Bosch is a leading supplier of compound brake discs, which are increasingly used by vehicle manufacturers because of some of the important advantages they offer over cast iron discs.. 

The innovative lightweight design features a profiled aluminium disc chamber, combined with a high-carbon cast iron friction ring, securely fastened with stainless steel rivets. Tailored to meet the specifications of various vehicle models, these compound brake discs offer a blend of innovative materials and designs.  

The range of Bosch compound brake discs for Mercedes models has recently been extended. The design is based on the respective original equipment brake disc and the specially developed packaging protects both the brake disc and the anti-rust coating.

Compound brake discs feature various materials, binding methods and designs, depending on the vehicle model.

Advantages over standard cast iron brake discs include: 

• Lightweight component design results in lower fuel consumption and reduced CO 2 emissions.
• Reduced unsprung mass improves driving comfort and performance.
• Enhanced thermal capacity and heat conductivity reduces brake judder. 
• The friction ring is highly resistant to thermo-mechanical stresses.
• The friction ring and rotor hat are joined using a special method which further reduces undesired heat flow. This reduces warping and hot tears, as well as vibration and noise.

All Bosch compound brake discs are ECE R90 certified and therefore offer customers the same quality as OE components. Their material composition and tolerances are optimally adapted to the brake system of the designated applications. Bosch compound brake discs also come with the required studs and feature a high-quality zinc dust coating for excellent corrosion protection.

Bosch also highlights that it is important to remember the handling and installing of compound brake discs is different to normal discs. Compound brake discs are very sensitive, high-quality products, so special requirements and safety precautions are involved in the handling and installation of these components. For example;

• The hub seat must be clean, rust free and even. It should not be damaged in any way.
• When installing no assembly grease or copper paste should be used.
• When transporting a compound brake disc, always the person should use both hands, and grip the disc by the friction ring.
• The disc should not be lifted or carried by the disc chamber.
• Hammers and impact wrenches should not be used for installation. 
• When the wheels have been removed, steering motions should only be performed by rotating the steering wheel.
• The fitter should always use a torque wrench to tighten the screws of the compound brake discs.
• The fitter should tighten the wheel screws evenly in three stages to the torque specified for the vehicle. Bosch ecommends to: Evenly tighten the wheel screws crosswise using a torque wrench, max. 30% of the rated torque specified by the vehicle manufacturer.Tighten crosswise to 60% of the rated torque specified by the vehicle manufacturer. Tighten crosswise to 100% of the rated torque specified by the vehicle manufacturer.

After repair, the brake system should be bedded if possible. Vehicle manufacturer’s installation, assembly and safety instructions should also be followed. 

The Bosch Technical Bulletin on compound brake discs can be downloaded here.