Brake problem when driving at high speed

My friends vehicle 106 Qs, while we were balancing the other day (the vehicle was in the chocks), we noticed that the vehicle had a tremor when braking. Then I checked this when I was on the road and whenever my speed was 120+ and I applied the brakes, a little shake occurred in the car until my speed was 120-. What could be the reason for this? I don't have any problems in 120-

probably there is curvature of the brake discs

discs & nbsp; too few & nbsp; turning turns

We also have new controls on the brakes ...

The problem is definitely related to discs in my opinion, if it is not worn too much, it can be corrected with a small turning operation

Absolutely on disk. I changed my discs 3 days ago from the same problem, now like a monster.

let's see let's go monday let's see ... thanks for your comments guys ...