Hi there I have some rusting on the outer of the back discs does this mean the pads need replacing.

Usually when that starts to happen the otherside, behind the disc shield, will look even worse.   You could try and replace pads (and clean up carrier slide surface areas and apply ceretec grease) but most would suggest replacing discs and pads together.  How much is left on the pads that are in there?  How significant is the lip on the non contact area of the disc surface?

 

It may not be a MOT fail initially if the braking performance is not too affected. 

Edited 7 June, 20179 yr by TheClient

The pads don't look to bad,and there's not much of lip between the rust and the rest of the disc.theres about 10 mm on the pads don't no whether this is good or bad...

I'll try to look up later on, if you search for the correct pads on a brake manufacturer site, it should give you friction depth  or a pad diagram. I would guess at least 25mm maybe 30mm.

 

You could try removing the pads, cleaning up sliding surfaces, greasing etc. But you are probably going to have to replace. Make sure you id your disc size if doing replacements yourself to make sure you get correct parts.

The discs on my ford have done the same.

From what I can find, total new depth of (edit: each) rear pads without backing plate about 11mm i.e friction material. Min friction material 2mm.. Backing plate probably adds 4-6mm but may depend on manufacturer - look at their website to confirm exactly. 

Edited 7 June, 20179 yr by TheClient

Thanks for your input fellas..if I remember correctly on the last mot in October it said uneven brake pad wear.or something along those lines.

Yes, when I bought our vRS last year, at 5 years of age / 33k miles, they looked a bit worse than yours. There was still a decent amount of pad left too, (maybe a little less than half), must have been the originals.

 

There was an advisory for pitting and scoring of surface but not significantly weakening braking performance.  I left it a few months and then replaced discs and pads front and rear and changed brake fluid. Once off, the discs looked worse on the inside surface than how it appeared from the outside.  Also made sure I cleaned up the slide surfaces on the carriers too and new retaining springs.

 

In our mk5 Golf, I changed the rear discs and pads at 8 years 60k miles, and I could of probably done the pads only. No uneven surface or pitting. The discs were getting close to the wear limit though. Never did the fronts discs or pads when I sold at 9.5 years 68k miles and they still felt good, discs looked ok and pads had about 35% left. All original.

 

Maybe they don't make em like they used to.

Just had a look at it with me dad..I think a stone has got stuck in between the pads and disc.

My 2012 vRS had replacement pads and discs all round at 42K miles due to excessive rusting.  Never before have I owned a car with discs that corroded so fast.  The edges of the discs were crumbling away.  Local Skoda dealer wanted £550 to replace all discs and pads; local VAG specialist did the job for £204.20p.  After replacement the stopping power was noticeably better and the brake pedal feel firmer and more progressive.  The original discs would rust if the car wasn't used for 2 days.  The replacements were OK after the car had been left for 5 days.