REMOVAL & INSTALLATION Fixed Caliper
See Figures 1 through 7
These procedures apply to front or rear brake pads on all models, but the 190D, 190E, 300SD, 380SE, 380SEC, 380SEL, 500SEC and 500SEL which utilize floating calipers on the front wheels.
- Remove the cover plate. The cover plate is only installed on front brakes of cars with solid brake discs (not ventilated) and 57mm calipers.
- On models with the brake pad lining wear indicator, pull the cable sensors from the plug connections at the inside edge of the caliper.
- Remove the sensors from the brake lining or backing plate.
If the contact pin insulation is worn, the clip sensor should be replaced.
- On models with Teves (ATE) brake calipers, use a punch to knock the retaining pins out of the caliper. Remove the cross-spring.
- On models with the Bendix (BX) caliper, remove the locking eyes, retaining pins and pad retaining springs.
- On models with Girling calipers (usually only at rear axle), remove the locking eyes, the retaining pins and the pad retaining plates.
- Pull the brake shoes out of the caliper. Mercedes-Benz recommends a special tool, an impact puller for this, but you can carefully grab the pad backing plate ears with pliers or a piece of bent welding rod and wiggle them out. It's best to leave one pad in the caliper always.
- Use a small brush to clean the pad guides on the inside of the brake caliper. Check the dust boots for cracks or damage. If necessary, remove and overhaul the caliper.
- When the pads are removed, the pistons will move forward slightly, due to hydraulic pressure in the system. To install the pads, the pistons must be pushed back slightly. Mercedes-Benz recommends a special tool to do this, but a flat piece of hardwood will do if used carefully. Other tools will increase the chances of damaging the piston or dust boots.
It should be relatively easy to push the pistons back.
- Check the thickness of the brake disc. Refer to the brake specifications for tolerances.
- Check the brake discs for scoring or cracks. Score marks up to 0.02 in. deep can be accepted as normal scoring.
- Clean the air passages of ventilated discs with a thin piece of wire. Blow out all loose dirt. Do not clean with solvent unless the disc is removed from the car.
- Clean the rain groove in the backing plate and measure the thickness of the lining. See the Brake Specifications for minimum lining thickness.
- Apply a heat resistant, long-term lubricant to the backing plate as shown. Install the brake pad.
- Depending on the type of caliper, install the cross-spring, retaining plate, retaining pins and locking eyes.
- On cars with a brake pad wear indicator, connect the sensors into the brake lining and the cable to the plug connection.
- If equipped, install the cover plate.
- On vehicles with a pressure differential warning system (1976 and 1977), the warning indicator may light when pads are replaced. To extinguish the light, push the reset pin on the switch after replacing the lining. The switch is located on the outboard side of the master cylinder.
This procedure applies only to the front brake pads on the 190D, 190E, 300SD, 380SE, 380SEC, 380SEL, 500SEC and 500SEL.
- Use a small prybar to lift the two holding lugs on the sides of the plug connection (on the caliper) and then open the cover.
- Disconnect the clip sensor cable from the plug. Do not pull on the cable.
- Hold the sliding caliper pin and unscrew the upper hex screw.
- Swing the cylinder housing (top of the caliper assembly) out and down. Remove the brake pads.
- Disconnect the clip sensor from the brake pad backing plate.
- To install, follow Steps 8-14 of the "Fixed Caliper Removal and Installation" procedure.
When inserting the brake pads, the spring clamp must be parallel to the upper edge of the brake pad.
- Connect the clip sensor to the inner pad.
- Swing the cylinder housing up into position and tighten the sliding bolt to 25 ft. lbs. (35 Nm) using a new self-locking nut.