Brake pedal pulsating after drop

[1sickcrewcab]

My dad and i just installed his djm drop spindles and djm lowering springs on his 99 2dr Tahoe. Was working fine until we did the drop, when braking the brake pedal starts pulsating. You could feel it on your foot when braking the pedal jumping up and down. Has all new front suspension parts, new rotors and a new abs sensor. We even took off rotors to get resurfaced and installed old abs sensor, but nothing has worked. What else could it be??? Its really annoying my dad.Thanks guys

 

[sewlow]

Warped drums? It's common.

 

[1sickcrewcab]

The drums are about a year old and we didn't do anything to the drums. Truck was working fine until we installed the front drop kit. We're going to bleed the lines next just to see what happens.