Why does chev optra vibrates while I am driving on flat road and on gear 5
I am experiencing a vibration problem while driving on flat road and on gear 5, I haven't listened while the car is on neutral simply because when car start vibrating, I pull off and stop for +- 1 min and then take off and then the problem will be gone, I haven't heard a noise while accelerating. The strange thing is "when i drive the car after resting it for some time, the rattling/grinding noise & vibrations go off, the drive becomes super smooth & silent." please help me find the problem.