MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
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This guide provides instructions on replacing the rear brake pads on a Mercedes-Benz W209 CLK350 2006-2009.
Watch: Mercedes-Benz Rear Brake Pad Replacement Guide
These instructions apply to the following Mercedes-Benz W209 CLK models.
- 209.456 Mercedes-Benz CLK350 2006-2008 w/ Sport Package
- 209.356 Mercedes-Benz CLK350 2006-2008 w/ Sport Package
- 209.456 Mercedes-Benz CLK350 2009
- 209.356 Mercedes-Benz CLK350 2009
Tools Required
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Jack Stands: Best Selling Jack Stands List |
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Hammer. Yes, you will need one. |
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Pin Remover Removal Extractor Tool |
Parts Required
- W209 Rear Brake pads. Ceramic Recommended 003 420 27 20 0034202720
- W209 Rear Brake Pad Wear sensors.
- Pad sets are chassis specific, and the same number turns up on guides for several Mercedes models, so have the rear pad set looked up against your own VIN at a dealer parts desk before you order.
- Brake pad anti-squeal grease.
- Rotors (if you plan on replacing them).
How to change/replace rear brake pads on your CLK350 W209
- With the wheels still on the ground, slacken the rear lug bolts. Raise the car at its jacking point, rest it on jack stands, and chock the wheels at the front. The parking brake stays off for this one. It acts through the rear wheels you are about to dismantle, so leaving it applied holds the hub and makes the caliper harder to work on rather than safer.
- Open the hood and remove the cap from the brake fluid reservoir. This will allow the brake fluid to return to the reservoir when you press the pistons into the brake caliper. Note the location on the right top corner marked with “Brake Fluid”.
Location of power steering fluid, coolant, brake fluid, and windshield washer. - Remove the rear wheels from your Mercedes-Benz CLK 350 W209.
- Remove the brake pad wear sensor from the right brake pad.
- Use a hammer to remove the pin that holds the brake pads. As you extract the retaining pin, be careful not to hit the brake heat shield. If you hit the shield, you may bend it and cause it to make noise when you drive.
- Ease the caliper piston back into its bore. A dedicated piston press, or failing that a wide flat bar, spreads the force across the piston face. If a screwdriver is all you have, let it bear on the old pad and keep it clear of the rubber boot sealing the piston. Tear that boot and water gets into the bore, which becomes a seized caliper a few months later.
- Remove the old brake pads and clean the area where the brake pads make contact with the caliper.
- Install the new brake pads. Apply brake grease to the pad backing and the points where it sits against the caliper, and nowhere else. Friction material and rotor faces stay dry. Install the retaining pin. Make sure to align the brake pads and install the pin by hammering it in.
- Install the wheel and lower the car. Make sure to tighten the brake fluid reservoir cap.
What to do before the car leaves the driveway
Get the pedal firm again first. Winding the pistons back leaves a gap between pad and rotor, and the pedal has to take that gap up before there are any brakes at all. With the ignition off, press the pedal repeatedly. The first strokes feel long and empty; after several it should go hard and stay hard. Start the engine and confirm it still feels right. That is a minute of work and it is the difference between stopping at the end of the street and not.
Then the fluid and the fasteners. With the cap back on, look at the level in the reservoir, because forcing the pistons home drives fluid back up the line and can leave it above the mark. Start the lug bolts by hand, tighten them in a star pattern, and finish to the torque figure your manual or the dealer gives rather than by feel.
Treat the first few miles as part of the job. New pads need a little use before the friction layer settles against the rotor, so allow extra distance, keep the stops gentle, and avoid one heavy brake from speed. If the pedal is still travelling further than it used to once you have done that, something needs looking at before you keep driving.
Before you buy parts, scan every control module, not just the engine. It shows the root fault behind the warning lights and tells you whether the problem is still active. See how to do a full health check.
