please help : car vibrates heavily

Because you describe the brake pedal having an effect, this is most likely wheels / tires / balance OR improperly fitting wheels or nuts which are not allowing the wheels to fit "centered" and or tight ................OR a front end problem IE something out of line, loose, or broken............OR brake problems in some cases


First "start" to try to eliminate. Use a qualified friend if possible. "Two heads." Stay sober while doing this. Remove all wheels and examine carefully for such things as interferance between center hole and rear axle center, or front hubs. If alloy wheels with shouldered nuts take care that the shoulders are not too long. In other words look CAREFULLY at the wheels, studs, nuts, and the way they mount

Jack up the rear safely, run the car in different gears. Feel for vibration. You need to support it under the rear axle. Listen, feel, and look

Do a careful test drive. Have a friend watch 'drive by' and look for wobble

IF POSSIBLE find at least a pair of additional mounted / balanced tires to try for test drives. Switch them front / rear. ROTATE the tires up on a jack, feel for loose, look for wobble.

READ the service manual. Go through the front end, looking for looseness. To check ball joints, you need to jack under the lower arms. This is also best done with two people

This can be caused by an "additive" problem, that is, one front tire (example) out of balance, coupled with worn front end parts that allow slop and movement.