FIG 10:1 Diagrammatic layout of the braking system for drum brakes. The principle is the same for disc brakes
10:3 Removing drum brake shoes
10:6 Servicing drum brake master cylinder
10:7 Servicing disc brake master cylinder
10:9 Removing and servicing disc brake calipers
10:10 Removing and servicing front disc and hub
10:11 Removing and servicing rear brakes
10:14 Servicing handbrake cables
10:15 Brake hoses and pipelines
The layout of the 356A braking system is shown in FIG 10:1 and this system is representative of that fitted to later cars by the substitution of disc brakes for the drum brakes illustrated. These disc brakes were fitted to the 356C models from July 1963, starting with car No. 126.001 for the coupé (also from car No. 215.001), and from car No. 159.001 for cabriolet models.
Returning to the illustration, the principle of operation is that master cylinder 1 has a pushrod which is directly connected to brake pedal 4. A study of FIG 10:10 will enable the construction of the master cylinder to be followed. Reservoir 2 keeps the hydraulic system full of fluid, keeping it topped-up if fluid is lost through leakage. Pressure from the pedal and pushrod pushes the master cylinder piston down the bore, forcing fluid through the pipe system 5 to wheel cylinders 7 and 8 in the brakes. This pressure forces the pistons in the wheel cylinders outwards to expand the brake shoes inside the drums or, in the case of disc brakes, the pads into contact with the discs.
The mechanical handbrake 11 operates on the rear brakes only, through the agency of cables. With disc brakes, there are separate shoes which are expanded inside a drum which is part of the disc, as shown in FIG 10:19.
Every 3000 miles, check the level of brake fluid in the reservoir and top-up with the recommended fluid if more than ⅝ to ¾ inch below the upper edge of the reservoir. Never use mineral oil. The reservoir will be found under the inspection plate for the steering gear. Remove the spare wheel first. On 356C cars the reservoir is separate from the master cylinder and is located near the spare wheel as shown in FIG 10:2. Before removing the cap, clean all round it so that dirt cannot fall into the reservoir and check that the vent hole in the cap is clear. If unusually frequent topping up is required, check the braking system at once. Apply heavy pedal pressure and have a second operator look for leaking pipes and joints and leaking master cylinder. Remove brake drums and look for evidence from wheel cylinders.
At the same mileage, check the adjustment of the brakes and handbrake cables (after 1962 the handbrake adjustment can be left until every 6000 miles).
FIG 10:1 Diagrammatic layout of the braking system for drum brakes. The principle is the same for disc brakes
Key to Fig 10:1
1 Master cylinder
2 Fluid reservoir
3 Stoplight switch
4 Brake pedal
5 Brake pipelines
6 Pipe distributor
7 Single-acting wheel cylinder (front)
8 Double-acting wheel cylinder (rear)
9 Front brake
10 Rear brake
11 Handbrake control
12 Handbrake cable
Check disc brake pads every 6000 miles. Also check the rubber boots on the caliper cylinders. On cars fitted with disc brakes, carry out a complete check of the braking system every 12,000 miles.
On cars fitted with drum brakes, carry out a complete check of the system every 18,000 miles.
Be particularly careful when topping up, not to drop fluid on paintwork, as it is a solvent.
Adjusting brakes:
Excessive free play of the brake pedal calls for brake adjustment, providing the play is not due to fluid troubles. First make sure the front wheel bearings are correctly adjusted, then jack up the car, take off the hub caps and release the handbrake. Depress brake pedal several times to centralize shoes in drums. Note that disc brakes are self-adjusting so that these instructions apply to drum brakes only.
The brake adjusting nuts are accessible through a hole in each brake drum and they may be turned by a screwdriver, as shown in FIG 10:3. It is important to turn in the right direction, and for tightening (or expanding) the brake shoes the following table will be found useful:
| Adjusting | Direction of screwdriver | |
| Brake | nut | handle |
| Right, front | Upper | Upward |
| Lower | Downward | |
| Right, rear | Front | Downward |
| Rear | Upward | |
| Left, front | Upper | Downward |
| Lower | Upward | |
| Left, rear | Front Upward | |
| Rear | Downward |
It will also be helpful to remember that all the nuts have righthand threads.
Using the screwdriver as a lever, turn the adjusting nut until the brake shoe is tightly locked against the drum.
Back off about 7 or 8 notches and check that the drum turns freely. Repeat on the second nut and then adjust the other brakes. Check brake pedal travel and carry out a road test.
Adjusting handbrake, 356A and B:
Wear of the rear brake linings may call for adjustment of the handbrake at the adjusting nut shown in FIG 10:4. This is located on the centre line just behind the front axle. First, check and adjust the footbrake if necessary. Then jack up the car, apply the handbrake and check that the braking effect is even on both rear wheels. If it is not, refer to FIG 10:22 and adjust the two outer cable nuts until braking effect is balanced. Normally, this should not be required, and adjustment can be made at the nut indicated by the arrow.
