If your vehicle is showing knocking sound from the front end when driving on gravel, here are the most likely causes and the parts you'll need to fix each one.
The sway bar links connect your suspension to the sway bar. When the ball sockets wear out and develop play, they create a very distinct, rapid knocking or rattling noise over small, repetitive bumps like gravel.
The rubber bushings that hold the sway bar to the vehicle frame can harden, shrink, or tear over time. This allows the metal sway bar to knock against the frame when driving over uneven surfaces.
The upper mounts connecting the struts to the vehicle body contain rubber isolators and bearings that degrade. When worn, the entire strut assembly can shift and knock against the shock tower on rough roads.
If caliper slide pins lack lubrication, are heavily worn, or if bracket bolts were left loose after a recent brake job, the brake caliper will rattle rapidly over gravel. This is a common post-maintenance issue.
Ball joints and tie rod ends are critical steering and suspension pivots. Excessive play here causes knocking over bumps and can lead to a dangerous loss of steering control if they fail completely.
The rubber bushings isolating the control arms from the frame can tear or collapse, causing metal-to-metal knocking during suspension travel on rough terrain.
Wear inside the steering rack and pinion assembly can cause a clunking or knocking noise that transfers through the steering column when driving over rough terrain.