Rear Brake Pad Set 0034202720 for Mercedes SLK Crossfire

Rear brake pad set 0034202720, FMSI number D779, measures 72.9 by 63.6 by 15.3 mm and fits the Teves rear calipers on the Mercedes SLK R170 and R171, the C-Class W202, S202, W203, S203 and CL203, the CLC, the CLK C208, A208, C209 and A209, the E-Class W124, S124, C124 and W210, the CL C140, the S-Class W140 and the Chrysler Crossfire, from 1991 to 2011.

Mercedes used two different rear pad shapes across this generation of cars and they look almost the same in a photograph, so the number matters more than the picture. The D779 pad is the narrower of the two: its friction footprint is a few millimetres smaller in both directions than the D873 pad, the backing plate ears are set at a different spacing, and it sits in a caliper with a slightly smaller piston. Fitting a D873 pad where a D779 belongs leaves the pad hanging on one ear, and forcing it in will crack the shim and jam the pad against the disc. Measuring the old pad, or reading the FMSI number off the back plate, is the only reliable way to order the right one.

How they fail. On the older W202, W124 and R170 cars the failure is usually seizure rather than wear: the pad ears rust into the bracket, the pad stops sliding, and one face wears down to metal while the other stays thick. The owner notices a scrape that turns into a grind, a rear wheel that is hotter than the others after a drive, and a handbrake that will not hold because the drum inside the disc has been cooked. On the Crossfire, which uses the SLK R170 rear axle, the same pads wear faster because the car is heavier on the rear than the SLK it was derived from. A pad that has separated from its backing plate is a scrap part, not a rebuildable one.

Fitting notes. Check the number on the old pad before the new set is unpacked. Open the reservoir cap, push the piston back with a proper wind back tool, and hang the caliper so the hose is not under tension. File the rust off the bracket abutments until the new pad ears slide freely, then apply a thin film of silicone grease to the ears and the pins. Fit the anti rattle shims dry, not greased, and make sure the wear sensor wire is routed away from the wheel rim on cars that have one. Torque the caliper bolts to the workshop figure, pump the pedal until it is hard, and check the handbrake adjustment on the rear discs before the car is driven.

Supplied as one axle set of four pads with shims. Twelve month warranty.