Possibly warped rotors, loose wheel bearing, or a defect in a tire. Inspect your tires carefully, looking for bulges, or any other abnormality. If you find none, then you will need to check the wheel for looseness, and if it is not loose, then have the rotors removed and turned. Replace the front pads at this time. I would suspect you will find the rotors are warped. When replacing the wheel after service, be sure and tighten the lugs nuts to the proper torque, (found in you owner's manual). Tighten to tight and the rotors will warp again.
This is my question Turns out it was a badly worn right axle Vibrating while braking is a warped rotor.
You have warped rotors. They will need to be removed and trued or replaced. Causes of this are lug nuts overtightened, or heat from heavy braking at high speeds.
Check the entire front end. Wheel bearings, ball joints and tie rod ends can all wear and call this problem.
the brake rotars are out of round or warped.have them machined
You rotors are warped and will need replaced/resurfaced.
Tire out of balance, bent wheel, or defective wheel bearing are common causes.Tire out of balance, bent wheel, or defective wheel bearing are common causes.
Your brake rotors or drums are warped and need replaced.
Most trucking companies do not require you to do high speed braking for speeds of the extent. Normally when you are driving a truck, your speed shouldn't exceed 70 MPH due to speed limits. They will teach you high speed braking though to prepare you for a worse case scenario.
White or blue smoke, and oil in the coolant are two fairly reliable signs of a blown head gasket or crack in the block or head. If it was the brakes (warped rotors also cause vibration), you would feel it vibrating faster at high speeds with light braking, and slower at lower speeds.