Suspension Systems Questions and Answers

Answer: C

Damping force rises with the speed at which the piston moves, which is why a damper resists a sharp movement strongly and a slow one hardly at all. A spring resists displacement. The distinction is fundamental to understanding suspension behaviour. The order in which the effects act is what decides the outcome, so it is worth establishing first. The shared behaviour explains why these belong together and the differences explain why both exist. A limit that survives making every external component ideal is an intrinsic one, and worth knowing for that reason.

Answer: D

Bump damping is kept soft so the wheel can rise over an obstacle without jacking the body up, while rebound damping is stronger to control the energy the spring returns. The ratio is typically around one to three. Equal damping rides badly. Checking which component actually carries the load settles most questions of this kind at once. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: A

Stiff bump damping resists the wheel rising, so the force passes into the body and the ride becomes harsh. Insufficient rebound damping causes float. Each direction produces its own characteristic complaint. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. The order in which the effects act is what decides the outcome, so it is worth establishing first.

Answer: B

Pushing a corner down and releasing it should produce one return and settle, and further oscillation indicates a worn damper. Ride height is set by the spring, not the damper. The bounce test is crude but it identifies a badly worn unit. The shared behaviour explains why these belong together and the differences explain why both exist. Most errors here come from carrying across a result from a neighbouring case where it does not hold. A single measurement chosen to respond to the one asymmetry beats several that respond to shared behaviour.

Answer: C

Oil on the body of the damper means the seal has failed and the unit can no longer generate damping force. A light film is sometimes acceptable but a run of oil is not. Dampers are replaced in pairs across an axle. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Naming what changes and what stays the same is the reliable route through questions of this shape. Checking which component actually carries the load settles most questions of this kind at once.

Answer: D

A monotube carries a floating piston separating the oil from high pressure nitrogen, which prevents aeration and allows the unit to be mounted either way up. Twin tube designs use a foot valve and a reserve annulus instead. Monotubes dissipate heat better. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Framing the question as which quantity the change acts upon makes the answer follow without calculation.

Answer: A

Without pressure the oil cavitates behind the piston at high velocity, forming bubbles that collapse and destroy the damping. Nitrogen at high pressure suppresses it. The symptom is a damper that works when cold and fades on a rough road. Most errors here come from carrying across a result from a neighbouring case where it does not hold. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: B

Independent suspension gives each wheel its own linkage, so a bump at one wheel does not disturb the other and unsprung mass is reduced. A de Dion axle is a compromise that keeps the wheels parallel but removes the differential from the unsprung mass. Naming what changes and what stays the same is the reliable route through questions of this shape. The order in which the effects act is what decides the outcome, so it is worth establishing first. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: C

The strut carries the spring around the damper and is bolted to the hub carrier, so it locates the wheel laterally as well as damping it. It is compact and cheap, which is why almost every front wheel drive car uses it. Camber control in roll is its weakness. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Checking which component actually carries the load settles most questions of this kind at once. Working one numerical case through both cases side by side fixes the distinction better than any rule of thumb.

Answer: D

Because the strut needs only a single lower arm and a top mounting, it frees the space that an upper wishbone would occupy across the engine bay. It is also cheap. Its camber control is poor and it needs a tall mounting, so the bonnet is higher rather than lower. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. The shared behaviour explains why these belong together and the differences explain why both exist.