If a vehicle "dives" during braking with a hydraulic brake system, what could be the possible cause?

When a vehicle "dives" during braking, it typically indicates that there is an issue with weight transfer as the vehicle decelerates, causing the front of the vehicle to dip down more than usual. A defective metering or combination valve plays a critical role in managing the brake pressure distribution between the front and rear brakes. If this valve is not functioning properly, it can result in uneven braking force applied to the wheels, leading to increased weight transfer toward the front of the vehicle during braking.

This can amplify the "diving" effect as the front brakes may engage more aggressively than the rears, exacerbating the dip. A properly functioning metering or combination valve is essential for balanced braking performance, ensuring that the vehicle remains stable while stopping.

While low brake fluid level, worn brake pads, or incorrect tire pressure may affect overall braking performance or stopping distances, they do not directly contribute to the specific issue of the vehicle diving during braking in the same manner that a defective valve does.