With a silver front-wheel-drive hatchback perched on a lift and its wheels hanging free, Bayport mechanic Lena Ortiz asked a room of first-time car owners to watch one thing and one thing only: the twist. “If you can picture the twist moving through the car,” she said, tapping a paint marker against a bare axle shaft, “everything else starts to make sense.”

Ortiz’s Saturday clinic at Harborview Auto was billed as a beginner lesson on “what happens between the engine and the pavement.” Instead of formulas, she used a running narrative: the twist leaves the engine, passes through a series of parts, and arrives at the tires.

The example vehicle was a typical front-wheel-drive (FWD) passenger car — engine mounted sideways, transmission tucked beside it, and both front wheels driven.

The shop’s “flow diagram,” spoken aloud

Ortiz wrote a simple, labeled flow on a whiteboard and read it like a set of directions.

Flow (FWD compact car):

1. Engine crankshaft → 2) Flywheel (manual) / flexplate (automatic) → 3a) Clutch (manual) or 3b) Torque converter (automatic) → 4) Transmission (gearsets) → 5) Final drive (reduction gears) → 6) Differential (left/right split) → 7) Axles (half-shafts) + CV joints → 8) Wheel hubs → 9) Tires on the road

“Everything in that line is just handing off rotation,” she told the group. “The twist is still the twist — it’s just sped up, slowed down, redirected, or divided.”

Crankshaft and flywheel: where the twist is born and steadied

With the engine idling, Ortiz pointed to the crankshaft pulley at the front of the engine. It spun with a steady rhythm.

“The crankshaft is the first piece you can actually see doing the twisting,” she said. “It turns because the engine is firing.”

On a manual version of the same model, she said, the crankshaft bolts to a flywheel. On an automatic, it bolts to a thin flexplate.

A flywheel’s job, Ortiz said, is mostly about feel and steadiness. “It smooths things out so the twist doesn’t come in jerks,” she said, running her hand around a flywheel’s toothed edge sitting on a bench.

What changed here: not much that a student could measure in the room. What stayed the same: the twist stayed continuous, always moving outward from the engine.

Clutch (manual): a switch that can connect or separate the twist

Ortiz invited a student to press the clutch pedal in a manual trainer rig. As the pedal went down, the instructor held up two friction discs.

“When you press the clutch, you’re saying, ‘Pause the handoff,’” she said. “Let the engine keep twisting, but don’t send that twist into the transmission for a moment.”

When the clutch is released, the friction surfaces clamp together and the twist is shared again. “You feel it as the car starts to roll,” Ortiz said.

What changed: the twist could be interrupted or reconnected smoothly. What stayed the same: the direction of rotation stayed the same, and when connected, the twist continued down the line.

Torque converter (automatic): a fluid handoff that can slip on purpose

At the automatic training cutaway, Ortiz pointed to a round housing. “Here’s your handshake made of fluid,” she said.

Instead of clamping discs, the torque converter uses fluid flow to pass rotation from the engine side to the transmission side. “At a stoplight, the engine can keep spinning while the car isn’t moving,” she said. “That’s slip — and it’s built in.”

A student asked if that meant the twist disappears.

“It doesn’t disappear,” Ortiz replied. “It just doesn’t fully grab until you ask for it. And when it does, it can feel like it gives you a stronger shove off the line.”

What changed: the handoff could slip and feel softer at low speed. What stayed the same: the twist remained rotational motion traveling forward through the drivetrain once the car begins to move.

Transmission: choosing how fast the twist spins versus how hard it pushes

Ortiz moved to the transmission case and tapped it with a wrench. “This is where we choose the personality of the twist,” she said.

In lower gears, she explained in practical terms, the car feels eager but not fast. In higher gears, it feels calm and efficient.

“You’re trading spin for shove,” she told the group, careful to keep it in everyday language. “Same twist coming in, different twist going out.”

What changed: how quickly the outgoing shafts spun and how strongly the car wanted to move. What stayed the same: the motion was still rotational and still coming from the engine (losses aside).

Final drive: one more slowdown before the wheels

Ortiz pointed out that many FWD cars package the final drive gears inside the same housing as the transmission.

“This is the last big ‘slow it down so it can move the car’ step before the split to left and right,” she said.

When a student asked why it wasn’t all done in the transmission, Ortiz shrugged. “Packaging and drivability,” she said. “This is the part that makes the rest of the system feel like a normal car instead of a screaming go-kart.”

What changed: the twist typically slowed again and felt stronger at the wheels. What stayed the same: it remained a continuous rotational handoff.

Differential: one twist becomes two, and they’re allowed to disagree

With the car still in the air, Ortiz slowly rotated one front wheel by hand. The other wheel turned the opposite direction.

“That’s the differential doing what it’s supposed to do,” she said. “In a turn, your outside wheel needs to cover more distance than your inside wheel. So the differential lets left and right spin at different speeds.”

She emphasized that the differential isn’t “making power.” “It’s deciding where the twist goes,” Ortiz said.

What changed: the single incoming rotation was divided into two outputs, and wheel speeds could differ. What stayed the same: both sides still received rotational motion coming from the same source.

Axles and CV joints: delivering the twist while the wheels steer and move

Ortiz traced the half-shafts from the transmission to each front wheel. “These axles carry the twist out to the hubs,” she said.

At each end sat a CV joint. Ortiz wiggled one joint to show its range. “Front wheels have to steer left and right and move up and down with suspension,” she said. “The CV joint lets the axle keep sending twist even when it’s bent at an angle.”

A student mentioned hearing clicking on turns.

“That’s a common CV joint clue,” Ortiz said. “The twist is trying to get through, but the joint’s wearing out. You hear the argument.”

What changed: the twist’s path physically bent and flexed with steering and bumps. What stayed the same: the axle still carried rotation to the wheel hubs.

Wheel hubs and tires: where the twist becomes motion you can feel

Ortiz ended at the tire. “This is the only part that actually touches the world,” she said. “Everything else is just getting the twist here.”

When the tire grips, the rotation becomes forward motion. If it slips, the twist still exists — it just turns rubber instead of moving the car.

A brief detour: how the path differs in rear-wheel drive

Before dismissing the class, Ortiz sketched a second, shorter note under the first flow.

In a rear-wheel-drive (RWD) layout, she said, the transmission sends the twist down a driveshaft to a rear differential mounted between the back wheels. “Same story, longer hallway,” she said.

Flow (RWD, simplified):
Engine → clutch/torque converter → transmission → driveshaft → rear final drive + differential → rear axles → rear wheels

The lesson, she told the group, was to keep following the twist. “If you can name the next handoff,” Ortiz said as the lift lowered, “you can usually guess what a problem will feel like — and where it’s hiding.”