Mercedes Coupes/Sedans/Wagons 1974-1984 Repair Guide

Caliper Piston Seal



Brake pads may contain asbestos, which has been determined to be a cancer causing agent. Wear an approved filter mask or respirator whenever working around brakes, to avoid inhaling dust from any brake surface. Never clean brake components with compressed air! instead, use a commercially available brake cleaning fluid.

See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Piston dust seal assembly on fixed caliper systems

Do not unbolt the two caliper halves for any reason. Remove the brake caliper for easier service.

  1. Remove the friction pads, brake line, and dust cap, then pry the clamp ring from the housing.
  3. Using a rubber-backed piece of flat steel, hold one piston in place while blowing the other one out with compressed air (7-8 psi).
  5. Remove the piston seals from the cylinder bores and examine the bores. Scored bores necessitate replacement of the entire caliper, since the inner surface is chrome plated and cannot be honed.
  7. Clean the bores with crocus cloth only, never use emery paper.
  9. Install the new seals, coating them with brake fluid beforehand, then install the (front) piston so that the projection points downward. The rear caliper pistons must be installed with the projection facing downward.

If the projection is in any other position, the brakes may squeal badly.

Floating calipers have only one piston.

  1. Install the dust cap, clamp ring and heat shield.
  3. The recess in the heat shield must fit the piston projection, but be above the shield level by about 0.004 in.

The heat shields differ for inner and outer pistons.

  1. Install the friction pads and the caliper assembly, then bleed the brakes.