Vibration when braking

[Carbonman]

Hi all
I've got an audi a6 c7 allroad, it's the 3.0bitdi.

Im having an issue when I brake with vibration.
If I brake at 60 it's fine until it hits 40 at which point it starts to judder and vibrate.
No vibration if I brake at 30 for example..
Hace had the discs replaced thinking it was that, but also noticed the wheel nuts seemed to be coming loose. I run 20"wheels with 15mm hubcentric spacers to clear the brake caliper.
The issue went for 2 months but now has returned.
It's just gone through MOT too.
Any idea where to look? Seems unlikely that the discs have warped I don't drive hard at all and did bed them in.
But I'm not sure where else to look nothing obviously seems worn on the suspension.

Any suggestions? No vibration at all unless braking as described..

Thanks

[annodomini2]

As you are running spacers, are the bolts long enough?

[anonymous-user]

If the issue went then it was run out on the discs. But now that it's back you need to find out why.
Were the new discs properly fitted? Any debris on the hub will lead to run out again and vibration after a few weeks / months.
Or is there a problem with one of the hubs? Over torqued bolts?

[Carbonman]

So I've been advised to torque to 140 which I'm aware is pretty high.. Could over torquing cause this?

[Crafty_]

I'd get rid of the wheels and spacers, go back to stock set up and see if the issue persists.

[anonymous-user]

140 what?

Take the wheel spacers off and see if that changes anything would be my first check.

[Carbonman]

140nm

Cant take the spacers off as the wheels won't clear the brake calipers.. Will be trying original wheels tomorrow tho to see if the problem stays with wheels or not...

gottans said:

140 what?

Take the wheel spacers off and see if that changes anything would be my first check.

[Carbonman]

Ok changed wheels today to originals and the problem remains.
One thing I noticed is when putting the passenger side front on with the wheels tight you can move the wheel and the spacer moves rotationally on the disc, see video. This was when the bolts were tight but not torqued. When I torqued to 140 it stopped.
I'm thinking that shouldn't be possible if the bolts are tight and located?
https://photos.app.goo.gl/fuadYzXXNwnRRRot9
Video attached