If you have invested in air disc brakes (ADBs) for your trucks, it’s important to know when you need to replace the caliper, and generally how to protect your investment in this braking technology. In this Tech Tip, Bendix supplies a few answers to these questions.
Know the signs of a bad caliper
“Regular ADB preventive maintenance includes examining and addressing issues that could lead to caliper damage and the possibility of a voided warranty,” said Mark Holley, Bendix director of marketing and customer solutions – wheel-end. “Don’t forget to inspect guide pin movement and take a look at tappets and boots for damage and contamination, for instance, along with checking seals and bushings. The potential for caliper damage is one reason Bendix recommends replacing ADB wear components with genuine replacement parts during a pad change – pad retainer, pad retention springs and shear adapters – and includes them in a complete friction replacement kit.”
In the shop, technicians conducting an annual wheel-off inspection should make sure the caliper slides freely and take a moment to examine the rotor. Look at the overall condition of the rotor and evaluate the color. If the rotor is a bright rusty-red color, then it could be an indicator to inspect the caliper more closely. For further information, refer to your air disc brake manufacturer’s Service Data Sheet.
Choose the right replacement
“It may seem obvious, but we can’t stress it enough: Not all calipers are the same, and the replacement you choose can have a huge impact on safety, performance and uptime,” Holley said.
If you’re exploring remanufactured calipers as a replacement option, Bendix advises to make sure to ask about the reman process. True remanufacturing adheres to the same rigorous processes and standards used to make OEM (original equipment manufacturer) calipers. Remanufacturing also always involves replacing or repairing a core’s components to bring the part up to OEM specs. Bendix remanufactured calipers, for instance, are produced on the same line used to produce OEM calipers, using OEM processes for assembly, the company says.
Once you’ve made your caliper choice, consistency is key: If you’re buying one, then make sure it’s a genuine caliper (either remanufactured by the OEM or service new) with the same design so you maintain all the features of your original brake. For example, the current Bendix adjuster manages the running clearance even better than the previous version. Non-genuine calipers will not have the same adjuster as your original brake, so you would lose that benefit.
Even minor differences in caliper construction and performance can cause brake pull or lead one brake to drag and overheat. For similar reasons, friction types also must match across the entire axle. In addition, because they may fit the wheel-end envelope differently, aftermarket calipers may interfere with suspension clearance, which impacts brake performance and can damage the suspension.
Other key points during new caliper installation include:
- Holding the caliper only on the exterior. To prevent injury, never insert your fingers between the caliper and carrier.
- Ensuring the newly installed caliper slides freely and can be moved by hand pressure only over the entire length of the guide pin arrangement.
- Making sure the hose routing arrangement doesn’t restrict the full travel of the caliper.
- Not overloading or damaging the adjuster. (Bendix brakes include a shear adapter that is designed to fail in the event of over-tightening, preventing damage to the mechanism itself.)
- Torquing bolts to proper spec and proper sequence.
Longer life cycles are another benefit of air disc brakes. The right part selection and maintenance practices will help you keep them operating safely and deliver lower total cost of ownership.
This Tech Tip was contributed by Bendix.