Front Disc Brake replacement
I believe this information must also be useful to most Mercedes C, CLK and SLK manufactured from year 1997 to maybe 2004. And if you have a Mercedes SLK R170 with a 320 engine the chassis are almost identical.
1, Removing the brake caliper:
First you lift car with a car jack, and do it in a safe way. And wear protective glasses and gloves.
Have enough space around the car, when you lift it it will move a bit side ways. Lock the handbrake and put blocks in front and back of the opposite wheels so the car can't move when lifted. Before you lift the car you can loosen the wheel nuts a bit, not more then a 1/4 turn.
Never work under the car with only the car jack hold up the car. Use a trestle support stand. Place it under the car according to the service manual says it's safe.
When got the wheel off, remove the spring that holds the brake caliper in position. You can remove it with a screwdriver that you put under were the arrows are and slightly bend it up. Hold the spring with your other hand so it don't fly away, protect your eyes.
There is one sensor on the brake caliper, the warning sensor when there is need to replace the pads. Be sure to not broke this cable, you can either disassemble it from the brake caliper or loosen the cable from the two holders. Then it will be long enough to put the brake caliper aside. On my car it's the front cable, but check carefully if it this also in the case of your car.
This is the lower cable holder.
Now you can lose the two bolts that holds the brake caliper. You must first remove the dust caps above them.
You need a 7 mm hex wrench. Standard are 6 mm or 8 mm, it could be a bit difficult to find a store that have it.
Here how the brake caliper bolts looks when removed. The brake caliper slide along these bolts, if they are rusty or have any damage you should replace them.
Before you remove the brake caliper you have to push back the hydraulic pistons. You can use a brake caliper tool. When you remove it, hang it in a steel wire above. Don't let it fall down, it can destroy the hydraulic hose or the electric wire.
If you want to learn more about brake calipers read here: