For the past 50 years, Brembo has supplied disc braking systems for passenger cars, motorcycles, commercial vehicles and racing cars, serving both the OE and aftermarket. In this interview, Matthew Beecham talked with executives of Brembo about the forces driving innovation in the brakes arena.

just-auto: What are the forces driving innovation in foundation braking for passenger cars?

Brembo: Basically the forces driving innovation in foundation braking are:

  • weight reduction;
  • residual torque reduction;
  • NVH continuous improvements;
  • performances;
  • style;
  • and mechatronics.

j-a: For reasons of low cost and ease of maintenance, I guess the developing regions still use drum brakes. Is that correct?

Brembo: It is correct for the commercial vehicle market, not for the passenger car market.

j-a: I guess reducing stopping distances and weight reduction will always be a priority when it comes to design and development of braking systems, yet to what extent is improving the brake feel important?

Brembo: Yes, reducing stopping distances and weight reduction will always be a priority and it depends on the segment: the radical weight reduction and shortest stopping distances (despite comfort) are implemented on sports cars. However, [we should] take into account that the stopping distance is not directly correlated to calliper and discs. What we have to do, as a brake manufacturer, is to design a brake system that is able to lock the wheels in every condition; when the wheels are locked the stopping distance is basically up to the ABS system and tyres.

j-a: I guess given the move toward standard fitment of ABS on new vehicles in Europe, drum brakes have all but disappeared as new vehicle models replace outgoing ones and due to the fact that ABS brake systems require discs on every wheel. Is that correct?

Brembo: It is correct that new vehicles in the EU have discs on the front axle, but it is not correct that ABS needs discs on every wheel, ABS can work also with drums.

j-a: Could you comment on the extent to which disc brakes superseded drum brakes in Europe?

Brembo: We think that the drum solution remains on applications constrained by very small wheel size and cost issues.

j-a: How does that situation (disc brake versus drum brakes) in Europe compare to North America?

Brembo: Similar situation with passenger cars, i.e. more drum brakes for commercial vehicles.

j-a: In what ways has the growing use of electronic control affected braking hardware?

Brembo: Basically we have to consider during the design process the possibility of having on the rear axle the same level of pressure we have on the front (braking in reverse direction). This situation was not allowed without electronic control.

j-a: Could you sum up the latest advances in friction material in terms of composition and organics?

Brembo: [Our] friction material development has always taken into account pollution and safety. Asbestos in the early 1990s, lead, antimonium [anti-friction alloys] in the 2000s and now copper, are the materials completely or partially eliminated on pads.

j-a: In what ways have carbon-ceramic brakes advanced over the past few years? 

Brembo: Starting from super cars (i.e. Ferrari ENZO, McLaren SLR), now carbon-ceramics brakes are available on cars coming from lower segment (i.e. Audi S8, Mercedes SL). This means improvement on performance and NVH.

j-a: In terms of brake disc materials, in what ways have these materials advanced over the past five years? 

Brembo: The cast iron development was  achieved in terms of improving quality and reducing cost. Some improvements were also done  to improve mechanical resistance and NVH behaviour.

j-a: Due to economics, I guess cast iron will remain the material of choice for the foreseeable future?

Brembo: We think that we have proven that carboceramic discs represent a very promising alternative, but we do not see the cost of this solution becoming appealing in the next few years, especially for volume applications.
 
j-a: I guess there is a practical limit to braking performance, set by the ability of the tyre contact patches to transmit the forces involved without sliding. However, I guess advances in tyre design mean that limit is now potentially very high, at least on dry road surfaces. Is that throwing the onus very much back to the braking system developers? How will tomorrow’s brakes perform?

Brembo: The braking system design will follow the future adherence limit tyre-road. Anyway the braking system is yet designed for more than the torque needed to stop the vehicle, so even if the tyre adherence limit will increase there will not be any problem.

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