Pull up the handbrake lever by about 2.75 to 3.15 inch (7 to 8 cm). Loosen locknut and tighten adjusting nut until rear wheels begin to drag. Tighten locknut.
Adjusting handbrake, 356C:
Raise car on stands and remove rear wheels. Release handbrake and push brake pads back until disc turns freely. Insert screwdriver through hole in hub as shown in FIG 10:5 and turn adjusting nut until disc just begins to drag. Repeat on opposite brake.
Remove rubber cover from tunnel in front of gearlever. Check that brake equalizing beam is at right angles to the cables as shown in FIG 10:6. Cable nuts should touch beam without play. Carry out any correction found to be necessary. Adjust front cable at nut shown in FIG 10:4 until there is no play at the handbrake handle. Back off each adjusting nut at the rear brakes by 4 to 5 teeth.
Before driving, it is important to depress the brake pedal several times to its fullest extent. This will settle the pistons and brake pads into their working positions. Check level of fluid in master cylinder reservoir.
Front:
Remove front wheels and brake drums (see Chapter 8). Refer to FIG 10:7 and remove the pressure springs 2 and 10 by pressing and turning the retaining collars. Pull one shoe outwards and release the tension on the return springs 3 and 8. Remove the second shoe. If brake will be dismantled for some time, wire the plungers of each brake cylinder 4 and 7 or use a strong rubber band to prevent accidental ejection. It is a good idea to put a notice on the brake pedal to stop anyone depressing it and forcing the pistons out of the cylinders.
If the linings are worn, refer to Section 10:5.
Blow drum and backplate free from dust and check for fluid leakage and broken springs. Check hub bearings and seal. Check braking surface of drum and have it refaced or renew the drum if cracked or beyond repair.
Key to Fig 10:7
1 Brake backplate
2 Pressure spring with collar
3 Return spring
4 Lower brake cylinder
5 Lower adjusting nut
6 Upper adjusting nut
7 Upper brake cylinder
8 Return spring
9 Brake shoe with lining
10 Pressure spring with collar
Key to Fig 10:8
1 Pivot bolt for handbrake lever
2 Brake backplate
3 Secondary brake shoe
4 Pressure spring with collar
5 Handbrake cable
6 Return spring
7 Adjusting nut
8 Brake cylinder
9 Return spring
10 Pressure rod
11 Primary brake shoe
12 Pressure spring with collar
13 Return spring
14 Adjusting nut
Reassemble brake in the reverse order, fitting the shoes so that the notches in the webs are adjacent to the piston ends of the cylinders (see FIG 10:7). This also shows the correct position for the return springs. Fit one shoe and then pull on the other until it can be located correctly. If necessary, clean out the hub and repack bearings with 50cc (1½ oz) of multi-purpose lithium-based grease. Adjust bearings (see Chapter 8). When assembling is completed, adjust brake and check system. It is important to fit new linings on both front wheels at the same overhaul.
Rear:
Loosen axle nut while car is on the ground. Jack up and then remove rear wheels. Remove axle nuts and remove brake drums with a puller. Refer to FIG 10:8 and press and turn retainers to release springs 4 and 12. Remove shoes with return springs and handbrake mechanism. Detach handbrake cable. Release handbrake lever by removing pivot bolt. Refer to preceding instruction for front brakes to prevent accidental ejection of the brake cylinder pistons.
There are instructions in Section 10:5 if the linings are worn. Blow dust from the drum and backplate and check drum for cracks or excessive wear. Worn drums may sometimes be restored by refacing. If the linings are to be renewed, remember that it is essential to renew them on both rear wheels at the same time.
Having checked for leaks at the cylinder, or from the hub, check all springs and then reassemble in the reverse order. Fit the shoes with the handbrake lever and pressure rod correctly located as shown in the illustration. This also shows the correct positions for the return springs. Leave tightening the axle nut until the car is on the ground. Tighten to a torque of 400 lb ft and secure with a new splitpin. Adjust brakes and handbrake and test on the road.
Removal of the brake shoes is covered in the preceding Section.
Removing front backplates:
Having removed brake shoes as instructed in the preceding Section, detach brake hose as specified in Section 10:15. Prop the brake pedal in a slightly depressed position to prevent undue loss of fluid. An alternative method to detaching the hose before removing the backplate is to loosen the hose slightly, cut the locking wire and remove the backplate securing bolts and with the backplate pulled off, turn the plate to unscrew it from the hose. At no time turn the hose with the inner end secured.
Clean the plate and check for distortion. Clean contact surfaces before refitting. Do not forget to rewire securing bolts.
Removing rear backplates:
Having removed the brake shoes as instructed in Section 10:3, unscrew the bracket for the handbrake cable. Unscrew the brake pipeline from the wheel cylinder. The backplate is secured under the axle bearing cover. Remove the cover and be ready to catch any transmission oil which may drain out. Refit the cover temporarily to prevent further loss of oil.
