Warning! Dust resulting from wear on the linings and accumulating on brake components may contain asbestos that is hazardous to health. Do not blow this dust out with compressed air or inhale it! Do not use gasoline-based solvents to remove dust. Dust should be washed off with a special brake system cleaner or methyl alcohol in a drain container. After wiping brake system components with a damp cloth, keep the cloth and the contents of the drain container in a closed and labeled container. In the future, if possible, try to use asbestos-free components.
Note. In addition to checks at regular intervals, the condition of the brakes should be checked every time the wheels are removed or if there are signs of a malfunction in the system. To ensure driving safety, the brake check procedures described below are the most important of all vehicle maintenance procedures you perform.
Signs of problems in the brake system
Disc brakes can be equipped with built-in lining wear indicators to signal the need for immediate pad replacement to prevent brake disc failure.
Any of the following symptoms may indicate a potential defect in the brake system:
- When depressing the brake pedal, the car «leads away» one way;
- Brake mechanisms during braking make scraping or squealing sounds;
- Excessive brake pedal travel;
- Depressing the foot brake pedal is accompanied by pulsations that are not related to the operation of the ABS;
- There are brake fluid leaks (usually on the inside of a tire or wheel).
If any of the symptoms listed above are detected, however, the condition of the brake system components should be checked immediately.
Brake lines and hoses
Note. In the hydraulic circuit of the brake system, mainly steel tubes are used, with the only exception being flexible reinforced hoses that serve to connect the tubes to the wheel cylinders. The condition of the flexible brake hoses should be checked on a regular basis.
1. Park your vehicle on a level surface and turn off the engine. Remove wheel caps. Loosen but do not remove all four wheel bolts.
2. Jack up the car and put it on stands.
3. Remove wheels.
4. Check all hydraulic lines and hoses of the brake path for cracks, abrasions, swellings, deformations and signs of leak development. Make sure there are no signs of brake lines rubbing against the suspension and steering components. Carefully inspect all choke connections of the hydraulic brake path for signs of leak development, check the reliability of fastening of choke bolts and nuts.
5. Bending flexible brake hoses in different directions, make sure there are no signs of mechanical damage (see resist. illustration). Make sure that the installed hoses are not twisted - as a binding, you can use the longitudinal colored strip applied to the surface of the hose.
6. By turning the steering wheel, make sure that the flexible brake hoses of the front brake mechanisms do not come into contact with the steering gear elements.
7. If signs of leak development are detected, the causes of the latter must be immediately eliminated.
Checking the thickness of the brake pads
1. Assessment of the remaining thickness of the friction linings of the outer brake pads can be made visually through the opening in the rim using a flashlight. To inspect the inner block, you will additionally need a mirror. A more accurate check of the condition of the brake pads is made after they are removed - to measure the thickness of the friction linings, you will need a caliper.
Front wheel disc brakes
Note. Experience has shown that brake pad wear on the front passenger's side is often higher than on the driver's side, so inspection should always begin on the right side of the vehicle. According to statistics, for 1 thousand kilometers under adverse conditions, there is about 1 mm of pad wear. Under normal conditions, pad wear is significantly less. Really, with a residual pad thickness of 10.0 mm (taking into account the metal substrate) it can be operated for at least another 3000 km.
1. Mark with paint the position of the front wheel in relation to the hub. This will bring the balanced wheel into its working position. Loosen the wheel bolts, then jack up the front of the car and place it on jack stands. Remove the right front wheel.
2. Use a caliper to measure the total thickness of the friction lining with the metal backing of both brake pads.
3. The wear limit of the front pads, when replacement must be made immediately, is 7 mm. Description of the procedure for replacing pads is given in Chapter Brake and auxiliary systems.
4. Having followed the alignment of the marks made during the dismantling process, reinstall the wheel. Without lubricating anything, screw in the wheel bolts.
5. Lower the car on wheels and, moving in a diagonal order, tighten bolts with the demanded effort.
Rear wheel disc brakes
1. If one is installed, remove the decorative cap and visually assess the residual thickness of the outer brake pad lining through the opening in the wheel disk - if necessary, use a flashlight.
2. Use a mirror to inspect the inner pad.
3. As for the front brakes, the minimum allowable thickness of the rear pads is 7 mm (overlay + backing).
Parking brake
1. The simplest, and perhaps most obvious, way to check that the parking brake is working properly is to hold the vehicle on a steep downhill in the transmission neutral position with the driver in their seat in the vehicle. If the parking brake is unable to hold the vehicle, it must be adjusted (see chapter Brake and auxiliary systems).