Sunday's cold was certainly bitter.
Unfortunately, I took 2 steps back in my driving this weekend. My instructor (and previous one as well) thought I haven't been smooth enough, and he instituded a new driving technique for me: brake, throttle, turn; but neither at the same time. I was braking 100 ft before the real braking point, gently apply gas then turn. That was so f*%@# frustrating. But I am a student and have to trust the instructor so I went along through the weekend. I don't remember passing anyone but my left arm/shoulder had a very good workout
Sunday towards the last 5-6 laps of the 2nd session, after hard braking into T1, a pronounced vibration started on the steering wheel. Cooled down the car for a lap and came into the pits, then went out again; the vibration was gone. Then, last session while solo, on the 3rd or 4th lap, again under hard braking, the vibration came back; drove at a slower pace for about 2 laps and pulled into the pits and ended the day.
All looks alright from the outside, pads/rotors etc., I am not sure what might be happening. Sure seems to be related to heat though. May be the rotor holes are filled with brake dust and it is heating and cooling non-uniformly. Any ideas?