Clean plate and check for distortion. Clean contact faces and renew seals. Refer to Chapter 7 for details of correct assembly and shimming procedure if a new plate is fitted Making sure that rubber seals are correctly seated, tighten cover bolts 8G to a torque of 29 to 32½ lb ft or bolts 10G to 40 to 43½ lb ft. Reassemble brake as in Section 10:3. Tighten axle nut to a torque of 400 lb ft and lock with a new splitpin. Adjust footbrake and handbrake and bleed the system as instructed in Section 10:13.
Key to Fig 10:9
1 Boot
2 Plunger
3 Piston
4 Rubber cup
5 Bleed valve dust cap
6 Bleed valve
7 Spring seat
8 Spring
9 Cylinder housing
10 Adjuster
11 Adjusting screw
Front wheel brake cylinder:
The components of the cylinder are shown in FIG 10:9. Note that there are two single-ended cylinders in each front brake, whereas each rear brake has a single double-ended cylinder.
Removing cylinder:
Remove the brake shoes as instructed in Section 10:3. If one of the cylinders is not going to be disturbed, wire the plungers or use a stout rubber band to prevent inadvertent ejection. If upper cylinder is to be removed, detach pipeline from cylinder connection behind back-plate (see top arrow in FIG 10:23). Release cylinder from backplate. If lower cylinder is to come off, remove flexible hose (see Section 10:15).
Servicing cylinder:
Do not use petrol, mineral oil or similar solvents on the dismantled parts of the hydraulic system. Use only methylated spirit or correct brake fluid for cleaning purposes. Dismantle the cylinder by removing rubber boot 1 (see FIG 10:9). Withdraw internal parts 2, 3, 4, 7 and 8. If tapping on a wooden bench will not move them, try gentle air pressure in the pipe connection hole, but be careful to drape a piece of cloth over the assembly to catch the bits. Clean all the parts and check piston 3 and bore of cylinder 9 for wear, scoring or pitting. Reject unsatisfactory parts and always renew cup seal 4. It is not safe to take chances with brake assemblies. Clean, dry, pistons must move freely in cylinder bores. Maximum clearance must be not more than .26 mm (.01 inch).
To reassemble, coat the piston, cup seal and cylinder bore with a very thin film of genuine brake cylinder paste. Do not let mineral oil or grease contact any of the parts. When fitting the seal into the bore, take care not to trap or turn back the lip. The flat face should be outwards, to contact the flat face of the piston. If the cylinder is renewed, make sure that it has the correct bore of ¾ inch.
Reassembling:
Reverse the order of dismantling, taking care to fit each cylinder so that the operating piston faces in the direction of wheel rotation (see FIG 10:7). Complete the assembling by following the instructions, in Section 10:3. Bleed the brakes and fit a dust cap to the bleed valve (see Section 10:13).
Rear wheel brake cylinder:
This is similar to the one shown in FIG 10:9 except for the fact that the adjuster 10 and 11 is not used, the cylinder bore being clear through the housing and two pistons and seal assemblies being used back-to-back. The cylinder is thus double-acting. Remove in the same way as instructed for the front wheel cylinders, putting the bleed screw cap on the disconnected pipeline to prevent dirt from entering. Replacement cylinders must have a bore of ¾ inch.
Dismantle and service rear wheel cylinders in the same way as front wheel cylinders. Reassemble and then refit according to the instructions in the preceding section. Reassemble the brake as instructed in Section 10:3. Bleed the brakes and fit dust cap to bleed valve (see Section 10:13).
If brake drums which are worn, scored or oval have not reached the wear limit of 282 mm (11.11 inch) on internal diameter, they may be machined. This must be carried out on accurate machinery, so that the surface is smooth and concentric with the hub mounting. Do not polish after machining. Maximum permissible taper of braking surface is .10 mm (.004 inch), and maximum runout .10 mm (.004 inch). To secure even braking the pairs of drums, either front or rear, should not differ from each other by more than .20 mm (.008 inch) on internal diameter. Drums which are up to the wear limit or those with bearing seats which do not permit a press fit of the front wheel bearings, must be renewed. The same applies if the rivets in the rear drums are insecure. Damaged wheel bolts may be renewed and oversize bolts are available if standard ones fit too loosely.
FIG 10:10 Components of drum brake master cylinder. Parts are similar for disc brake cylinder but reservoir is separate
Key to Fig 10:10
1 Cover
2 Gasket
3 Threaded nipple and strainer
4 Fluid reservoir
5 Gasket
6 Master cylinder housing
7 Stoplight switch
8 Valve seat
9 Check valve
10 Pressure spring
11 Main piston cup
12 Washer
13 Piston
14 Secondary piston cup
15 Piston stop plate
16 Locking ring
17 Boot
18 Brake pushrod
Brake shoes cannot be relined, and service replacements must be fitted. It is essential to fit brake shoes of identical design, and with linings to factory specification. Although there may be discrepancies between the front and rear pairs of brakes, it is not permissible for one front brake to differ from the other, nor for rear brakes to differ from each other.
