GL450 Pedal Softness & brake "rattling" sound after front pad & rotor replacement
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2012 GL450
GL450 Pedal Softness & brake "rattling" sound after front pad & rotor replacement
I replaced the front brake pads & rotors on my 2012 GL450. I used Mercedes OEM rotors, and Akebono pads. Following the directions of several tutorials, I compressed the caliper pistons back into the caliper without opening the bleeder valve (thereby pushing the fluid all the way into the master cylinder). Following the replacement, the pedal was extremely soft. I mean, it goes all the way to the floor, and I could hear what sounds like air hissing from the pedal. It's like I have air in the lines, but there is no way that air could have gotten in there. But just to be sure, I performed a brake fluid flush on all four circuits. After that, the pedal firmed up very slightly. But now, when I drive it, there is a rattling / banging sound coming from the front brakes when I coast in the vehicle. The banging stops when I apply the brakes, and stops when I accelerate. But as soon as I let off the gas and the vehicle weight transfers forward, there's the banging sound (until I apply the brakes).
Does anyone have any idea what in the world is going on here? Both the banging and the soft pedal.
Does anyone have any idea what in the world is going on here? Both the banging and the soft pedal.
Senior Member
Joined: May 2013
Posts: 437
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From: Espoo, Finland
2012 GL 350
Banging is usually a result of a missing anti-rattle clip or potentially a loose caliper retention bolt.
Softness in the pedal even after a brake flush could be many things. If it were me I would:
1. Inspect all the brake lines to ensure they are not cracked/damaged (did you hang the calipers from the lines or from a wire?)
2. Inspect the brake master cylinder (did you use a pressure bleeder or the pump method?) for leaks
3. Recheck all your fasteners to ensure they are tight and ensure all your clips are in place.
4. Ensure that your caliper bleed screws are tightened properly (but not too tight!) It's easy to get scared to apply too much torque and inadvertently leave them loose allowing air in.
5. Re-bleed the brakes and see if it improves.
Softness in the pedal even after a brake flush could be many things. If it were me I would:
1. Inspect all the brake lines to ensure they are not cracked/damaged (did you hang the calipers from the lines or from a wire?)
2. Inspect the brake master cylinder (did you use a pressure bleeder or the pump method?) for leaks
3. Recheck all your fasteners to ensure they are tight and ensure all your clips are in place.
4. Ensure that your caliper bleed screws are tightened properly (but not too tight!) It's easy to get scared to apply too much torque and inadvertently leave them loose allowing air in.
5. Re-bleed the brakes and see if it improves.
