when ever i am driving over 80km and mash a heavy brakes the car steering pulls to the left. if i am driving kinda slow or just apply a little brakes it is ok. what can be the cause of this. it is a ck2 lancer (not four wheel disc brakes) brakes and drum.

Possible causes could be:
1. A defective front left tyre. Jack up the car and inspect the wheel, check for wear and to see if the tyre is underinflated.
2. A worn and warped rotor. Rotors need to be resurfaced.
3. Check alignment and camber angle.
4. Steering ends.

Those are the first things that came to mind but that should cover it and by process of elimination you should find out the cause of the problem and know what needs to be repaired/fixed/checked or just done.

_________________