. The only challenge was winding the pistons back in which I did with a good pair of snipe nose pliers.