14:10. Removal, capital repairs and installation to the place of the main brake cylinder

Before getting to work, read the preventions provided in the beginning of the Section Pumping of the Brake System, concerning safety of work with hydraulic liquid.

Return to the end of the Section Replacement of Hydraulic Tubes and Hoses, having read information concerning the correct address with brake lines and hoses.

Removal - the models equipped with the ABS system

On the models equipped with the ABS system, the main brake cylinder is a part of the hydraulic block (address Sections Components of system of anti-blocking of brakes (ABS) - the general information and Removal and installation to the place of ABS system components).

Removal - the models which are not equipped with the ABS system

It is not necessary to try to suck away liquid a mouth by means of a tube at all - brake fluid is extremely poisonous, and such way can lead to accident.

Assembly of the secondary piston

1 — the Holder of a cuff
2 — the Cuff
3 — the Piston
4 - Cuff


1. Disconnect both wires of the battery and remove the battery (address the Head Sistemy of start and a charge).
2. On models till 1990 of the issue release the fuel filter from a fixing strip and shift it aside (address the Head Toplivnaya and exhaust systems).
3. Uncover the tank of brake fluid and merge liquid from cameras of two brake contours (there is no need to merge from the coupling contour camera on models with the manual transmission). It can be made in several ways - one of ways is liquid exhaustion directly from the tank by means of the old syringe. Other method is pumping out of liquid via the pumping gate on one of brake supports. Connect one end of a piece of a tube to the gate, and insert other end into the container capable to contain at least 1 liter of liquid. Open the gate by means of a wrench and regular firm pressings of a brake pedal make pumping out of liquid from cameras of the tank in a container. Tighten the gate.
4. Carefully clear surfaces around nipple connections of brake tubes and ports of accession of hoses. Two hoses in braids go from a tank bottom to the main cylinder. Disconnect them, having removed connecting tips from ports on the main cylinder - be careful at the same time, trying not to damage plastic connectors. Remember what hose to what port it was connected. For collecting the liquid following at the same time prepare rags, having enclosed it under connection. Stop up the disconnected hoses and ports in order to avoid hit in system of dirt and for prevention of excessive losses of liquid.
5. After weakening of nipple connections disconnect all four brake tubes from the main cylinder. Remember what tube it was connected to what port.
6. Remove two fixing nuts, then lift the main cylinder, having removed it from the block of the vacuum amplifier and take the cylinder from a motive compartment.

Capital repairs

When using compressed air put on goggles.


1. For carrying out capital repairs prepare a pure flat working surface. For collecting following from the removed components of brake fluid and for convenience in work cover a working surface with the sheet of paper or a cardboard.
2. Slightly clamp the main cylinder in a vice with soft sponges. In case there is only vice with metal sponges, use as laying for protection of the cylinder wooden whetstones. Remove rubber consolidations from connecting ports, hoses and tubes and throw out them; at assembly new consolidations have to be established.
3. Push lengthways on the cylinder primary piston, rather far that there was possible a removal from a lock finger of the secondary piston. In order to avoid damage of a mirror of the cylinder for pushing through of primary piston use a blunt object, such as wooden whetstone.
4. Allow the piston to otpruzhinit back against the stop, then take from the cylinder all assembly of primary and secondary piston together with a free plastic cover. After extraction of components record for yourself an order of their assembly and in this order spread out them on a pure working surface. If the piston does not give in to extraction, carefully connect the line of compressed air to port of a brake tube - cover the open end of the cylinder with a piece of rags in case the plunger will jump out quicker, than it was expected.
5. When cleaning components of the brake system use only patent cleaners, methyl alcohol or pure hydraulic liquid. Do not apply solvent on a mineral basis at all, such as gasolines or kerosene as they are aggressive on the relation in rubber components of the brake system.
6. Carefully clear all components, then dry their pure неворсящейся rags or compressed air. Pay special attention to the internal surface of the cylinder and ports of brake tubes and hoses.
7. Examine the internal surface of the cylinder. The surface has to be smooth and brilliant; at detection of signs of corrosion or scratches the main cylinder has to be replaced. Similarly, in case of existence of scratches or corrosion of pistons, they are also subject to replacement in a set.
8. If the cylinder and assemblies of pistons are subject to reuse, prepare service set for the main cylinder which can be acquired in representative office of SAAB. Set includes duplicates of all components which are subject to the most probable wear during the normal work of system.
9. Before starting assembly, moisten components of pistons and new cuffs from service set with pure brake fluid. Similarly grease with brake fluid a cylinder mirror.

10. Collect assembly of the piston, having established new cuffs. For the correct assembly order use the notes made previously. Enter the piston into the cylinder at first at an angle, having inserted sponges of the first cuff into the cylinder rotary motions so that the cuff was not turned out outside. After the first cuff will be entirely inserted into the cylinder, push the piston rest already perpendicularly in the cylinder. For pushing through, in order to avoid damage of a mirror of the cylinder, use a blunt tool, such as wooden whetstone.

11. Push the piston, overcoming resistance of a returnable spring of the secondary camera, and implant a lock finger. Allow a spring to push away the piston back and make sure that the lock finger holds it on the place.

Installation into place


1. Absolutely wipe the interfaced surface of the block of the vacuum amplifier and put on assembly of the main cylinder adjusting hairpins, watching that the pusher was correctly combined with the piston of the main cylinder. Establish to the place of a nut and strong tighten them.
2. Remove plugs from rigid brake tubes and according to the notes made previously connect tubes to the ports on the main cylinder. Moderately hardly delay nipple connections.
3. Insert hose connectors of the tank into the relevant ports on the main cylinder; for their correct installation use previously made notes. You watch that consolidations of ports were not forced out at installation of hose connections.
4. Add in the tank hydraulic brake fluid of the required grade to a mark a maximum.
5. For уд Pumping of the brake system).
6. On models till 1990 install to the issue into place the fuel filter.
7. Install into place the battery and connect to it wires.