All that with a seemingly small weight reduction of 7 kg (15.4 lb).
EBC Brakes is now selling two-piece front brake rotors for both the Tesla Model S and the Model X. These new rotors are 3.5 kg (7.7 lb) lighter than the ones the Tesla EVs offer. The total 7 kg weight reduction would be enough to offer up to 15 miles more range. But how is that even possible, right?
Gallery: Can EBC Brake Rotors Help Increase Tesla Model S And Model X's Range?
EBC’s explanation for that is that the weight reduction happens inside the wheels. That implies the company is eliminating it in a crucial area: one that concentrates the cars’ unsprung mass. Unsprung and rotational, by the way.
The company says that studies show that reducing unsprung static weight is like saving two to five times the same mass on the sprung mass. In other words, if the 7 kg did not rotate, they would be equivalent to shedding up to 35 kg in the car.
But the fact is that rotors rotate, and rotational unsprung mass that is taken away from the vehicle is equivalent to eliminating 10 to 15 times that same mass from the sprung mass. In other words, the 7 kg on the rotors equals up to 105 kg of weight shedding on the body.
That is, according to the company, where the extra 15 mi of range can come from. Remember that these rotors are for the front wheels. If EBC develops rear rotors, the weight saving can be even more significant.
The company also reminds interested clients that the new rotors will demand new pads, but it does not mention if they are much lighter than the ones Tesla offers as standard. In the pads case, they are part of the unsprung static weight.
If these numbers are accurate – and EBC can prove them with a video, for example – we can imagine a whole line of customers getting in touch to have these new rotors. Especially those that miss the miles Tesla has suppressed with the 2019.16.1 and 2019.16.2 software updates.
EBC BRAKES RACING’S TWO-PIECE ROTORS IMPROVE RANGE ON TESLA’S MODEL S AND MODEL X
- Two-piece fully-floating rotors now available for Tesla’s range of large saloon and SUV electric vehicles
- Save 7kg of unsprung rotational mass across the front axle and increase vehicle range
- Direct replacement for stock rotors – no modifications required
IMPROVE BRAKING AND INCREASE RANGE
EBC Brakes Racing’s two-piece fully-floating front brake rotors are now available for Tesla’s range of Model S and Model X electric vehicles.
Utilising EBC’s decades of expertise in the art of performance braking, these flagship high-performance components offer several benefits over the stock rotors and other two-piece rotors available on the marketplace, including reduced unsprung weight and even an increase in vehicle range.
- ‘Fully-floating’ design means the rotor will not warp under even the most severe braking.
- Black hard-anodised aluminium hub looks great and will not rust.
- Street legal – 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.
- 48 curved vanes allow for highly effective rotor cooling, reducing brake operating temperatures and prolonging the onset of brake fade.
- Rotor vanes are coated in an anti-rust black surface treatment.
- Cast from a high-grade G3500 alloy which has increased wear resistance.
- Did we mention they look absolutely fantastic behind the wheel, giving an already elegantly-styled car some added aggression?
A LITTLE GOES A LONG WAY
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 equates to something completely different entirely: increased range.
EBC Brakes Racing’s two-piece fully-floating front rotors are 3.5kg lighter per piece, equating to a 7kg (15lb) weight saving across the front axle.
How much difference is 7kg really going to make on a 2,100kg car though, we hear you ask?
It’s important not to overlook two crucial elements as we answer this question: the brake rotor weight is unsprung AND rotational.
Studies show that shedding unsprung static weight is equivalent to saving between 2-5 times that figure from the sprung mass. But even more impressively, shedding unsprung rotational weight has been shown to be equivalent to a 10-15 times weight saving from the sprung mass (backed up by independent testing carried out by a number of performance wheel rim manufacturers).
This means that the aforementioned 7kg (15lb) weight saving is actually equivalent to removing between 70kg (154lb) and 105kg (231lb) from the sprung mass of the vehicle, or to put it another way, a full-sized adult passenger!
Doing the maths, the above weight reduction equates to a drop 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 of range added to every journey is an extremely handy increase that’s sure to help address the ‘range anxiety’ concerns felt by some Tesla owners on a daily basis.
Better still, no modifications whatsoever are required to fit these rotors. They are a direct like-for-like replacement for the stock items, and fitting can be completed in 1-1.5 hours with basic tools.
The weight of a vehicle can be split into two categories: sprung weight and unsprung weight. The sprung weight is the weight suspended by the coil springs (e.g. body, seats, occupants and luggage). The unsprung weight is the mass not supported by the suspension (e.g. wheels, tyres, wishbones, brake calipers and brake rotors).
The unsprung weight can be split down further still, into static unsprung weight and rotational unsprung weight. The rotational part is the important bit here.
Of the unsprung components, the wheel rim, tyre and brake rotor are all rotating.
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.
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 one-piece cast-iron brake rotors, simply due to cost constraints.
As electric vehicles are often significantly more expensive to produce than conventional internal combustion engine vehicles, it’s perhaps no surprise the accountants won this battle. Alas, Teslas are fitted with this relatively basic design of brake rotor which is significantly less expensive to produce but comes at a heavy price in terms of vehicle dynamics and range.
EBC BRAKES RACING
Formed in 2015 as a response to the ever-expanding track day and race car markets, EBC Brakes Racing is a sub-division of world-leader in the industry, EBC Brakes.
With modern vehicles becoming increasingly heavy, coupled with ever-higher power outputs, the demand placed on the braking system today is higher than ever. As such, EBC Brakes Racing was born: aiming to offer uncompromised braking products of the finest quality that offer unparalleled levels of performance.
Several million pounds has already been invested into the development of EBC Brakes Racing’s British-built range of products, which includes the likes of RP-1 pads, Apollo Big Brake Kits and fully-floating two-piece rotors.
EBC Brakes Racing provides car enthusiasts around the world with quality, UK-made parts at competitive prices, whilst staying true to its mantra of developing braking products that offer unparalleled levels of performance.
Part number: SG2FC2141
Currently available for the front axle only. Matching rear rotor upgrade coming soon.
Please note: fitting new rotors also requires the fitment of new pads.