CHAPTER 6 - HYDRAULIC BRAKES

Chapter 6 - Hydraulic Brakes

173

GENERAL INFORMATION

Service intent: If the master cylinder or brake caliper fails under warrantable conditions, replace it as a com-plete unit. Rebuild kits may eventually become avail-able through Cub Cadet, but failures in the initial two years of production will be serviced primarily with replacement master cylinders or calipers.

Scope: This chapter covers the hydraulic service brakes. The vehicle also has a cable operated parking brake attached to the transfer case. The parking brake is completely independent of the service brake, and it is covered in the CVT and Transfer Case chapter of this manual.

Brake fluid maintenance:

• Brake fluid is hygroscopic, meaning that it absorbs water and holds it in suspension.

• Eventually, the fluid will absorb enough water that the water will begin corroding components.

• DOT-3 or DOT-4 brake fluid should be flushed and replaced every two years to prevent dam-age to the master cylinder and the brake cali-pers.

• Treating brake fluid as a periodic maintenance item will dramatically extend the life of the brake calipers.

The master cylinder is mounted near the base of the structure that supports the steering column. See Figure 6.1.

Figure 6.1

Master cylinderreservoir

Left frontspring and damper unit

Checking the fluid: See Figure 6.2.

NOTE: The reservoir is translucent, so the fluid can be checked without removing the cover.

1. If it is necessary to add fluid, clean thoroughly around the cover before removing it.

2. Rotate the cap until the lock tabs are at the 2:30 and 7:30 positions, as seen from the front of the vehicle, then lift upward to remove it.

NOTE: Use only DOT-3 or DOT-4 fluid from a sealed container.

CAUTION: It should not be necessary to add fluid in the course of normal operation. If the fluid level goes down, there is a leak that must be identified and repaired before the vehicle is used.

Figure 6.2

Notches

Lock tabs

CHAPTER 6 - HYDRAULIC BRAKES


174

The brake hydraulic system is divided into two circuits: front and rear. See Figure 6.3.

• The bore of the master cylinder contains two pis-tons on a common shaft.

• The front piston powers the front brakes through the front fitting on the master cylinder. The rear piston powers the rear brakes through the rear fitting on the master cylinder.

• The reservoir is partitioned into two sections. Each section feeds one port in the master cylin-der bore. The forward section feeds the front pis-ton in the master cylinder. The rear section feeds the rear piston in the master cylinder.

• Because all four wheels have disc brakes, hydraulic action is direct. There are no compen-sators, balancers, or apportioning valves.

BRAKE PUSH ROD ADJUSTMENT:

• In the course of normal operation, brake adjust-ment should not be necessary.

• If brake adjustment does become necessary, check the system for wear, damage, and leaks.

3. To make an adjustment: loosen the brake cle-vis jam nut using a 13mm wrench, while holding the brake actuator rod with a 6mm wrench. See Figure 6.4.

4. Rotate the brake actuator rod in or out of the brake yoke to make adjustments, then lock in the adjustment using the jam nut.

5. The linkage is correctly adjusted when the bot-tom of the pedal arm is even with the seam where the top of the kick panel meets the bottom of the under-dash support. 1/8”-1/4” (3.2-6.4mm) free play is normal. See Figure 6.5.

Figure 6.3

Front chamber Rear chamber

Front wheelbrake circuit

Rear wheel brake circuit

Front of vehicle

Figure 6.4

Clevis pinBrake push rod

Jam nut

Yoke

Figure 6.5

Pedal arm

Under-dash support

Seam

Kick panel


175

BRAKE FLUID FLUSHING AND BLEEDING

The brake fluid should be flushed and bled every two years.

The brake fluid should be bled any time the pressur-ized portion of the hydraulic system has been opened. If only one side of the system has been opened (front or rear) then only that side needs to be bled. In general practice though, it is usually convenient to bleed the entire system

To bleed the brakes:

1. Lift and safely support the vehicle as described in the Introduction chapter of this manual. See Figure 6.6.

2. Tilt the hood forward to reach the master cylin-der. The hood may be removed, at the techni-cian’s discretion. See Figure 6.7.

