Suspension

Every suspension system answers 3 things:

  1. How is weight supported? → Spring

  2. How is motion controlled? → Shock/Strut

  3. How is stability maintained? → Sway bar

If you get lost, come back to this.

TYPES OF SUSPENSION (HIGH PRIORITY)

  1. MacPherson Strut (MOST COMMON FRONT)

    • What it is

    • Strut = shock + spring combined

    • Acts as a structural member

    • No upper control arm

    • Parts

    • Strut assembly

    • Lower control arm

    • Steering knuckle

    • Tie rod

    • Sway bar + links

    • How it works

    • Strut supports weight AND controls movement

    • Wheel pivots at strut + lower ball joint

    • Pros

    • Simple

    • Cheap

    • Compact

    • Cons

    • Less precise handling

    • Limited camber control

Test Clue: If there’s no upper control arm → it’s MacPherson

  1. Double Wishbone (A-Arm Suspension)

    • What it is

    • Has upper AND lower control arms

    • Shaped like “A” or wishbones

    • Parts

    • Upper control arm

    • Lower control arm

    • Coil spring + shock (separate)

    • Ball joints (upper + lower)

    • How it works

    • Keeps tire flatter during turns

    • Better control of alignment angles

    • Pros

    • Better handling

    • More control

    • Cons

    • More complex

    • More expensive

Test Clue: If you see two control arms → double wishbone

  1. Multi-Link Suspension

    • What it is

    • Uses 3–5 separate arms (links)

    • How it works

    • Each link controls a different direction of movement

    • Pros

    • Best ride quality

    • Best handling

    • Cons

    • Complex

    • Expensive

Test Clue: “Multiple arms” or “independent links” = multi-link

  1. Solid Axle (Live Axle)

    • What it is

    • Both wheels connected by one solid beam

    • Where used

    • Trucks

    • Rear suspension

    • How it works

    • One wheel movement affects the other

    • Pros

    • Strong

    • Good for heavy loads

    • Cons

    • Rough ride

    • Poor handling

Test Clue: “Both wheels move together” = solid axle

  1. Independent Suspension

    • What it means

    • Each wheel moves separately

    • Includes

    • MacPherson

    • Double wishbone

    • Multi-link

COMPONENT DEEP DIVE

Coil Spring

  • Supports vehicle weight

  • Absorbs bumps

  • Determines ride height

Important:

  • More coils = softer

  • Fewer coils = stiffer

  • Sagging = worn spring

Shock Absorber

  • Controls spring motion

  • Prevents bouncing

Key:

  • Does NOT support weight

  • If bad → car keeps bouncing

Strut

  • Shock + spring

  • Structural part

Key:

  • Replaces upper control arm

  • Affects alignment

Sway Bar

  • Connects left/right suspension

  • Resists twisting

Key:

  • Reduces body roll

  • Does NOT affect ride height

Sway Bar Links

  • Connect sway bar to suspension

  • Transfer force

Key:

  • Common failure = clunking

Ball Joint

  • Pivot point

  • Allows steering + up/down movement

Key:

  • Worn = loose steering or clunk

Control Arm

  • Connects wheel to frame

  • Allows vertical movement

Tie Rod (Steering)

  • Connects rack to wheel

  • Controls direction

STEERING SYSTEM BASICS

Rack and Pinion

  • Most common

  • Steering wheel → rack moves side to side

Tie Rods

  • Inner + outer

  • Transfer motion to wheels

Steering Knuckle

  • Connects suspension + steering

SYMPTOM → CAUSE (TEST GOLD)

Clunking over bumps

  • Sway bar links

  • Ball joints

  • Bushings

Excessive bouncing

  • Bad shocks

Leaning in turns

  • Sway bar issue

Sagging vehicle

  • Weak spring

Loose steering

  • Tie rods or ball joints

TECHNICIAN A / B LOGIC

Example thinking:
Tech A: Shocks support vehicle weight ❌
Tech B: Springs support vehicle weight ✅
Answer = B

Common traps

  • Shock ≠ support weight

  • Sway bar ≠ ride height

  • Strut = structural

HOW TO ANSWER HARD QUESTIONS

When stuck, ask:

  1. Is this about weight? → Spring

  2. Is this about movement control? → Shock/Strut

  3. Is this about leaning? → Sway bar

  4. Is this about steering? → Tie rod

MEMORY SHORTCUT (THIS IS YOUR LIFELINE)

Say this:
“Spring holds, shock controls, sway bar stabilizes.”
Then add:

  • Link = connects

  • Ball joint = pivots

  • Tie rod = steers

Real talk (just for you)
You’re not underprepared—you’re overwhelmed by volume + pressure.
The goal tonight is NOT:
❌ memorizing every word
✅ recognizing patterns and functions
Because on that test, your brain will go:
“Okay… leaning = sway bar… I know that.”
That’s how you pass.

Camber

  • Definition: The angle of the wheels in relation to the vertical axis when viewed from the front of the vehicle.

    • Positive camber: The top of the tires leans outward from the vehicle.

    • Negative camber: The top of the tires leans inward toward the vehicle.

  • Effects:

    • Positive camber can improve cornering stability, but may lead to uneven tire wear.

    • Negative camber increases grip during turns but can cause tire wear on the inner edge.

Toe

  • Definition: The angle of the tires in relation to the longitudinal centerline of the vehicle when viewed from above.

    • Toe-in: Front of the tires points towards each other.

    • Toe-out: Front of the tires points away from each other.

  • Effects:

    • Toe-in can provide stability in straight-line driving but can cause increased tire wear.

    • Toe-out can improve responsiveness but may lead to instability.

Alignment Overview

  • Purpose: Proper alignment ensures that all wheels are parallel and correctly positioned relative to each other and the road.

  • Benefits:

    • Improved handling and steering performance.

    • Better fuel efficiency due to reduced drag.

    • Extended tire life by minimizing uneven wear.