Replacement shoes are available with standard linings 7 mm thick (.28 inch) suitable for drums with an internal diameter of 280 to 281 mm (11.024 to 11.062 inch). Oversize linings 7.5 mm thick (.30 inch) are for drums which are 281 to 282 mm in diameter (11.062 to 11.11 inch).
Take the greatest care to prevent contact of brake linings and braking surfaces with grease or oil. Brake linings which have been contaminated with leaking oil, grease or brake fluid, cannot be cleaned.
New brake linings may be bedded-in by applying dry chalk (not wax crayon) to the surface and checking after application to the drum. Marked areas can be reduced by filing until a good even contact is shown, but do not remove more than .30 mm (.012 inch).
The components of the master cylinder are shown in FIG 10:10.
Removing:
Jack up front end of car and remove tools and spare wheel from luggage compartment. Move mat to one side and remove cover over steering gear (4 screws). Remove cable from stoplight switch 7. Detach pipelines from master cylinder and put bleed valve caps on the ends to exclude dirt.
Working inside car, remove mat and floorboard from pedal side (see FIG 10:11). Spanner is shown on master cylinder pushrod. Do not touch this adjustment when removing cylinder. Pull rubber boot off cylinder (see arrow). Release flange of cylinder from bulkhead and lift away, keeping reservoir upright.
Reconditioning master cylinder:
1 Empty fluid out of reservoir. If necessary, remove reservoir by unscrewing nipple 3. Unscrew stoplight switch 7.
2 Prise out locking ring 16 to release plate 15. Spring pressure will push piston 13 out of bore.
3 Tap out parts 12, 11 and 10 (with 9) in that order. Valve seat 8 is at the bottom of the bore and may need prising out.
Cleaning and checking:
Discard the seals. Always fit new seals, which are available in kit form. Do not use petrol, benzol or similar solvents for cleaning, and keep all rubber parts from contact with mineral oil or grease. The only cleaning fluids permissible are methylated spirit or correct brake fluid.
FIG 10:11 Adjusting length of master cylinder pushrod (see top right in FIG 10:10). Arrow points to rubber boot round pushrod
When clean, check the parts for wear, scoring or pitting. Discard piston and cylinder if surfaces are not smooth and polished. Where reservoir screws into cylinder there are two holes drilled through into the bore. Check that these are clear. When the brake pedal is fully released and the piston pushed right back in the bore, the small hole is uncovered and fluid from the reservoir can enter the system if any has been lost through leakage. This port is closed on the first small application of the brake pedal. The cleaned and dried piston must produce suction when moved to and fro in the cylinder. If the cylinder is renewed, check that the bore is ¾ inch.
Reassembling:
Before refitting the internal parts, put a thin film of genuine brake cylinder paste on the piston and seals and on the cylinder bore. The first part to be fitted is valve seat 8. From the kit of seals, fit a new valve rubber inside check valve 9 and insert the valve in the end of the spring. Drop the assembly into the bore, valve first. Push seal 11 down the bore, lip first. Take great care not to trap or turn back the lip as it enters. Follow up with washer 12. Use the fingers to fit a new seal 14 to the piston. The lip must face into the bore, and once more it is necessary to be careful not to trap or turn it back on itself. Fit washer 15, press the piston down the bore a short way and refit locking ring 16, making sure it is well seated.
When fitting the reservoir, set the mark at the bottom on the centre line of the master cylinder and pointing towards the stoplight switch. Check that the vent hole in the cap is clear.
Installing:
Do this in the reverse order to dismantling. First apply some sealing compound to the mounting flange and offer it up to the bulkhead, taking care to ensure that the pushrod enters correctly. Refit the pipes and the switch cable.
FIG 10:12 Arrows indicate essential clearance between disc brake pads and cross-spring. Retaining pin clips are shown at A
There must always be slight free play in the brake pedal before the pushrod touches the piston, as shown by the inset in FIG 10:10. To adjust for correct clearance, slacken the locknut on the pushrod and use a spanner on the pushrod flats as shown in FIG 10:11. Correct clearance is 1 mm (.04 inch).
Fill the reservoir with correct fluid and bleed the system as described in Section 10:13.
The master cylinder for disc brakes differs from that fitted to cars with drum brakes in two ways. The first is that the fluid reservoir is mounted inside the luggage compartment as shown in FIG 10:2. The second is that a special purging valve is fitted in place of valve 9 in FIG 10:10. The spring-loaded conical valve is drilled with a small hole so that the hydraulic system becomes completely depressurized when the brake pedal is fully released.
The disc brake master cylinder is not interchangeable with the one fitted to drum brakes. For identification purposes it carries a metal band reading ’Zylinder hat Spezial-Bodenventil’ which may be translated as ’This cylinder has a purging check valve’.
Apart from ensuring that the correct check valve is fitted, servicing instructions for this master cylinder will be the same as those for the drum brake master cylinder.