Figure 6.6

Figure 6.7

Keep master cylinderreservoir filled to ”Full”

3. Clean around the cap, and confirm that there is sufficient fluid in the reservoir. Top-up if neces-sary.

NOTE: Be careful of spilling brake fluid on painted surfaces. While the powder-coat pro-cess used on the frame of the Cub Cadet utility vehicle line is relatively resilient to brake fluid, surrounding surfaces may not be.

CAUTION: If the brake fluid level is low, identify and repair the leak before operating the vehicle.

4. Remove the wheels using a 3/4” wrench.

NOTE: Because the front and rear circuits are independent, they can be bled independently. It is most effective to start at the longer side of each circuit: the passenger side.

5. Connect a clear hose and catch bottle to the first caliper that is to be bled. See Figure 6.8.

• There are two bleeder screws on each caliper: one near the top, and one near the bottom.

• Bleeding to purge air is best done at the top fit-ting.

• When doing a periodic maintenance flush, a small amount of fluid may be flushed from the bottom fitting to remove any settled residue or moisture.

6. Open the bleeder screw using a 1/4” wrench.

NOTE: It may be necessary to loosen, rotate, and re-tighten the banjo fitting slightly for wrench clearance. Use a 1/2” wrench on the banjo bolt.

• The system should gravity-bleed without any additional pressure.

Figure 6.8

Upper bleed screw

Lowerbleed screw

Fluid catch-bottle


176

7. To bleed under pedal-pressure: See Figure 6.9.

7a. Have an assistant apply firm pressure to the brake pedal. It may be necessary to pump-up pressure, but the pedal applica-tion should be steady for bleeding.

7b. Loosen the bleed screw, watching for bubbles or contaminants in the stream of fluid that passes through the clear tube. The pedal will go down as fluid comes out.

7c. Tighten the bleed screw before the assis-tant lifts their foot from the pedal.

7d. Repeat as necessary until the fluid runs clear.

8. Repeat the bleeding process on the driver’s side brake caliper to complete bleeding the circuit.

9. Repeat the bleeding process on the remaining circuit to complete bleeding the system.

10. Check the pedal for firmness after bleeding.

11. If the system is full and properly bled, yet the pedal is spongy, find and repair the problem before operating the vehicle.

NOTE: Though not shown in the Illustrated Parts List, brake caliper bleed screws are available as service parts under the part number: 759-04127.

NOTE: If it is suspected that air is trapped in the master cylinder it may be necessary to bleed the master cylinder.

12. The procedure for bleeding at the master cylin-der closely follows the procedure use to bleed the individual wheels. Instead of loosening the bleeder screws at each caliper the Banjo bolts at the base of the master cylinder are loosened to allow the air trapped to escape. See Figure 6.10.

13. If the pedal is firm:

13a. Attach the wheels, tightening the lug nuts to a torque of 75 ft-lbs. (102N-m).

13b. Lower the vehicle to the ground.

13c. Test the operation of the brake system in a safe area that is free of hazards, obsta-cles, and by-standers before returning it to service.

Figure 6.9

Apply pressure

Figure 6.10

Banjo fittings

Banjo bolts

Copperwashers

Tighten banjo bolts to 20-22 ft-lbs (27-30N-m)


177

BRAKE SYSTEM DIAGNOSIS

Soft Pedal

• Leakage: Make a visual inspection of the com-plete system. Pay attention to the back of the master cylinder, the calipers, and all the connec-tion points in the system. Leaks are sometimes easier to find before the vehicle is cleaned. Check the master cylinder fluid level. If both sides of the reservoir are low, the leak may be where the push-rod enters the back of the mas-ter cylinder. If only one side of the reservoir is low, use that information to direct the search. Tracking fluid up from a puddle can also assist in finding a leak. A clean cap on the reservoir is an indication that the operator may have added, or at least checked, the fluid level.

• The master cylinder should be capable of pro-ducing about 1,500 psi.(103 Bars) of hydraulic force. If there is no leakage, but the pedal is soft, there may be blow-by at the internal seals in the master cylinder bore. If the shop is not equipped with pressure gauges to connect to the master cylinder, it is necessary to use the process of elimination. If none of the remaining causes in the section are causing the problem, it is likely to be the master cylinder.

