Ride comfort and masses — for improved vehicle ride comfort over typical road inputs, which mass property should be minimized to reduce harshness transmitted to the body?

Introduction / Context:
Vehicle ride comfort depends on how the suspension isolates the body from road irregularities. The system can be modeled with sprung mass (body supported by springs) and unsprung mass (wheels, tyres, hubs, a portion of suspension links and brakes). Lowering the unsprung mass reduces the force transmitted to the sprung mass when the wheels follow high-frequency road inputs.

Given Data / Assumptions:

• Standard passive suspension with springs and dampers, no active control assumed.
• Road inputs contain significant high-frequency content that primarily affects the unsprung assembly.
• Goal is to improve comfort without changing primary spring rates or damping drastically.

Concept / Approach:

The unsprung mass moves almost in phase with the road at higher frequencies; the force transmitted through the spring is roughly proportional to the product of unsprung mass and its acceleration. Minimizing unsprung mass lowers this force and improves isolation. Reducing sprung mass does not necessarily improve comfort, and very low overall vehicle mass can increase sensitivity to disturbances. Therefore, engineering practice prioritizes lightweight wheels, tyres, brake hardware, and sometimes inboard brakes to cut unsprung mass for better ride and grip over rough surfaces.

Step-by-Step Solution:

Verification / Alternative check:

Quarter-car models show that decreasing unsprung mass reduces body acceleration and tyre hop, aligning with accepted ride-handling trade-offs.

Why Other Options Are Wrong:

Minimizing sprung mass is not a primary path to comfort and can raise natural frequency. Minimizing total vehicle mass is driven by efficiency, not ride comfort. Therefore “all of these” is not correct.

Common Pitfalls:

Confusing handling objectives with comfort; assuming heavy wheels improve stability while they actually increase impact harshness.

Final Answer:

unsprung mass is kept minimum