When you upgrade your vehicle’s braking system, it’s important to take brake torque into consideration. If the brake torque is too high or too low, your vehicle’s braking system won’t perform the way you want it to. To keep your vehicle’s braking performance where you want it after the upgrade, make sure the brake torque is within the correct parameters.
What Is Brake Torque?
Brake torque is a way to measure the pressure exerted on the brake shoes and/or the rotors when slowing down or stopping the rotation of the wheels. A vehicle needs brake torque to come to a stop. When you apply your brakes, the brake calipers press the pads against the brake rotors. This stops or slows down the rotors. When that happens, the axle and wheels stop or slow down accordingly. The amount of force used to slow the rotors is called brake torque.
If your vehicle doesn’t have enough brake torque, it cannot stop as well as it could. If your vehicle has too much brake torque, it has too much stopping power. Ironically, the vehicle doesn’t stop as well as it should, either.
The factors that determine the brake torque are:
- The effective radius (the distance between the brake caliper/brake pad assembly and the hub center)
- The size of the brake pads
- The force exerted by the caliper
There needs to be a good balance between all three factors to optimize the vehicle’s braking power.
If the caliper/brake pad assembly is too big for the rotor, the brake torque is too high. In that case, the tires will want to lock up, and the brakes will be grabby. This causes the tires to start skidding instead of effectively rolling to a stop. Your vehicle’s advanced driving aid system may kick in and possibly make the situation worse. If the caliper/brake pad assembly is too small for the rotor, the brake torque is too low. In that case, the brake pads can’t stop the rotor from turning or will take a long time to stop the rotor. This greatly increases the vehicle’s stopping distance, which is quite dangerous.
Is Brake Torque The Same As Engine Braking And Torque Specs?
Brake torque is one of the most misunderstood terms in the field of vehicle dynamics. A lot of people have no idea what it actually is. Some people also confuse brake torque with:
- Engine braking
- Torque specs for nuts and bolts in the brake system
Brake torque is actually completely different. It’s not interchangeable with these two terms. Like we mentioned earlier, brake torque is the force necessary to stop the vehicle safely and quickly.
How to Calculate Brake Torque
It is possible to measure brake torque directly. Engineers do this when they are designing brake systems. They take several factors into account such as:
- Speed of the vehicle
- Tire pressure
- Throttle response
- Steering angle
- Steering system
Engineers use the following formula to calculate brake torque, :
Brake torque = (the force exerted by the caliper) * (the effective radius of the system)
This formula determines the maximum braking force that can be exerted by a single wheel.
It would be very difficult for most people to calculate brake torque. But it is a helpful concept to understand. If you find that your brakes are grabby, your brake torque may be too high. You can alter this by several different means, but a pad change to something less aggressive is a likely first step. If you find that your brake torque is too low, you have several options. You could upgrade to a better pad, or move to a bigger caliper/brake pad assembly. If you have questions about all of this, we’re happy to help.