More info, please. Does wheel position, left, right, straight ahead change the sound?
What is a loud vibration? Loud is a sound. Vibration is a movement. What does it sound like? Is the sound high pitched or low, constant or sharp repetitive sound? Where and what is shaking? Please be specific if you are to get some help. Was this sudden in onset or has this been getting gradually worse?
Have you serviced, changed or modified anything recently? Have you experienced any unusual event, such as an accident, running over anything, hitting a curb? Is tire wear normal? Are there any signs of leaking fluid or grease on exposed surfaces of the suspension or chassis?
When you say it stops when you take the car out of gear, when in gear does the noise get louder with speed or rpm? By that I mean is it as loud and vibrate as much at 3000 rpm in gear in every gear at that rpm, or does it get louder in the higher gears?
What happens when driving at 60 mph in 4th gear when you depress the clutch and let up on the gas and coast? Does the condition change if you are going 60 in 4th and push in the clutch, let up on the gas, shift into neutral then let up on the clutch and coast?
Do you feel the vibration in the steering wheel? Do you feel it in the clutch pedal when changing gears?
Everything above could be important in figuring out your problem.
