Maintenance work
Checking the wear of the rear disc brake pads is carried out in the same way as on the front brakes. Here, too, the minimum dimension is 6 mm - the measurement is made together with the lining carrier plate.
At the same time as checking the linings, the condition of the brake discs is checked. The measure of wear and the sequence of work steps are described later in the text of this chapter.
Replacing rear disc brake pads
Both linings and spacer clips on the right and left must always be replaced at the same time. Only use pads with ABE.
Knock out the mounting pins of the brake pads from the outside to the inside with a suitable punch.
Remove the released spacer clip.
Install a gas wrench between the brake lining carrier plate and the brake caliper and wring out the lining.
Insert a screwdriver between the pad and the brake disc and push the pad all the way to the outer edge of the brake caliper shaft.
Check the brake fluid level in the expansion tank. It rises when the pistons are pressed. If necessary, aspirate the brake fluid with an injection syringe.
Press the other pad in the same way.
To measure the thickness of the brake lining of the rear disc, dismantle the mounting pin, remove the released spacer spring. For thicknesses less than 6 mm, including the carrier plate, the linings must be replaced.
The photo shows the fixing bolts (2), which attaches the rear brake caliper to the trailing arm (1).
At the same time, leave the opposite pad installed for the time being. Otherwise, when one piston is pressed out of its guide, another may move forward.
Remove both pads.
A rag soaked in alcohol (never petrol), clean the dust from erasing the pads in their sockets.
Use a flathead screwdriver to scrape off the caked crust from the pads and rust. Be careful not to damage the piston cups.
To avoid squealing brakes, lubricate the linings in the areas where the brake pistons fit with brake paste «Plastilube» (in the spare parts store).
Install new pads with metal gaskets.
Apply spacer spring and insert fixing pins from inside to outside.
Depress the brake pedal several times until the pads are pressed against the brake discs.
If the brake fluid has been sucked out, check its level.
Removing the rear brake caliper
Raise the car, dismantle the rear wheel.
Remove the brake pipe if the brake caliper is to be removed. To do this, open the bleed valve, depress the brake pedal once and lock in this position.
Remove the brake caliper mounting bolts.
Push the brake caliper back and forth to slightly move the brake pistons.
Remove the brake caliper.
When mounting, tighten the fixing bolts to 80 Nm. Screw the brake pipe to 16 Nm.
Bleed the brake system if the brake pipe has been unscrewed.
Before the first few meters of travel, depress the brake pedal several times to bring the pedal to normal clearance.
Replacing the cuff of the rear brake piston
Remove the brake pads.
Remove the brake caliper, the brake pipe remains connected.
The brake piston should protrude a little further above the brake caliper housing when replacing the cuff. If not, have an assistant depress the brake pedal a little so that the piston protrudes about 10mm. Do not change the mounting position of the brake piston. The piston must, with the protruding side of the pressure surface, fully press on the brake lining fixing plate. If necessary, turn the piston slightly.
Press out the spring ring on the brake piston collar with a narrow screwdriver.
Remove the old cuff.
Left: knock out the fixing pins of the rear brake pads from the outside to the inside.
On right:Press the inner and outer brake pistons back with a gas wrench. So the linings are then easier to pull out of the shafts.
Check the position of the piston: the piston must press the protruding side of the pressure surface completely onto the brake lining fixing plate; if necessary, turn the piston slightly.
Insert a new cuff into the groove of the brake piston, pull on the roller on the brake caliper and secure with a spring ring.
Check: The seal must be evenly located in the brake caliper around the entire perimeter. It must fit flawlessly in the groove of the brake piston.
Removing the rear brake disc
Remove the rear brake caliper. The brake pipe remains connected. Tie the brake caliper with wire to the body.
Unscrew the fixing bolt in front of the brake disc.
Now remove the brake disc. If it does not work, slightly turn back the adjusting wheel of the handbrake pads (see «Handbrake adjustment»).
Clean the mating surface of the brake disc on the wheel hub and install a new brake disc. Tighten the fixing bolt to 4 Nm.
Adjust handbrake pads.
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