Standard pads are marked TE.5 and those for competition work FE.4. Change competition pads for standard ones at the start of winter. Use the same type of pads throughout, and renew them in axle sets, that is, always fit new pads to both front brakes or both rear brakes, not to one brake alone. Mark used pads for correct replacement. Do not interchange them. Thickness of braking material on new pads is 15 mm (.59 inch). Minimum thickness when worn is 2 mm (.08 inch). This is indicated by the arrows in FIG 10:12. There must always be clearance between the pad segments and the cross-spring.
To renew pads, jack up car, fit stands and remove wheels. Refer to FIG 10:12 and remove clips A. Depress cross-spring and push out retaining pins as shown in FIG 10:13. Mark pads if they will be refitted. Remove pads with a hook.
Before pads can be refitted, the pistons must be pressed back in their bores. To avoid damage, do not use metal levers to do this, but apply pressure with a piece of wood. This action will result in a rise of fluid level in the master cylinder reservoir, so take the precaution of syphoning out some of it, using a clean piece of tubing not contaminated with dirt or mineral oil.
With the pistons pressed back, clean the pad recesses free from dirt, using nothing else but methylated spirit as a solvent. Check that dust covers and clamping rings are serviceable. Clean disc with fine emerycloth. Check that clips for retaining pins are not damaged or bent.
Refit the pads, retaining pins, cross-spring and clips and check that the pads can move freely. If they bind, a touch of a file on the edges should clear them. Repeat procedure on opposite brake. Do not fit new pads on one side alone.
Top up the fluid in the master cylinder reservoir and depress the brake pedal several times to set pad clearance correctly. Check the fluid level again and then carry out a road test.
New pads have a tendency to fade a little at first, but after running in for 125 miles the brakes will become fully effective. It is a good plan not to brake heavily from high speeds during this running-in period, but to apply the brakes lightly at not too frequent intervals.
Removing, front:
1 Jack up car, fit stands and remove wheels. Remove brake pads as instructed in Section 10:8.
2 Prop brake pedal slightly depressed to avoid undue loss of fluid and then loosen flexible hose connection on back of caliper by about one turn.
3 Remove bolts securing caliper to stub axle flange, withdraw unit and detach hose, taking care not to twist or strain it.
Removing, rear:
This is done in similar fashion to the preceding instructions, but release the pipeline and then detach the caliper by lifting it up and away from the pipe.
Dismantling:
1 Remove brake pipeline connecting the caliper halves. Remove the four socket-head screws to separate the caliper housings.
2 Refer to FIG 10:14 and prise off clamping ring 1 to release dust cover 2. Apply gentle air pressure to the fluid inlet to push out the piston. Let the piston face the bench or drape the assembly in cloth so that the piston will not be damaged.
3 Using a piece of wood, prise piston seal 4 from its groove in the cylinder. Take great care not to damage the surface or the groove.
Cleaning and inspection:
Clean the parts with methylated spirit or correct brake fluid. Do not use petrol, benzol, or similar solvents and do not let the rubber parts contact mineral oil or grease. Discard the seal. Check the piston and cylinder bore for wear, scoring or pitting and renew faulty parts. It is dangerous to reassemble parts which may lead to brake failure. If the self-adjusting mechanism for the piston is found to be defective it will be necessary to renew the complete piston unit. Not only the piston seal must be renewed at each overhaul, but also the dust cover, the socket head screws, the spring washers and the nuts.
Reassembling:
Before refitting, put a thin coat of genuine brake cylinder paste on the seal, the piston and the cylinder wall. Use the fingers to fit the seal in its groove. Fit each piston as shown in the lower views of FIG 10:14. The sheet metal gauge has an included angle of 20 deg. The stepped down part of the piston face must point away from the direction of disc rotation which is indicated by the arrows.
Always insert the gauge from the side nearest the axle centre. On front brake calipers put the base of the gauge on the bottom face of the caliper recess. On rear brakes, place it against the top face.
Use methylated spirit to wipe clean the mating surfaces of the caliper halves and lightly bolt together. Tap halves into alignment so that the pad recesses are flush with each other. Tighten bolts in two stages, first to 12 lb ft (front brakes) and 7 lb ft (rear brakes). Then tighten fully to 24½ lb ft (front brakes) and 13 lb ft (rear brakes). Effective tightening is best done with the caliper mounted in a vice. Use soft jaws and hold by the fixing lugs, taking care that they are not damaged.
Fit dust covers and clamping rings. Install connecting pipe. Refit calipers in reverse order to removal. When fitting the brake pipe banjo connection to the back of the front caliper, select a suitable gasket so that the banjo cannot contact the caliper face.
