2016 sportback brake problems

[cjp2k]

My wife's car is a 2.0 tdi manual on a 16 plate with 15k miles

The wife drove my b9 and said the brakes are much stronger..

I drove her car and noticed hers didnt bite as quickly as mine.

Anyway sat at traffic lights foot on the brake and the pedal drops from under my foot and made a grating noise

Foot off brake and it springs up and continues but still spongy

Audi cant get it in for a month.. Waiting on audi breakdown to come and see what they say

Any ideas what it could be before I get a no fault found report back

 

[Meemo]

could be trapped air and need a bleed. You tend to get a complete mixture of solid to spongey, responsive to nothing when there is air in the line, any garage barry could bleed the brakes for you, cant picture it costing much as only take a few minutes to do each brake.

 

[Meemo]

just to add.. mine got stuck and sounded like a truck when i had air in the line, as well as the above symptoms, not exactly the same but that was due to not bleeding my brakes properly after me and a friend change the disks and pads on my old a4.

 

[cjp2k]

Thanks my guess was air.. But hows it got in as no brake work done

Also wont cost anything as under warranty but i have had a number of dealings with audi and no fault found

 

[Meemo]

maybe from factory? who knows, let us know how it goes as the only thing I can think of other than brake pads down the the metal/gouged disks... is air in the brake lines.
really unlikely, but isnt something between one of the pads and the disk? I imagine it would of been ground away from braking, but pretty easy to pop the pads out and look for gouging/discoloured disks or damaged pads.

 

[cjp2k]

Well the cars been recovered by the AA and at the Audi dealer, waiting on a hire car to be delivered

AA guy said its not right, and thinks it could be the master cylinder or the servo?

Checked all brakes and discs and pads are all fine

Dealer has 48hours to diagnose the problem, but with the weekend its likely to be Tuesday we get anywhere