Pulse, Grinding, Scraping Noise from Brakes, Uneven Front Brake Pad Wear - 2014-2019 Cadillac Chevrolet & GMC

During a brake inspection, some complaints of uneven front brake pad wear have been reported. The vehicle may have low mileage, typically around 16,093 km (10.000 miles) and the inner pad on either the front left, or right side, may be worn out.

•   Inboard to outboard brake pad wear difference of 3 mm (0.118 in) or greater for ‘normal’ highway driving (no heavy loads, without trailer towing, without frequent elevation changes).

•   Inboard to outboard brake pad wear difference of 6 mm (0.236 in) or greater for the following driving conditions: heavy city driving, frequent elevation changes, frequent trailer towing, heavy loads.

•   Left to right inboard to inboard or left to right outboard to outboard brake pad wear difference of 3 mm (0.118 in) or greater for either driving condition.

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Shown above is an example from one vehicle with uneven wear. Photo 1 is of the left front brake pads where the inner pad is worn completely out, while the outer pad still has plenty of pad life. Photo 2 is from the same vehicle, but of the right front inner and outer brake pads, which both have plenty of pad material left.

Important: Remember the following when servicing/inspecting the front brake systems:

–  DO NOT use any air tools to remove or install the brake caliper bolts. Use hand tools ONLY.

–  Install an open end wrench to hold the caliper guide pin in line with the brake caliper while removing or installing the brake caliper bolt. DO NOT allow the open end wrench to come in contact with the brake caliper.

–  When compressing the caliper pistons, use large C-clamps over the top of the caliper housing and against the back of the outboard pad. Slowly tighten the C-clamps until the pistons are pushed completely into the caliper bores. Using this method will help determine if there is anything binding.

1.   Inspect and measure the brake pads thickness. Determine the type of driving the owner does and compare the measurements to the information listed above (3mm or 6mm).

•   If the pads are within specification, disregard this bulletin and perform a normal brake repair.

•   If the pads are out of specification, perform normal SI diagnostics to determine the cause of the concern (caliper piston binding, binding pads or guide pins in bracket, brake hose restriction, etc.

2.   After completing normal diagnostics, if a root cause for the uneven pad wear is not found, replace the front brake pads with the part number in the table below. Refer to the Brake Rotor Surface and Wear Inspection, in SI to determine if the brake rotor(s) require servicing or replacement. If the brake rotors require service due to excessive heat checking/blueing, it is recommended to replace the rotors rather than attempting to refinish the rotor(s) for this issue. Refer to the parts catalog for the correct O.E.M. rotor part number, which are Ferritic Nitro-Carburizing (FNC) rotors.

Note: The brake pad kit part number listed below is intended to be used together with the

O.E.M. brake rotors. If the rotors were previously replaced with part number 22950035 (NON-FNC), per the earlier version of PIT5377G, and the vehicle now requires brake rotors, refer to the parts catalog and replace both rotors with the O.E.M. brake rotors.

3.   After repairs and pad burnishing have been completed, test drive the vehicle for 32 – 48 km (20 – 30 miles). The test drive needs to be performed on an open road at cruising speeds 88.5 kph+ (55 mph+) where very little braking is actually performed.

4.   Immediately after returning from the test drive, lift the truck up on a hoist and spin both front wheels by hand, checking for a wheel that is hard to spin. If a wheel is hard to spin, it may be an indication of a brake drag.

5.   While the condition is present, perform normal SI diagnostics to determine the cause of the drag (caliper piston binding, binding pads or pins in the bracket, brake hose restriction, etc). Repair if necessary and re-evaluate the concern.

Number

22950036 (NON-FNC), per an earlier version of PIT5377G, then both front rotors need to be replaced with the PN

specified in the parts catalog