Auto Balance Lab Worksheet
Student Name: ________________________________ Date: ______________
Class: ______________ Score: ____ / 25
Automotive STEM Lab Grade 5 Science & Math
Tire Tech: The Science of Wheel Balance
Target Standard
Forces & Algebraic Balance
Service Bay Briefing: Why Wheels Must Stay in Balance
Read carefully before starting the lab questions
When a car cruises at 60 miles per hour on the highway, each wheel assembly spins over 800 times every single minute! At that blistering speed, even a tiny imperfection—such as a patch of dried mud or a manufacturing variance of just half an ounce (\(0.5\text{ oz}\))—creates an uneven outward pulling force known as centrifugal force. This uneven force causes the wheel to wobble and hop against the pavement instead of rolling smoothly.
When a tire is out of balance, the driver feels violent vibrations traveling up through the steering wheel and car seat. Left unfixed, this shaking damages expensive wheel bearings, strains suspension springs, and creates irregular flat patches called “cupping” on the tire tread. Unbalanced tires wear out thousands of miles sooner and make emergency stopping less reliable.
Automotive service technicians solve this problem using high-tech dynamic spin balancers. The technician mounts the wheel on a motorized spindle that spins the tire at highway speeds while sensitive digital sensors detect exactly where the heavy spot is located. To restore equilibrium (equal balance of forces), the technician attaches small lead-free counterweights to the outer or inner rim directly opposite the heavy spot. When both sides exert identical forces, the wheel spins in perfect harmony.
Heavy Spot
Uneven weight pulling outward when spinning.
Counterweight
Weight placed opposite heavy spot to cancel shake.
Equilibrium
Equal opposing forces: \(\text{Side A} = \text{Side B}\).
Section 1: Pit Stop Reading Check (9 Points)
Cite evidence from the technical briefing
1. What warning signs and mechanical problems occur when a vehicle drives with unbalanced wheels?
3 pts
2. How does an automotive technician use a counterweight to create equilibrium on a spinning wheel rim?
3 pts
3. Shop Math: At 60 mph, a wheel rotates 800 times per minute. How many times does it rotate in 6 minutes?
3 pts
Total Rotations _______ rot.
Auto Tech Balance Lab • Page 2 of 2 Student Name: ________________________________
Section 2: Wheel Rim Balance Scales (6 Points)
Find unknown weight \(w\)
Like a wheel balancer, both sides of the equal sign (\(=\)) must balance. Solve for the missing weight (\(w\)).
Rim A • Front Left 2 pts
\(16\text{ oz} + w = 35\text{ oz}\)
Show work:
\(w =\)
___ oz
Rim B • Rear Right 2 pts
\(4 \times w = 64\text{ grams}\)
Show work:
\(w =\)
___ g
Rim C • Performance 2 pts
\(2w + 14 = 48\text{ oz}\)
Show work:
\(w =\)
___ oz
Section 3: Vehicle Weight Distribution Challenges (6 Points)
Solve the automotive balance equations
4. Front Axle: Left wheel carries \(685\text{ lbs}\). Right wheel carries \(590\text{ lbs}\) plus ballast plate (\(p\)).
3 pts
Solve: \(590 + p = 685\). How many pounds of ballast (\(p\)) must the pit crew add to balance the axle?
Ballast Plate (\(p\)) _______ lbs
5. Service Van Cargo: Left locker holds 3 toolkits (\(t\)) + a \(75\text{ lb}\) jack. Right locker holds a \(285\text{ lb}\) welder.
3 pts
Solve: \(3t + 75 = 285\). What is the balanced weight of one toolkit (\(t\))?
Each Toolkit (\(t\)) _______ lbs
Section 4: Master Tech Multi-Wheel Diagnostic Challenge (4 Points)
Final Problem • 4 pts
SUV Spin Balancer Readings:
FL: 1.75 oz FR: 2.25 oz RL: 1.50 oz RR: 2.50 oz
A. Calculate total ounces added to balance all 4 tires.
Total Weight: ______ oz
B. If using \(0.25\text{ oz}\) clip weights, how many total clips are needed?
Total Clips: ______ clips
