Be careful when replacing brake discs. If the brake disc reaches a thickness below the defined minimum thickness, it must be replaced. Before installing the brake disc, clean the hub thoroughly. It is recommended to tighten the mounting screws to the torque specified by the vehicle manufacturer.
If the brake disc reaches a thickness below the defined minimum thickness, it must be replaced. • ZF Aftermarket improves road safety thanks to the highest quality of original parts • The TRW brake range complies with ECE R90 regulations
• ZF Aftermarket experts provide tips on replacing brake discs
As a leading global supplier of automotive parts, ZF offers one of the most comprehensive suites of safety technologies on the market. It includes: sensors, braking, steering and drive systems, airbags and electronic control units. By translating the quality of original parts into the aftermarket, ZF Aftermarket actively supports road safety. The company, as a specialist in the production and distribution of spare parts, was directly involved in the creation of the ECE R90 regulations. The market has therefore welcomed the news that, in addition to the production of brake pads and shoes, all brake discs and drums manufactured and sold throughout Europe for passenger cars, vans and trucks must now meet the minimum standards set out in the ECE R90 regulations. To meet these standards, parts must pass a series of tests and achieve near original equipment levels. As the owner of the TRW brand, ZF Aftermarket is proud to admit that the specification of brake discs dedicated to commercial vehicles exceeds the ECE R90 standards. The following article contains valuable tips for professional replacement of brake discs.
Brake discs are subject to very high mechanical and thermal loads. This is compounded by environmental factors such as water, dirt and gravel on the roads, all of which further impact wear and tear. Due to the fact that brake discs are among the most critical vehicle components in terms of safety, ZF Aftermarket experts recommend that only trained and authorized mechanics install the components. It is also important to follow the manufacturer's instructions regarding vehicle repair.
Before installing the brake disc, clean the hub thoroughly. (photo no. 1)
When the brake disc reaches the wear limit, i.e. the minimum thickness specified by the manufacturer, it must be replaced (photo 1). Before removing the brake disc, compare it with a new one. In addition to the correct part number, make sure you have all the components needed to install the brake disc to the wheel hub, i.e. new bolts, wedges and grease, as well as the appropriate tools needed for proper replacement.
The vehicle must be safely raised and the wheel removed - after disconnecting the ABS system, brake pad wear indicator and removing the brake cylinder, the brake pistons must be mechanically adjusted. To do this, remove the cap and turn the adapter underneath it counterclockwise. The pistons will then expose the brake pad inside. The "starting torque" of the overload clutch in the governor will produce a "click" sound.
Now you can remove the cotter pin, securing pin and mounting springs together with the brake pads. Once the screws securing the brake caliper yoke have been removed, it can be removed completely.
It is recommended to tighten the mounting screws to the torque specified by the vehicle manufacturer. Note: The following process may vary depending on the braking system and vehicle manufacturer.
To remove the hub and the attached brake disc, first remove the axle nut cover and the nut itself. Place the removed hub and brake disc on a stable work surface. The ABS ring can now be removed and all the connecting screws between the hub and the brake disc can be loosened and removed. The brake disc can be removed from the hub using a hydraulic press. Before installing a new brake disc, the contact surfaces on the hub should be thoroughly cleaned - they should also be free from corrosion. Use a new set of screws to attach the new brake disc to the hub (photo 2).
Never reuse used brake pads! In the next step, the new ABS ring is mounted on the wheel hub. The hub can be reattached to the axle and secured with a nut. Tighten the axle nut to the specified torque and install the cover. Before reinstalling the brake caliper, it is essential to clean the brake disc with TRW's specially developed cleaning agent. The next step is to install new TRW brake pads directly to the brake caliper after installing the positioning springs.
The mounting bolts should be tightened to the torque specified by the vehicle manufacturer. Never modify the brake pads at this stage. Grinding or mounting backwards may cause mechanical or thermal overload and thus increase wear. This may cause unwanted noise or sticking of the brake caliper guides, thus reducing braking effectiveness. Therefore, under no circumstances should any changes be made to the braking system!
Now you can install the brake cylinder and connect the cables.
Final adjustment is particularly important to ensure long-term and reliable operation. The adjustment process should be carried out in accordance with the vehicle manufacturer's specifications (photo 3):
• Turn the adjuster clockwise until the pads touch the brake rotor. Do not turn the regulator too far!
• Then turn the regulator back 3-4 clicks.
After applying and releasing the brake, it must be possible to rotate the wheel hub by hand. Then it remains to mount the wheel, center it and secure it by tightening it to the torque specified by the manufacturer. At the end of replacing the brake disc, it is especially important to test the parts on a brake test stand and perform a test drive.
Using original parts, developed and manufactured by experts, is of paramount importance for vehicle safety. ZF Aftermarket contributes to this with its extensive TRW "Corner Module" product range for steering, braking and suspension components.