FIG 10:14 Components of one half of a disc brake caliper (top). Bottom view shows correct setting of pistons, using gauge. Arrows indicate direction of disc rotation
Key to Fig 10:14
1 Dust cover clamping ring
2 Dust cover
3 Piston
4 Piston sealing ring
5 Caliper half with cylinder
FIG 10:15 Prising off grease cap from disc brake front hub. Inset shows Allen key slackening clamping nut on axle
FIG 10:17 Splitpin for slotted nut on end of handbrake cable (black arrow). Remove handbrake expander by lifting shoe (white arrow). Rear disc brake
Removing:
First remove the caliper as instructed in Section 10:9. Remove the splitpin from the squared speedometer drive shaft if removing the lefthand grease cap. Prise off grease cap as shown in FIG 10:15 and then slacken clamping screw in axle nut as shown in the inset. Uncrew nut, use both hands and withdraw disc and hub. If tight, do not use a hammer on disc but resort to a puller. The disc shield can be removed if required by turning back the locking tabs and removing the four bolts securing it to the stub axle
Removing and installing bearings:
Mark disc and hub for correct reassembly, remove bolts and withdraw hub. Press out inner taper-roller bearing and seal using tools VW.407, VW.421 and VW.447g. The outer race of the outside bearing is pressed out with tools VW.407, VW.418 and VW.447f, the front face of the hub standing on a spacer made from steel tubing (see FIG 10:16). Outside diameter of tube 100 mm (3.94 inch), inside bore 90 mm (3.54 inch) and length 30 mm (1.18 inch).
Clean bearings and hub free of grease. Check bearings for wear and if to be renewed, remember that there are various makes such as Timken, SKF or FAG. A complete bearing must have parts which are all of the same make.
To refit the bearings, heat the hub to 120° to 150°C (248° to 270°F). Press in the inner bearing with tools VW.407, VW.447i, VW.401 and the spacer. Insert the inner race and press in the oil seal with its open side facing the bearing until it is flush with the hub. Use tools VW.410, VW.433, VW.401 and spacer. Press in the outer race of the outer bearing using tools VW.407, VW.447h and VW.401.
Fill hub with about 50cc or 1½ oz of multi-purpose lithium-based grease. Line up marks and fit disc, tightening bolts to 16 to 17½ lb ft. Make sure that there is a spacer under each bolt head and a new spring washer under each nut. Tighten caliper bolts to 56½ lb ft torque.
Disc runout:
Having refitted the hub and adjusted the bearings according to the information in Chapter 8, mount a dial gauge so that its tracer contacts the braking surface of the disc near the outer edge. The maximum runout which is permissible is .20 mm (.008 inch). If seriously out, check contact faces of hub and disc for dirt or burrs.
The final operation after refitting all parts is to bleed the brakes (see Section 10:13).
Removal of the calipers has been covered in Section 10:9. To remove the disc and the handbrake parts proceed as follows:
1 Adjacent to the wheel studs are two countersunk screws. Remove these and pull off the disc. Remove splitpin arrowed in FIG 10:17, unscrew nut from cable end and pull cable out from the back (part 4 in FIG 10:18).
2 Using a screwdriver as a lever under the brake shoes at the rear (see white arrow in FIG 10:17), lift the shoes and remove the brake expander and spring. The action of the expander can be seen in FIG 10:18. As the struts are drawn together by the cable they expand the shoes inside the drum.
3 Resting a screwdriver on the disc flange, lever up the shoes at the front end to enable the adjusting assembly to be withdrawn and the front spring to be detached from the shoes.
4 Spread shoes apart until retaining springs are free, then remove both shoes to the rear. Remove shoe retaining springs.
5 Remove shroud plate from back flange. Remove axle nut, using tool P.36. Mark hub and shaft for correct location on reassembly. Tap hub off with a soft-faced hammer. Oil will drain out, and this can be prevented by preliminary draining of the transmission.
6 Remove anchor plate 19 (see FIG 10:19), followed by the backplate. Note the oil seal O-rings. Service the axle bearing and oil seal by referring to the instructions for drum brakes in Chapter 7.
Clean the parts, check for wear and renew any which are faulty. The axle bearing is best checked when clean and dry. Renew the O-rings.
Key to Fig 10:18
1 Disc
2 Handbrake shoe and lining
3 Retaining spring
4 Handbrake cable
5 Cable tube
6 Spring
7 Handbrake expander struts
8 Anchor plate
Reassembling:
Fit the O-rings, sticking the large one round the bearing with some grease. Fit the backplate and anchor plate and tighten the bolts to 18 lb ft. Line up the marks and fit the hub. Tighten axle nut to 400 lb ft and fit a new splitpin.
Fit lower shoe and retaining spring, which is part 3 in FIG 10:18. Fit upper retaining spring. These are also clearly shown in FIG 10:20. Attach rear return spring to lower shoe, then to upper shoe. Mount it so that the coils slope towards the axle as shown by the black lines in the illustration. Pull on the upper shoe and insert in retaining spring. Fit front spring from the back of the shoes, then spread shoes apart and fit adjusting assembly. The toothed adjusting wheel must be uppermost on the righthand brake and underneath on the lefthand brake.
Fit the mechanical expander with the struts properly seated on the brake shoe studs. Fit slotted nut, line up hole and slot and fit new splitpin. Fit disc and check for runout. This is done by putting spacing washers under the wheel stud nuts and tightening them in diagonal fashion to a torque of 72 lb ft. Mount a dial gauge so that it touches the braking surface near the outer edge. Maximum runout is .20 mm (.008 inch). If excessive, try moving the hub round the axle splines to a new position. When checking, keep the axle pushed in towards the differential.
