It’s no secret that a highly effective way to increase any vehicle’s performance is to decrease weight (or ‘add lightness’ in the words of Lotus founder Colin Chapman). However, when it comes to vehicle dynamics not all kilograms (lbs) are equal. Saving weight from some areas of the vehicle has a far greater impact than others.
One particularly advantageous component to reduce in weight is the brake rotor, which we explain in this article.
A lighter vehicle will accelerate harder, change direction better and crucially, require less energy when doing all of the above. When it comes to racing cars, reducing weight is all about achieving better lap times, but if we come at this one from a different angle for a second and consider an electric vehicle (EV) such as Tesla’s Model S or Model X, less energy expenditure actually means increased range.
If we dive into the physics for a moment, the weight of a vehicle can be split into 2 categories; sprung weight and un-sprung weight. The sprung weight is the weight suspended by the coil springs (body, seats, occupants, luggage etc.). The un-sprung weight is the weight not supported by the suspension (wheels, tyres, wishbones, brake calipers, brake rotors etc.).
The un-sprung weight can be split down further still, into static un-sprung weight and rotational un-sprung weight. The rotational part is the important bit here.
Of the un-sprung components, the wheel rim, tyre and brake rotor are all rotating (there are also a few other components that contribute to the un-sprung rotational mass such as the driveshaft, but since these have a negligible effect we’ll disregard these for now).
All objects with a mass have inertia. Quite simply, inertia is how resistant an object is to changing its state of motion. The higher the mass the higher the inertia. However, rotating masses have an additional component, known as rotational inertia. When you get a mass spinning fast it wants to carry on doing what it’s doing, it resists any change in motion. Anyone trying out one of those gyroscopic wrist exerciser balls will have felt first hand (no pun intended) how much more difficult it is to move a mass with rotational inertia than a mass that is static (i.e. the ball puts up way less of a fight when the gyroscope stops).
Exactly the same principle is happening with the brake rotor’s mass when the vehicle is moving. The brake rotor has rotational inertia which means it fights back against manoeuvres such as accelerating, cornering and braking.
Whilst all Tesla models feature lightweight alloy wheels as standard (for this exact same reason of reducing the rotational un-spring weight) and even come with lightweight aluminium brake calipers, they are also fitted with heavy 1pc cast-iron brake rotors, simply due to cost. With electric vehicles being significantly more expensive to produce than conventional internal combustion engine vehicles, it’s perhaps no surprise the accountants won on this one. I guess Elon’s gotta fund that space program somehow. Alas, Tesla models are fitted with a basic 1pc design brake rotor which is significantly less expensive to produce but comes at a heavy price in terms of vehicle dynamics and range.
EBC Racings’ 2pc fully-floating FRONT rotors are 3.5kg lighter per piece, equating to a 7kg (15lbs) weight saving across the front axle.
This is usually the point where people say “yeah but how much difference is 7kg (15lbs) weight reduction really going to make on a vehicle weighing 2,100kg (4,600lbs)?”. They’d have a point, were they not overlooking 2 crucial elements; the brake rotor weight is un-sprung and rotational.
Studies show that shedding un-sprung static weight is equivalent to saving between 2x and 5x that figure from the sprung mass, but even more impressive than that, shedding un-sprung rotational weight has been shown to be equivalent to a 10 – 15x weight saving from the sprung mass … This is backed up by independent testing carried out by a number of performance wheel rim manufacturers, the information is readily available out there people should you wish to read up further!
This means that our 7kg (15lbs) weight saving offered by EBC’s 2pc floating brake rotor is actually equivalent to removing between 70kg (154lbs) – 105kg (231lbs) from the sprung mass of the vehicle … Or to put it another way, an adult passenger!
Doing the math, this equates to a reduction in energy consumption of approximately 4-6%, or a 10-15 mile increase in range … On every single full charge.*
Knowing you’ve got an extra 10-15 miles range added to every journey, I’m sure you’ll agree, is a pretty handy increase and helps to address the ‘range anxiety’ concerns felt by some Tesla owners.
Better still, no modifications whatsoever are required to fit the EBC 2pc floating brake rotors. They are a direct like-for-like replacement for the stock rotors and fitting can be completed in 1-1.5 hours with basic tools.
EBC’s 2pc fully-floating rotors also offer several other benefits over stock rotors, or other 2pc rotors available on the marketplace:
- Black hard-anodised aluminium hub looks great and will not rust
- Rotor vanes are coated in an anti-rust black surface treatment
- ‘Fully-floating’ design means the rotor will not warp under even the most severe braking. This product is as capable on the racetrack as it is on the highway.
- Stainless-steel bobbins ensure the rotor continues to ‘float’ freely over its entire lifetime (unlike many competitor 2pc rotors which use steel bobbins that seize up over time and prevent the rotor from floating).
- 48-curved vanes allow for highly effective rotor cooling, reducing brake operating temperatures and prolonging the onset of brake fade.
- Rotor is cast from a high grade G3500 alloy which has increased wear resistance.
- Oh yeah, and did we also mention they look absolutely fantastic behind the wheel, giving an already elegantly styled car some added aggression?
For pricing please contact your local EBC distributor: https://ebcbrakes.com/where-to-buy-ebc-products/
Fitting new rotors also requires the fitment of new pads, which is why these rotors are also available as a 2pc rotor + pad kit which saves 50% off the pad’s RRP.
MATCHING REAR LIGHTWEIGHT 2PC ROTOR UPGRADE COMING SOON
*Energy consumption may vary depending on driving style and conditions. The figures quoted are calculated based on fundamental vehicle dynamic principles and EBC Brakes makes no guarantees as to the expected increase in range achieved when using this product.