• Caliper frozen on slide pins: After a long period of dis-use or extremely gentle use, the calipers may have become stuck on the slide pins by corrosion or debris. When pressure is applied to the piston in the cal-iper, the inside pad contacts the rotor, and the body of the caliper normally slides in the oppo-site direction, pulling the second brake pad against the outside of the brake rotor. If the caliper does not slide, the force applied to the piston will bow the caliper bracket and may bow the rotor. The “giving” and springing-back of the metal parts will cause a soft pedal. This situation is easily identified by visual inspection while an assistant works the brake pedal.

• Air in the system: Unless caused by leakage, this condition will follow any service that requires the opening of the hydraulic system. The sys-tem should be bled after any such repair. It bleeds easily, and should not present an obsta-cle for most technicians.

• High temperature fade: Results from boiling fluid under extremely heavy use. This should not be an issue in any reasonable operation of the vehicle.

Firm pedal but poor brake performance

• Friction surface problems are the most likely cause of this situation. Clean any liquids off the brake rotor, and identify the source of those liq-uids. If the source is an oil or gear lube leak, repair it to prevent reoccurrence. If the pads are contaminated, replace them.

• If the situation is accompanied by a screeching noise, and comes-on suddenly, a small stone may have become trapped between the brake pad and the rotor. Loosen or remove the cali-per to dislodge the stone before it damages the rotor. This is a highly unusual problem, but it can occur.

• After many hours of use, the pads will wear. Worn pads will allow the brake pad wear indica-tors to touch the rotors, causing a squeaking sound. This sound is a normal indication that the brakes need service.

Pedal pulsation

• Warped brake rotor. Check rotors for run-out using a dial indicator, Once the warped rotor is identified, replace it.

• Variations in friction around the surface of the rotor can cause similar stopping characteristics to a warped rotor, but without actual pulsation of the pedal. This issue is usually caused by rust spots or foreign material on the surface of the rotor. These symptoms will usually go away with use.


178

Brake drag / pulling (if at front caliper)

• Caliper frozen on slide pins: After a long period of dis-use or extremely gentle use, the calipers may have become stuck on the slide pins by corrosion or debris. When pressure is applied to the piston in the cal-iper, the inside pad contacts the rotor, and the body of the caliper normally slides in the oppo-site direction, pulling the second brake pad against the outside of the brake rotor. If the caliper is frozen on the pins, the inboard brake pad will drag on the inner surface of the brake rotor. Accelerated wear of the inboard pads and rotor surface of any caliper are a tell-tale sign of this condition.

• Caliper piston stuck in bore. This is an unusual problem, but it can happen on any disc-brake design. Accelerated wear of both pads on any single rotor is the primary indicator. If the vehicle is operated for any length of time, the rotor surfaces will be blued from over-heating.

• Damaged brake line. After many years of use, it is possible for the interior lining of some flexible hoses to disintegrate or “implode”. This will cause sluggish action in both directions. The caliper(s) on the effected wheel(s) will apply slowly and release slowly. Typical customer complaint if a front brake line is effected will be that the steering wheel pulls in one direction while the operator applies the brakes, but pulls in the opposite direction when they accelerate away from a dead stop.

• Master cylinder / brake pedal not returning. This would most likely result in brake drag accel-erated wear and blued rotors at all four wheels. Check for bound pedal linkage. Do not over-look the possibility that the operator may be rest-ing their left foot on the pedal.

AT-WHEEL COMPONENTS

The brake calipers (single-piston, floating) are identi-cal front to rear, and the pad replacement method is identical as well. See Figure 6.11.

Each brake pad has an anti-squeal plate bonded to the back side of the pad. Original thickness of the friction material is roughly .156” (4mm). See Figure 6.12.

• The anti-squeal plate is attached by adhesive and clips.

• The clips extend roughly .020” (.50mm) over the friction surface side of the pad, and act as an audible wear sensor when the friction material is worn to less than .020”

• Replace the pads when the friction material thickness is less than .040” (1mm).

Figure 6.11

Front brake caliper

Brake pads

Brake rotor

Figure 6.12

Brake pad

Anti-squeal plate


179

Brake Pads: The brake caliper must be removed to replace the brake pads.