Fit the caliper and tighten the mounting bolts to 47 lb ft, using new spring washers. Fit brake pads in their original positions. Bleed the brakes (see Section 10:13). With car on ground, check transmission oil level and replenish if necessary. Adjust handbrake (see Section 10:2).
Removing and refitting oil deflector on hub:
It can be seen from FIG 10:19 that there is an oil deflector 8 fitted to hub 7. This catches any transmission oil which may pass seal 6 and drains it away to the outside. To remove the deflector, remove the hub and reduce the flare of the tube where it passes through the hub. Place two pieces of packing on the hub flange and lever off the old deflector with two screwdrivers.
Key to Fig 10:19
1 Clamping ring
2 Dust cover
3 Piston seal
4 Brake fluid
5 Piston
6 Oil seal
7 Wheel hub
8 Oil deflector
9 Brake disc
10 Handbrake shoe
11 Disc shroud
12 Hydraulic line
13 Brake caliper
14 Bleed valve
15 Retaining screw
16 Adjusting assembly
17 Return spring
18 Wheel bearing
19 Anchor plate
20 Return spring
21 Brake cable
22 Mechanical expander
FIG 10:20 Handbrake shoes on rear disc brakes, showing angular setting for return spring coils (black lines)
FIG 10:21 Bleeding the brake system, showing spanner on bleed valve, with tubing and fluid container
Fit a new deflector, inserting the drain tube in the hole in the hub. Secure a piece of steel tubing 130 mm long (5.12 inch), with an outside diameter of 55 mm (2.17 inch) and a bore of 52 mm (2.05 inch). Insert this in the deflector with the hub placed studs downwards under a press and push the deflector onto the hub boss. Using a conical punch, flare out the drainage tube where it emerges from the flange.
Discs will be found to wear with concentric grooves which are not detrimental to braking efficiency. Slightly damaged or worn discs may be refinished providing the thickness is not reduced by more than .50 mm (.020 inch). New front discs have a thickness of 10.3 to 10.5 mm (.406 to .413 inch) and new rear discs 9.8 to 10.0 mm (.386 to .394 inch). Machine discs only if absolutely necessary. Discard discs which show signs of cracking.
This will be necessary if any hydraulic connection has been disconnected during work on the braking system. This does not, however, apply to the pipe which connects the fluid reservoir to the master cylinder on 356C cars. The operation of bleeding the system may also cure such troubles as excessive pedal travel with a ’spongy’ feel, or if the brakes seem unbalanced. Complete draining during a major overhaul may call for two sequences of bleeding to ensure that all air has been removed.
Bleeding is a matter of forcing entrained air in the hydraulic fluid, through the pipes and out through the bleed valve fitted to each cylinder. The operation must be carried out on righthand drive cars in the following order:
1 Right rear wheel, outer bleed valve then inner valve (single valve, drum brakes).
2 Left rear wheel, outer bleed valve then inner valve (single valve, drum brakes).
3 Left front wheel, outer bleed valve then inner valve (upper, then lower valve, drum brakes).
4 Right front wheel, outer bleed valve then inner valve (upper, then lower valve, drum brakes).
Filling the system:
If the system is empty, open the first bleed valve in the preceding sequence by one-half of a turn. Depress the brake pedal slowly, close the valve and release the pedal. Repeat until fluid comes out through the tube attached to the valve (see FIG 10:21). Keep the reservoir topped up with fluid all the time and do not use fluid which has been ejected. Then bleed the brakes as follows:
Bleeding:
Fill the reservoir with recommended fluid such as ATE-BLAU (blue). Never use mineral oil or substitutes, as complete failure of the system will result. Keep the reservoir topped up at all times because air will re-enter the system if the ports into the master cylinder become uncovered.
Refer to FIG 10:21 and attach a length of tubing to the bleed valve as shown. Immerse the free end in a little clean fluid in a glass jar. Clear plastic tubing is useful because the air bubbles can be seen. Proceed as follows:
1 Use the sequence given at the beginning of this Section. Pump the brake pedal several times until it feels reasonably solid. Holding the pedal down, open the bleed valve about one-half of a turn and push the pedal right down. A second operator should be operating the valve and watching the tube. Air bubbles will almost certainly be seen to emerge from the tube. Keep the pedal down and close the valve. Release the pedal and repeat the operation.
2 When no more air bubbles emerge, keep the pedal down and finally close the valve. Remove the tube and refit the dust cap.
3 Repeat the procedure on the rest of the valves, taking care to keep the reservoir topped up at all times. Do not re-use fluid which has been pumped out of the system.
4 Apply the brake, pressing hard and getting a second operator to check all pipes and connections for leaks. The pedal should feel solid. If ’spongy’ there is still air in the system.
It is important to be very careful when topping up not to spill fluid on the car finish, as the fluid will remove it. Checks on fluid level in the reservoir for disc brakes must be made more frequently because the large pistons cause a greater increase in cylinder volume as the pads wear. Before taking the car for a road test, depress the pedal several times and always try the brakes at low speeds first.
