In order the reduce the brake dust from the rear brakes on my 2012 R172, I replaced the rear pads with low dust metallic pads this morning.
Before any work can be done on the rear brakes the electronic parking brake must be put in 'Fitting Position' or 'Assembly Position' using the car's service menu. If this is not done, the rear brake cylinder piston cannot be pushed back in at all and new brake pads cannot be fitted.
To enable 'Fitting Position' mode you have to enter the service menu on the instrument panel. To do this follow these steps:
1. Make sure the hood (bonnet) is closed.
2. Release the Parking Brake if it is set (you will get an error later on in the process if this is not done).
3. Turn the key to position 1.
4. On the right side of the steering wheel, Press and Hold the right (End Call) telephone button, the left (Accept Call) telephone button AND the OK button on the left side of the steering wheel all at the same for around 5 seconds.
5. The workshop menu should appear.
6. Scroll down to 'Pad Replacement' using the arrow buttons on the steering wheel and press Ok.
7. The confirmation 'Move to Fitting Position' should appear.
8. Confirm again by using OK.
9. NOTE: do not try to enable the Parking Brake or press the brake pedal while completing this procedure.
10. A message should appear letting you know the procedure is complete and that the motor for the parking brake has been retracted.
11. Turn off the ignition and remove the key.
While in 'Fitting Position' the Parking Brake failure light will be displayed on the IP.
You can now change the rear brake pads in the normal manner (see attached PDF for details). Thanks to JudgeMing for providing this document!
After all the steps of the rear brake pad replacement or rear brake repair have been completed:
1. Turn the ignition back to position 1
2. The message Fitting Position reached. To Exit Fitting Position: OK' - should appear.
3. Press OK to exit the procedure and to reset the parking brake motor.
Changing the rear brakes is rather easy on this car. In order to push in the brake caliper piston so that it will clear the new brake pads, all you need is a standard brake cylinder piston compression tool (a big C-Clamp will work, too).
The last image is of the tool I used to compress the brake caliper piston.
BTW, I used Centric 104.16460 - Posi Quiet Premium Metallic Rear Brake Pads with Shims and Hardware. I wanted ceramic pads but had to settle for these. They were cheap, $35 including shipping. I'll post a follow up when I find if they really do reduce the brake dust.
Follow up (4/21/2015): The Centric 104.16460 - Posi Quiet Premium Metallic Rear Brake Pads did not reduce brake dust at all as compared to the original pads.
Follow up #2
(10/5/2015): I found the TRW TPC1646 Premium Ceramic Rear Disc Brake Pad Set
for the R172 on Amazon, http://www.amazon.com/gp/product/B00...ilpage_o04_s00
After several hundred miles of city driving, my rear wheels are now just as brake dust free as the front wheels are.
Ont thing to note about the TRW set is that they did not come with any brake hardware at all except for the pads. The Amazon product description says that it includes the hardware but in my case it did not. Since I got the last set on Amazon and it would take 2 - 4 weeks before they were in stock again, I decided to just use the set I got. Plus my rear brakes hardware was almost new from the previous installation of the Centric pads just 1,500 miles ago.
But if your car has higher mileage this may be a problem for you.