Pic. 8.13. Rear drum brakes
1 - hub cover; 2 - check; 3 - crown protection; 4 - nut; 5 - remote washer; 6 - external bearing; 7 - brake drum; 8 - inner bearing; 9 - sealant; 10 - spring plate; 11 - spring; 12 - brake shoe; 13 - self-regulator wedge; 14 - spring; 15 - spring; 16 - air remover; 17 - air extractor cap; 18 - pad fastening disc; 19 - bolts securing the cylinder; 20 - rubber plug of the control hole; 21 - spring peg 11; 22 - axis of the rear hub; 23 - self-regulator spring hole; 24 - lower spring; 25 - self-regulator spring; 26 - brake cylinder; 27 - a nest of brake pads; 28 - fixing bolt; 29 - spring peg.
1. Starting disassembly of the drum brake, it is necessary to substitute wedges under the front wheels, loosen the rear wheel bolts, raise the rear of the car, put it on stands and remove the rear wheels.
2. Then lift up with a screwdriver and remove the hub cap 1 (pic. 8.13).
3. Straighten and remove the safety pin and safety ring (photo 8.23 and photo 8.24).
4. Unscrew the hub nut 4, remove the safety washer 5 and the outer bearing 6 (pic. 8.13 and photo 8.25).
5. Check if the hand brake is fully released, and then remove the brake drum. If there are difficulties when removing the drum, you must first move the brake cheeks away from it by inserting a screwdriver through one of the holes left after the fastening bolts, the wheel to the drum and pushing the self-regulator wedge up (photo 8.26).
6. Clean the brake drum, cheeks and cheek mounting disc (photo 8.27).
7. Remove the protection from the plates 10 and remove the springs 11, pressing the cheeks against the disk 18. To do this, grab the plates with tongs, press them towards the disk and turn 90°. Sometimes a support is needed for the wheel 21 so that it does not move back while pressing the plate.
Remove the plates 10, springs 11 and wheels 21 from the hole in the disc that secures the cheeks (pic. 8.13).
8. Mark the location of the cheek springs and the expansion bar. Then, lifting with a screwdriver, move and remove the lower ends of the cheeks from the socket 27 at the support fingers. Drink and take out the lower tightening spring 24.
9. To take out the top terminations of cheeks from nests in brake cylinders. Unhook the spring 25 of the self-regulator wedge 13 and the upper tightening spring 14, remove the cheeks (photo 8.29).
10. Disconnect the handbrake cable from the right hand brake lever (photo 8.30).
11. Fix the expansion bar in a vice and disconnect the cheeks, then remove the self-regulator wedge and spring (photo 8.31).
12. If smudges of brake fluid from the cylinder are visible, it is necessary to replace the gaskets or the entire cylinder. If only the gaskets are replaced, the cylinder must not be removed from the vehicle. You only need to:
A) Clamp the flexible pipe in front of the cylinder and unscrew the bleeder using an Allen wrench with a suitably deep socket.
b) Place a flat container under the cylinder, lift the rubber covers and remove both pistons with springs and gaskets.
V) Rinse the piston and cylinder in alcohol, wipe dry. Check work surfaces. If there are small scratches, you can try sanding them with 500 or 600 grit sandpaper. Rinse and put the rubber casings on the piston, turning them outward.
G) Holding the piston with your fingers on the rubber casings, install new gaskets in the grooves on the pistons. Coat the ground surface of the piston with a thin layer of silicone grease. Insert the spring and pistons into the cylinder. Install the rubber casing into the grooves of the cylinder. Piston gaskets pre-lubricated with brake fluid are inserted into the middle of the cylinder with a large outer diameter.
13. If the working surfaces of the piston or cylinder are subject to severe corrosion, or if the pistons are stuck in the cylinder, it is necessary to replace the cylinder with a new one. This is done as follows:
A) Follow steps 12-12a.
b) Unscrew the brake line connection from the cylinder.
V) Unscrew the two bolts 19 securing the cylinder to the disc 18 and remove the cylinder (pic. 8.13).
Attention: If it becomes necessary to replace the disc that secures the brake pads or the wheel hub axle, it is necessary to unscrew the four bolts from the suspension beam (photo 8.32).
G) Screw the new cylinder to the disc, loosen the air bleeder and pressurize the brake pipe.
14. Install the brake pads in the reverse order of removal. It is necessary to pay attention that the protrusion of the self-regulator wedge is on the side of the disc that secures the pads.
15. Remove the clip from the flexible brake pipe. Wait until the liquid begins to flow out of the air bleeder hole, and screw in the air bleeder.
16. Fasten the handbrake cable (photo 8.30).
17. Check the condition of the brake drum. If the drum is scratched or has a clear threshold at the border of contact with the pads, it must be turned. If, after turning, the diameter of the drum exceeds 181 mm, it must be replaced with a new one.
Attention: Elements such as brake pads and a drum cannot be replaced on one wheel, only on both at once. If only one wheel is replaced, the vehicle may skid to the side when braking.
18. If traces of bearing grease are visible on the inside of the drum, this indicates damage to the seal 9. To replace the seal, it is necessary to lift it with a screwdriver and remove it (photo 8.33).
19. If a strong noise of bearings was heard before disassembling the drum, it is necessary to replace them with new ones. To do this, do the following:
A) Knock out the inner tapered bearing 8 together with the seal 9 (pic. 8.13).
b) Knock out the outer races of the bearings from the drum. Both for disassembly and for the subsequent assembly of the track, it is necessary to use appropriate metal tubes and punches turned to size. Rinse the hub.
Installation
V) Check if the bearing seats in the drum are clean. Then drive both tracks with a smaller diameter of the inner holes inward until they stop (pic. 8 12).
Pic. 8.12. Hub laying
1 - outer bearing track; 2 - track of the inner bearing; 3 - external conical bearing; 4 - inner conical bearing.
G) Coat the inner bearing with grease and install it in the track. Lubricate the lip of the hub seal and drive it in line with the edge of the hub.
d) Squeeze out into the hub such an amount of lubricant that it fills the entire space between the track rings to the height of their inner faces.
20. After replacing the seal or bearings, the drum must be pushed onto the pin of the hub axle.
21. Lubricate the outer bearing and put it on the hub axle trunnion, advancing to the track. Then put on the safety washer so that its tooth enters the groove, and tighten the nut with a torque of 20 Nm. Rotate a few times to loosen the bearings. Loosen the nut half a turn and then tighten again slowly. To more accurately check the bearing clearance, you can put on the wheel. After obtaining a normal clearance between the bearings and achieving ease of rotation of the drum, stop tightening the nut.
22. Then you need to put the crown protection on the nut and install a new pin.
23. Half fill the hub cover with grease and lightly hammer it into the hub hole
24. Lower the rear of the car and depress the brake pedal several times to loosen the pads.
25. If the brake pads have been replaced, the handbrake must be adjusted.
26. If the brake cylinder or gaskets are replaced, air must be bled from the system.
Visitor comments