The pull of the handbrake is transmitted through the front cable to a bellcrank. From there it pulls on a central cable which terminates in a beam to which the two cables are attached which go to the rear brakes. The beam is shown in FIG 10:22 (drum brakes) and FIG 10:6 (disc brakes).
Removal:
Jack up the car, remove rear wheels and rear brake drums. On drum brakes, remove shoes and unscrew bracket for handbrake cable from backplate. On disc brakes, release cable from expander as instructed in Section 10:11. Remove covering from front tunnel inside car and remove floorboard on the pedal side. Detach spring on cable coupling and unhook cables. Pull out rear cables backwards. Unscrew adjusting nuts arrowed in FIG 10:4 and pull cable out from the front. Open bonnet and remove spare wheel then remove inspection cover over steering gear.
The bellcrank is now visible. Unhook the front cable from the bellcrank. By removing two nuts the handbrake assembly may be removed.
The front cable may be detached from the handbrake by dismantling the assembly. When reassembling, the stop side (which is marked ’R’ on righthand drive cars) must face towards the handle and the hollow of the locking part must do the same. Working from the handle downwards, reassemble the stop first, followed by the spring, the locking part and the shim. When inserting the assembly, the handle must be vertical, the ’R’ must be on the stop and the notch on the locking part must be visible in the hole. Remember to fit the sealing rubbers.
FIG 10:23 Flexible hose to front drum brake (lower left). Arrow points to pipe connecting cylinders together
Before attaching the brake cable, preload it about half a turn so that, when released, the handbrake handle always returns automatically to the horizontal or initial position. Check that the adjusting sleeves and nuts move freely, clean the cable guides and fill them with grease. Check new cables for correct length.
After reassembly, adjust the foot- and handbrakes as described in Section 10:2. Check that the system works correctly
Flexible hoses:
These are an important link between the hydraulic pipelines and the brakes and must be checked regularly for signs of deterioration. If they are chafed, cracked or swollen they must be renewed at once.
Hoses must be long enough to avoid stretching from movements of the suspension. They must also be positioned so that they cannot chafe during such movements and must not be twisted during installation. Make sure that there is no contact with petrol, paraffin or mineral oils. The correct method of removing hoses is as follows:
1 Start at the inner end and release the metal pipeline union nut.
2 Remove clamping spring from bracket and pull out hose (see left in FIG 10:23).
3 Unscrew hose from backplate or caliper.
This sequence also applies when a hose is detached from the distributing connection to the rear brakes. The whole object is to prevent twisting of the hose itself.
Installation of the hoses is made in the reverse order, checking that steering and suspension movements cannot strain or chafe them. Finally, bleed the system as in Section 10:13.
As there is a chance that rear brake hoses may hit the heater tubes during rear suspension movements, check that the hose brackets are correctly fitted on the axle tubes. They must be inclined at 45 deg., with the clamping bolt to the rear and uppermost. The hose bracket will then hang down at 45 deg in the front.
The stainless steel brake pipelines have an outside diameter of 4.75 mm (.187 inch) and a wall thickness of .72 mm (.031 inch). If tubes need renewal, use the same type of tubing and have the ends flared by an agent equipped with tool P.48. Make sure that the union nuts are on the tube before flaring. Apply a drop or two of brake fluid to the pipe flange before tightening the union.
(a) ’Spongy’ pedal
1 Leak in system
2 Worn master cylinder
3 Leaking wheel cylinders
4 Air in the fluid system
5 Linings not firmly bedded to shoes
6 Insufficient fluid in reservoir
(b) Excessive pedal movement
1 Check 1, 4 and 6 in (a)
2 Excessive lining or pad wear
3 Too much free travel of pedal
4 Check valve in master cylinder defective
5 Clearance needs adjusting
6 Worn brake drums
7 Missing or worn rubber stop
(c) Brakes grab or pull to one side
1 Distorted discs or drums
2 Wet or oily pads or linings
3 Brake backplate loose
4 Worn suspension or steering connections
5 Mixed linings of different grades and thicknesses
6 Uneven tyre pressures
7 Broken shoe return springs
8 Seized piston in wheel cylinder
9 Loose caliper mountings
(d) Pedal needs pumping to get braking
1 Air in system
2 Check valve in master cylinder faulty
3 Weak spring in master cylinder
4 Insufficient fluid in reservoir
(e) Brakes get hot when not used
1 Small hole between reservoir and master cylinder blocked by main cup
2 No free play in master cylinder pushrod
3 Weak or broken shoe return springs
4 Seized wheel cylinder pistons
5 Rubber cups swollen due to incorrect brake fluid
6 Footbrake adjustment too close
(f) Pedal easily depressed, no resistance
1 Check (d)
2 Burst flexible hose or steel pipes
3 Master or wheel cylinder cups defective
(g) High pedal pressure but poor braking
1 Check 2, 5 and 8 in (c)
2 Brake linings or pads burnt or glazed through overheating