1. Remove the C-clips from the mounting pins using a small screwdriver. See Figure 6.13.

2. Loosen the top bleed screw 1/2 turn using a 1/4” wrench.

3. Remove the mounting pins using a 3/8” allen wrench. See Figure 6.14.

4. As the mounting pins are withdrawn, the pads will come free of the caliper.

Figure 6.13

C-clips

Figure 6.14

Mounting pins

Bleed screws

5. When the mounting pins are completely removed, the caliper will come free of the bracket on the hub. See Figure 6.15.

CAUTION: Support the caliper. Do not allow it to hang on the flexible hydraulic line. While the line will hold thousands of P.S.I. of internal pres-sure, it was not designed to handle tensile loads.

6. Use a C-clamp to drive the piston back into the caliper. See Figure 6.16.

• Retracting the piston will make room for the additional thickness of the new pads.

• Be aware that driving one piston in, with the bleeder closed, will displace fluid. That fluid may return to the reservoir or force the piston out of another dismounted caliper. Open the bleed screw to avoid these issues. Be prepared to catch any expelled fluid.

Figure 6.15

Caliper removed

Figure 6.16

Brake piston


180

7. Check the slide bushings. See Figure 6.17.

• The slide bushings should be clean, and free to slide in the mounting bores of the caliper.

• O-rings provide a seal between the bushings and the caliper.

• Uneven pad wear may indicate that the caliper is not sliding as designed, and the slide bushings require attention.

• On assembly: lubricate the O.D. of slide bush-ings or the I.D. of the bore with a high tempera-ture synthetic grease that is meant for use on brake calipers. Typical of these products is Versachem Part Number 26111, available through NAPA® as Item #BK7653072.

8. Check the brake caliper bracket for damage or loose hardware. See Figure 6.18.

9. Check the brake rotor as described in the follow-ing section of this manual before reinstalling the caliper. Replace the rotor if necessary.

10. Installation notes: brake caliper See Figure 6.19.

NOTE: A brake pad service kit is available as 959-04116. This kit is not shown in the Illus-trated Parts List. The kit consists of: two brake pads, two slide pins, and two retaining rings. This will service a single wheel. Two kits are required for an axle. The same kit is used for front and rear wheels

10a. If brake rotor has been removed, install the brake rotor.

10b. Clean any grease, oil, or fingerprints from the brake rotor.

10c. Apply a very small amount of anti-seize compound to the shoulders of the caliper mounting bolts (slide pins).

10d. Position the caliper on the caliper bracket, and insert the slide pins just far enough to hold the caliper in place.

10e. Slip the piston-side brake pad into place, pushing the slide pins through far enough to hold the piston-side pad.

10f. Slip the outside pad into place, and com-plete the installation of the slide pins: push them in until the threads engage, then tighten them to the specified torque using a 3/8” allen wrench.

10g. Install the C-clips that secure the brake pads. If there is any question of the condi-tion of the C-clip replace it with a new one.

Figure 6.17

Slide bushing

O-ring seals

Figure 6.18

Brake caliperbracket (rotorremoved for visibility)

If removed, apply thread-locking sealant such as Loctite® 262 (red)to threads, and tightento a torque of 22-26 ft-lbs (30-35 N-m)

Figure 6.19

Slide pins

Caliper

Inside pad


181

11. Bleed the hydraulic system, if necessary.

12. Install the wheels, and lower the vehicle to the ground.

13. Test-drive the vehicle in a safe area before returning it to service.

Torque specifications for Brake Pads section:

* Apply anti-seize compound

** Apply releasable thread locking compound

Item ft-lbs N-m

Caliper slide pins* 22-26 30-35

Caliper bracket bolts** 22-26 30-35

Lug nuts 65-75 88-102

Component Repair: Brake calipers

1. Remove the brake caliper as described previ-ously in the AT-WHEEL COMPONENTS section of this manual.

2. Remove and inspect the slide bushings that go over the mounting pins. See Figure 6.20.

NOTE: Clean any light corrosion with a Scotch-Brite® pad or similar product.

3. Upon removal of the slide bushings remove and inspect the O-rings. Replace any O-ring that shows signs of wear. See Figure 6.21.

