Following a supply agreement with SGL Carbon, Audi are introducing carbon fibre reinforced ceramic brakes on the new Audi A8.
Audi is one of very few mainstream automotive manufacturers incorporating the new braking technology in a series production model, the new 12-cylinder A8.
Audi claim that the material will quadruple brake service life compared to conventional steel discs, and offer “outstanding braking power”, even when the car is being driven to its limit, as well as improved resistance to fading.
The commercial introduction of reinforced ceramic brakes for the Audi follows an agreement that Audi signed with German SGL Carbon, manufacturer of carbon fibre materials for industrial and aerospace applications in June which were made in the preparation of the availability of the A8 from this week.
An additional element of the agreement between Audi and SGL Carbon is a possible joint investment in mass production resulting from the development agreement. This could also take place within the framework of a joint venture. A decision on this will be made at a later date. In the meantime, Audi will be acquiring the carbon-ceramic brake disks in the context of a long-term supply agreement.
The brake discs are made from carbon fibre reinforced ceramic, a material which is more widely used in the field of aeronautical and aerospace engineering. The ceramic material’s composite structure is made up firstly of silicon carbide, a hard and abrasion-resistant base material with a crystal structure similar to that of diamond. The high-strength carbon fibres which are then embedded in this base material are able to absorb the stresses that occur in it.
Audi state that the material offers a whole spectrum of benefits with the most visually apparent of these being the insusceptibility to corrosion with no signs of rust formation will be found on a ceramic brake disc.
The technical benefits have an even greater impact: first, there is the weight-saving of some five kilograms, or around 50 percent, per wheel. The result is a clear reduction in the unsprung masses at the wheels, which Audi claim will make the ride more comfortable.
The high abrasion resistance of the ceramic discs means a service life of up to 300,000 kilometres under standard day-to-day operating conditions, four times greater than that expected of a steel disc. Plus, the degree of wear over the brake’s service life is a mere 0.5 millimetres.
Ceramic discs with a diameter of 380 millimetres are fitted at the front to partner 19-inch wheels. The discs at the rear measure 356 millimetres across. The ceramic brake disc ring is bolted by means of ten flexible connector elements to a stainless-steel bowl which in turn links it to the wheel hub. The elaborate cooling duct geometry used for the internally ventilated brake disc ensures optimum brake disc cooling. 6-piston monoblock aluminium callipers from Brembo at the front brakes and sliding-calliper brakes at the rear guarantee a vice-like grip on the discs. Electromechanical operation of the parking brake continues to make up part of standard specification as it does on all the other A8 models.
The new ceramic brake will be available to order as an option for the A8 W12 and A8 L W12 quattro 12-cylinder models from July 2005.
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