TESTIMONIAL:
When I attempted to replace the front brake pads on a 2001 Mercedes S430, I discovered that my old Piston Reset Tool (the one everyone has in their garage, sold everywhere under different brands for less than $10) just could not do the job. This is because the S430, like many other cars, has Dual Piston, Fixed Caliper brakes, which require a different Reset Tool (sometimes referred to as a Brake Pad Spreader). When I went to Pep Boys, the salesman told me that fixed calipers are a problem, and he did not have the tool for the job. I went to an independent parts store, which had a tool that had been hanging on their wall since 1979 (it looked like a miniature scissors jack with a long screw), but it could not have been inserted where it needed to be. NAPA had a catalog with a picture of something with a pistol grip on it that looked like it may or may not have worked. The Mercedes dealer can order a tool (MB # 000 589 52 43 00) for $160 that looks like it could be used 1,000 times before it would come close to breaking or wearing out, which would be overkill; besides, it is huge and would take up too much room in my tool cabinet.
Bottom line: I had to buy a tool, and nobody stocks one like this one, so I had to order something from somebody. I found the item number #MKBRK-J for a very low price, and could see from the picture that it should work, so I ordered it. I'm glad I did, it arrived on time and worked perfectly!
Procedure was simple: I took the cap off of the master cylinder under the hood, then jacked up the car and removed the wheels. The calipers remained bolted to the car throughout the procedure (of course, if I was replacing the rotors also, I think I would have had to remove the calipers). After removing the retaining pin and spring from behind the pads, I inserted the Reset Tool arms between the small exposed edges of the backing plates on the brake pads. Then I turned the handle on the tool and the arms pushed away from each other and started pushing the brake pads away from the rotor. Once there was more space I put the arms of the tool against the face of the pads themselves and pushed the pads (and pistons) all the way back. The tools job was done; I then slid the old pads out, slid the now ones in, reinstalled the spring and pins and I was done (after checking the fluid level and putting the cap back on the master cylinder). I feel that I did receive a useful tool which does the job and should last a DIY-er a lifetime. It does not take up too much space in the tool box, and was also the least expensive option I found!
Steve M
Pennsylvania