Mercedes-Benz bulletin LI42.10-P-063502

Complaint Noises/ squealing from the service brake in various driving situations and ambient conditions. Cause Frictional vibrations Remedy The intent of this document is to reduce noise from high performance AMG brakes. AMG brakes are designed for performance under high load and in certain scenarios, can emit noise. Some scenarios are normal and some are induced by driving style like those listed below: • Driving style such as two footed driving where the pad might be in constant contact with the rotor. • Brake pressure and application style (stop‑and‑go traffic with consistent light brake pressure “riding brakes” where the brakes cannot cool sufficiently between applications). This can cause the brake pads to glaze and have a smooth/glassy surface which can induce noise. • When ambient temperatures rise during summer peak and during cooling and cold winter months. 1. Beginning Diagnostics: a) Check whether the complaint can be reproduced and at which axle or side the noises occur (ideally together with the customer while driving). b) Check the affected system for component wear, mechanical damage or localized overheating damage. Replace damaged components as necessary. c) Assess condition of brake rotors and pads per WIS and visually (i.e. long periods of stagnation, etc...). d) Clean brake components free of brake dust and debris. d) Secure vehicle on a lift. 1. Start the engine and depress the brake pedal 3‑4 times. 2. Check each wheel to see if they turn freely by hand. 3. If a wheel is not turning freely by hand, this needs to be addressed prior to re‑assessing the noise concern. e) Check whether, apart from this document, an additional document exists for the specific model in question, and if so, work through it and then continue. 2. Specific Axle Work: NOTE: If the brake pad has a metal backing plate, there is no need to affix the adhesive film. Continue with applying chamfer and Molykote as instructed below. IMPORTANT: Be absolutely certain to not allow paste between friction surfaces of the pad and disc! a) If the noises are coming from the front axle. 1. Remove brake linings of front axle. 2. Clean all contact points on brake lining backing plate, including the brake lining guide pins and brake caliper/carrier. 3. Clean bonding surface (where pistons contact back of brake pad). Apply adhesive film to the backplate of the piston‑side brake lining

Owners of the 150 model years this bulletin names have filed 4,253 complaints with NHTSA since 2015. 172 of them name Service Brakes — the same broad component group this bulletin is filed under. NHTSA groups complaints coarsely, so that means the same area of the vehicle, not necessarily the same fault.

On the 2016 Mercedes-Benz GLC-Class, the 23 owners who gave an odometer reading for Service Brakes reported it at a median of 6,000 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.