4. Secure the caliper in a vise making sure not to damage the casting or distort the bore.

Figure 6.20

Brake caliper

Slide bushings

Figure 6.21


182

5. Remove both bleeder screws with a 1/4” wrench. See Figure 6.22.

6. Drive the piston out of the bore using hydraulic pressure, a screw, or a drift through the hydrau-lic port. See Figure 6.23.

7. With the piston removed from the bore, the square section O-rings can be removed from their grooves in the bore. See Figure 6.24.

NOTE: The piston is symmetric, and closed at both ends.

8. Inspect the bore of the brake caliper.

• If the bore is undamaged, clean it thoroughly and continue with assembly.

• If the bore is slightly worn or scored, it may be lightly dressed with emery cloth.

• If the bore is substantially worn or heavily dam-aged, replace the caliper.

NOTE: Because the sealing surface is on the piston, not the bore, piston wall finish is more critical than bore wall finish.

9. Clean all parts that are to be assembled.

9a. Initial cleaning may be done with Stoddard solvent.

9b. Final cleaning should be done using hot soapy water (dish washing detergent is suitable), a nylon brush and a nylon bore-bush.

9c. Rinse and dry all parts thoroughly.

Figure 6.22

Bleeder screws

Figure 6.23

Figure 6.24

Caliper housing Piston bore

O-ringsin bore


183

10. Assemble the caliper using the new parts con-tained in the kit, installed as described in the dis-assembly process. See Figure 6.25.

11. Lubricate the bore of the caliper with brake fluid. Lubricate the piston with brake fluid or a suitable brake assembly lubricant such as Sil-Glyde™, available from NAPA® auto parts (p/n:765-1351).

CAUTION: Do not get brake fluid on painted sur-faces. Brake fluid dissolves or damages many types of paint.

12. Install the new square section O-rings into the grooves inside of the bore.

Figure 6.25

Piston

O-rings

Caliper housing

13. Carefully insert the piston into the bore of the cylinder. See Figure 6.26.

14. Install the bleeder screws.

15. Lubricate and install the o-rings and slide bush-ings

NOTE: On assembly: lubricate the O.D. of slide bushings or the I.D. of the bore with a high tem-perature synthetic grease that is meant for use on brake calipers. Typical of these products is Versachem Part Number 26111 available through NAPA® as Item #BK7653072. Sil-Glyde™ is also a suitable lubricate.

16. Install the caliper as describe in the Brake Pad section on this manual.

17. Bleed the hydraulic system

18. Install the wheel, and lower the vehicle to the ground.

19. Test drive the vehicle in a safe area before returning it to service.

Figure 6.26

Insert piston into bore


184

Brake Rotors

Examine the brake rotors. Original thickness is .1875” (4.76mm). See Figure 6.27.

The rotors merit replacement if:

• Warpage exceeds .020” (.50mm) total indicated run-out (T.I.R.)

• The friction surface is deeply scored, pitted, or erupted.

• Total thickness is less than .125” (3.175mm).

The brake rotors are very similar front to rear, and the rotor replacement method is identical.

1. Remove the brake caliper as described in the Brake Pads section of this manual. See Figure 6.28.

2. Remove and discard the cotter pin that secures the axle nut. See Figure 6.29.

3. Remove the axle nut and the heavy flat washer behind it using a 32mm wrench.

4. Affix an automotive hub puller to the axle and hub assembly. See Figure 6.30.

Figure 6.27

Dial indicatormounted tosteering travel stop bolt

Figure 6.28

Brake rotor

Figure 6.29

Cotter pin

Axle nut

Figure 6.30

Hub puller


185

5. Use the puller to draw the hub and rotor assem-bly off of the axle and hub carrier (upright) assembly. See Figure 6.31.

6. Once removed from the vehicle, the rotor can be separated from the hub using a 7/16” wrench. See Figure 6.32.

Figure 6.31

Figure 6.32

Wheel hub

Brake rotor

7. Installation notes: brake rotor

7a. Inspect the axle splines, hub splines, wheel studs, and axle threads before assembly. Replace any suspect compo-nents.

7b. Apply a small amount of thread locking compound such as Loctite® 262 (red) to the bolts that hold the brake rotor to the hub, prior to assembly. Tighten the bolts to a torque of 10 ft-lbs (14 N-m).

7c. Apply a small amount of anti-seize com-pound to the hub splines before installa-tion.

