Torque Converter
What is Torque?
In physics, torque (τ) is the rotational equivalent of linear force. It measures how much a force acting on an object causes that object to rotate.
Imagine using a wrench to tighten a bolt. The longer the wrench, the easier it is to turn. This is because Torque = Force × Distance.
- Force: How hard you push.
- Distance: The length of the wrench handle (from the bolt to your hand).
Why Mechanics Obsess Over Torque
Torque isn't just about tightness; it's about "Clamping Force." When you tighten a bolt on a car engine or wheel, you are slightly stretching the metal bolt. This stretch creates tension, holding the parts together.
If you apply too little torque, the bolt vibrates loose. If you apply too much torque, you stretch the metal past its elastic limit, causing it to snap or strip the threads.
Nm vs. Ft-Lbs (Metric vs. Imperial)
Just like distance and speed, the world is divided on torque units.
1. Newton Meters (Nm)
The standard metric unit used by almost all European and Asian car manufacturers (BMW, Toyota, VW). It represents a force of 1 Newton applied at the end of a 1-meter lever.
2. Foot-Pounds (ft-lb)
The standard US unit (Ford, Chevy). It represents 1 pound of force applied to a 1-foot lever.
Common Torque Specs
Here are typical values for common automotive parts to give you context.
| Part | Metric (Nm) | Imperial (ft-lb) |
|---|---|---|
| Spark Plugs | 20 - 30 Nm | 15 - 22 ft-lb |
| Oil Drain Plug | 30 - 40 Nm | 25 - 30 ft-lb |
| Wheel Lugs (Sedan) | 100 - 120 Nm | 75 - 90 ft-lb |
| Wheel Lugs (Truck) | 190 - 220 Nm | 140 - 165 ft-lb |
Using a Torque Wrench Properly
A torque wrench is a precision instrument, not a breaker bar.
- Don't Drop It: Impact can ruin the calibration.
- Unwind It: When storing a "Clicker" style wrench, always turn the handle setting back to zero. Leaving it compressed weakens the internal spring over time, making it inaccurate.
- Don't Double Click: Once you hear the "click," stop pulling. Pulling again applies extra torque above the setting.