Have you had a front-end alignment? When you remove parts from the front end, you need to have this done.
You have a "Warped" brake rotor. It needs to be replaced
A brake pad is the friction surface, replaced as it wears, between the caliper and the rotor.
Signs of a worn brake rotor include vibrations or pulsations when braking, squealing or grinding noises, and uneven wear on the rotor surface. A brake rotor should be replaced if it is too thin, has deep grooves or scoring, or if it is warped and causing braking issues. It is recommended to replace a worn brake rotor as soon as these signs are noticed to ensure safe braking performance.
Most often this is cause by a warped rotor. In most cases the rotor can be turned and returned to a perfect condition. In some cases the rotor will have to be replaced. Have your brake system inspected and repaired.
You will need to inspect the rotor to see if it needs replacing. Track marks or thinning areas mean that it needs to be replaced. If the rotor is very smooth and flush with the edge of the rim edges then you don't need to place the rotor and your issue is likely with the brake pads or discs.
The brake rotor functions similar to the breaks on a bicycle. Each brake rotor contains a rotor and a brake pad. When the brake is applied, the brake pads squeeze the rotor, causing the wheels to stop.
You need the front rotors machined or replaced.
The minimum brake rotor thickness for a 2002 Mitsubishi Eclipse is 1.17 inches. When it falls below this thickness, braking performance will suffer and must be replaced.
Brake pads are worn and the squealer tab is rubbing on the rotor. Pads will need replaced.
A pulsing brake pedal indicates a warped disk rotor and that means the rotor needs to be replaced. In that case, they should both be done at the same time.
A bad brake rotor in the front or rear can cause a pulsation in the brake pedal when pressure is applied on the brake pedal when the vehicle is in motion. The brake rotor can be measured with a micrometer to be sure it is within specs and has enough material to be legally resurfaced on a brake lathe. In most cases now rotors are simply replaced with new ones to be cost effective.
The brake pads have a small metal piece which makes he brake squeak. This means it's time to change your brakes. The longer you let it squeak, the more damage it does to you rotor. Still the rotor can be resurfaced or if needed replaced.