7d. Install the brake rotor hub, washer, and axle nut

7e. Tighten the axle nut to a torque of 150-165 ft-lbs. (203-224 N-m) and secure with new 5/32” x 1.25” (4mm x 32mm) cotter pin.

7f. Install the brake caliper as described in the Brake Pads section of this manual.

NOTE: The axle nut torque sets the pre-load on the wheel bearings. Improper tightening of the axle nut will decrease wheel bearing life.

8. Bleed the hydraulic system if necessary.

9. Install the wheels, and lower the vehicle to the ground.

10. Test-drive the vehicle in a safe area before returning it to service.

* Apply anti-seize compound

*** Apply permanent thread-locking compound

Item ft-lbs N-m

Caliper slide pins* 22-26 30-35

Brake rotor to wheel hub bolts***

10 14

Axle nut 150-165

203-223

Lug nuts 65-75 88-102


186

MASTER CYLINDER

Before condemning a master cylinder, check the fol-lowing:

• Leaking lines or fittings

• Leaking caliper piston seals

• Binding caliper slide bushings

• Pedal linkage binding or mis-adjustment

General indications: Blow-by

• If black material has accumulated in the reser-voir, that is an indication that the seals within the master cylinder are deteriorating. This condition does not automatically condemn a master cylin-der, but should be considered a wear indicator.

• If the rest of the hydraulic system is sound, yet the pedal sinks or is soft under pressure, the master cylinder is the most likely culprit.

• A master cylinder with blow-by may have bad internal seals, but may not leak fluid externally.

General indications: leakage See Figure 6.33.

A master cylinder with a confirmed leak around the actuator rod that enters the end of the cylinder has failed and must be replaced before further use of the vehicle.

To Replace a Master Cylinder:

1. Open and remove the hood for easy access to the master cylinder:

1a. Tilt the hood forward

1b. Disconnect the wires from the headlights

1c. Disconnect the hood check cables using a 3/8” wrench.

1d. Remove the hairpin clips that hold the hood onto the hood support rods.

1e. Slide the hood to the left of the vehicle and remove it.

2. Lift and safely support the vehicle.

3. Remove the wheels using a 3/4” wrench.

4. Remove the left front spring and damper unit using a pair of 3/4” wrenches. See Figure 6.34.

NOTE: When the suspension is at full droop, the spring and damper units are not under load. They can be safely unbolted and removed with-out any additional compression devices, unless they have been modified or adjusted to increase travel or spring rate.

Figure 6.33

Look forleakage

Figure 6.34

Left frontspring and damper unit

Upper control arm


187

5. Remove the left front fender from the vehicle: See Figure 6.35.

6. Remove the 3 sets of nuts and bolts attaching the fender to the frame uprights using a pair of 7/16” wrenches.

7. Remove the 3 self tapping screws attaching the fender to the lower portion of the frame using a 1/2” wrench.

8. Pull the fender out of the channels (frame uprights) that locate it, and lift it away from the vehicle.

9. Loosen the jam nut using a 1/2” wrench.

10. Remove the hairpin clip and clevis pin that con-nect the brake yoke to the brake pedal arm. See Figure 6.36.

10.1. Place a catch pan to collect any leaking fluid.

Figure 6.35

Left frontfender

Self-tapping screws

Nuts / bolts

Figure 6.36

Clevis pin

Push rod

Jam nut

Yoke

11. Disconnect the brake lines using a 1/2” wrench. See Figure 6.37.

NOTE: The front circuit is connected with a 90 degree elbow. The rear circuit is connected with 45 degree elbow.

NOTE: Inspect the copper washers sandwiching the fitting on the banjo bolt. If the sealing face of any washer is not indented, it may be reused. It is recommended to replace the washers when-ever the banjo fitting is disconnected.

12. Remove the master cylinder: See Figure 6.38.

12a. First loosen, then remove the mounting bolts using a pair of 1/2” wrenches.

12b. Pivot the master cylinder up at the front to clear the frame, then lift it out of the vehi-cle.

Figure 6.37

Copper washers

front rear90 degree 45 degree

Figure 6.38


188

13. Installation notes: Mounting the master cylinder See Figure 6.39.

13a. Apply a small amount of thread locking compound such as Loctite® 242 (blue) to the bolts that hold the master cylinder to the frame. Insert the bolts into the master cylinder prior to setting it in place.

