A8 starts to vibrate while braking

Hello, Leutz, it's a very disgusting problem. So here's the story from the beginning. I'm on my way as usual, brake wear indicator, I think I'm okay, I'll get new coverings. New coverings brought, rims down and fix the coverings are still impeccable. Ergo cable break. well not further important, wheels back on start starting from 80 beats the steering wheel. All right, get down there and balance. I'm still hitting. etc. Meanwhile, new disks and new coverings are in it. then still new bearings pressed into the lower crossbars, because they were also muddy. all other warehouses checked. Conclusion, it's okay. Test drive and again, when I had to worry about this problem today, I found that everything comes from behind, accelerated down to 140 then it comes to hit or hit. viebre and this you can start to feel at the seat and it is transmitted to the whole front construction and the steering wheel. Does anyone know this problem??
I'm grateful for everything, because that's what makes me crazy
Vehicle A8 Bj:97 4.2L
So looooooooong...