chances are that your rotors are warped change them and ur problem will more than likely be fixed if not check your tie rod ends
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To confirm rotors, take vehicle up to 30-40mph or 50-60kph cruising speed and then gently depress brake pedal(brake mildly leaving foot on brake). If the pedal feels like it's "pulsing" then chances are REAL good it's your rotors. If it seems that the steering wheel shakes slightly from side to side, then it's likely you have steering component failure-you can further determine this by jacking the front end up by the frame(use jack stands, PLEASE) and physically push and pull on the various rods and joints of your steering system to check for wear. Also look at all the moving joints to see it they still have evidence of grease-it's what any repair shop would do.
Wheels require balancing.
have the tyre checked for balance
have front suspension checked
Aside from the aforementioned imbalanced tire and alignment (which could be incorrect toe in, castor, or camber), worn/damaged steering components, worn shackle pins, faulty wheel bearings, and damaged rims are another possibility.
Check tire balance or wheel bearings in front axle
Probably wheel balance.
possibilityThe car is out of alignment or you have a wheel out of balance.
1. out of balance wheels 2. misaligned front end 3. worn out steering dampner.
Bad tires, out of balance , wrong wheels , bad tie rod end.
problem with your transmission in 5th gear
The fact that it's a piece of junk chevy, get a mustang. Ford all day.
Tires out of balance, bent wheel, or defective tire.