Functional check
1. With the engine off, depress the clutch pedal several times to remove vacuum from the servo unit.
2. Lightly depress the pedal and hold it in this position.
3. Start the engine. The pedal should noticeably fall down, otherwise it is necessary to check the vacuum supply:
- Check the vacuum hoses for signs of material aging and other damage. Replace if necessary.
- Disconnect the vacuum hose from the servo block and with the engine running at idle, make sure that the vacuum reaches the block by plugging the end of the hose with your thumb.
- Disconnect the vacuum hoses, release the mounting clip and remove the control valve from the vehicle.
- Blow into the control valve from the side of the servo unit. Air must pass through the valve.
- Try to suck air through the valve (again on the servo side). The valve must be closed. If these conditions are not met, replace the valve.
Removing
1. Remove the clutch master cylinder.
2. Disconnect the vacuum hose from the servo unit.
3. In the passenger compartment, disconnect the servo pusher from the clutch pedal. Give fixing nuts and remove a side of the servo drive from the car.
Installation
Installation is in the reverse order.
1. Check the protrusion length setting of the servo unit push rod, make the necessary adjustment (see accompanying illustration):
- On the removed servo block, measure the distance from the support end surface of the block to the center of the hole for installing the pusher pin to the clutch pedal (In the illustration). The nominal value is B = 130 mm.
- If adjustment is required, loosen the locknut and move the pusher tip in the desired direction, then re-tighten the locknut firmly.
- Measure the distance from the bearing surface of the master cylinder to the outer edge of the front pushrod of the servo unit (And in the illustration). The nominal value is A = 1.30÷1.55 mm.
- To adjust, fix the pusher and move its tip in the appropriate direction.
Note. If the front pushrod needs adjustment greater than 0.5mm, the servo is defective and must be replaced.
2. Tighten the nuts securing the servo unit to the required torque.
3. Check the height and free travel of the clutch pedal, correct if necessary.