13b. Secure the master cylinder to the frame with a pair of 1/2” wrenches.

13c. Reconnect the brake actuator rod to the brake pedal arm with the clevis pin and new cotter pin.

14. Installation notes: connecting the master cylin-der:

14a. If bench bleeding tubes are available, install them in a loop from the outlet ports on the bottom of the master cylinder to the reservoir.

14b. Add brake fluid to the reservoir, and pump the brake pedal until fluid flows from the bench bleeder tubes without bubbles.

14c. Carefully disconnect the bench bleeder tubes one at a time and reconnect the hydraulic lines.

14d. Tighten the banjo bolts to the specified torque.

15. Bleed the entire brake hydraulic system, starting at the furthest point of each circuit:

• Check for leaks and pedal feel.

16. Final assembly:

16a. Install the front fender

16b. Install the front spring and damper unit.

16c. Install the wheels

16d. Lower the vehicle to the ground

16e. Test drive the vehicle in a safe area

16f. Install the hood

Torque specifications for master cylinder installation:

Figure 6.39

Mounting bolts

Item ft-lbs N-m

Spring and damper unit bolts

43-64 58-87

Banjo bolts 20-22 27-30

Lug nuts 75 102


189

Pedal Linkage

The pedal pivots on a pair of thin-wall split plastic bush-ings. A dry graphite or PTFE-based spray lube may extend the life of the bushings.

To replace the bushings:

1. Remove the left front fender, as described in the To Replace a Master Cylinder section of this chapter.

2. Remove the hairpin clip and clevis pin that con-nect the brake yoke to the brake pedal arm. See Figure 6.40.

3. Remove the shoulder bolt that supports the brake pedal arm using 3/4” and 9/16” wrenches.

4. With the bolt removed, the pedal can be pulled out of the bracket that it mounts to. See Figure 6.41.

Figure 6.40

Brake yoke

Brake pedal arm

Clevis pin

Figure 6.41

Bracket

Bushing

Brake pedal arm

5. Once the brake pedal is loose, the bushings can be easily pried-out and replaced.

6. To remove the brake pedal arm from the vehicle: See Figure 6.42.

6a. Unbolt the kick panel from the under-dash support using a pair of 1/2” wrenches.

6b. Loosen the screws that connect the kick panel to the floor using a 3/8” wrench.

7. Install the brake pedal arm by reversing the removal process.

8. Test-run the vehicle in a safe area before return-ing it to service.

Figure 6.42

Under-dash support

Kick panel

Unbolted here


190

Component Repair: Master Cylinder

NOTE: Master cylinder repair will not be avail-able during the initial year of production.

• Pending availability, this section of the manual will provide guidance repairing the master cylin-der.

• If repair parts are not available, this section will help the technician further understand the work-ings of the master cylinder, which may aid in the diagnosis of a brake hydraulic problem.

1. Remove the master cylinder from the vehicle, as described in the To Replace a Master Cylinder section of this manual. See Figure 6.43.

2. Drain and properly dispose of any residual fluid.

3. Remove the 2 shouldered screws that secure the plastic reservoir. See Figure 6.44.

4. Remove the busings that seal the reservoir to the cylinder housing. See Figure 6.45.

5. Remove the push rod.

5a. Mark the threads on the push rod to main-tain brake adjustment.

5b. If the jam nut was not loosened in the removal process, hold the push rod with a 1/4” wrench, or brace the yoke using a length of 5/16” round stock, and loosen the nut using a 1/2” wrench. See Figure 6.46.

5c. Remove the yoke and jam nut.

Figure 6.43

Master cylinder, complete

Screws securing reservoir

Figure 6.44

Cap Reservoir

reservoir and master cylinderBushings create seal between

Figure 6.45

Push rod

Reservoir seal bushings

Figure 6.46

Yoke

Jam nut

Flat


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5d. Remove the dust seal from the push rod end of the master cylinder. See Figure 6.47.

5e. Carefully fixture the master cylinder in a vice. Do not clamp it tightly enough to dis-tort the bore. Do not damage any of the threaded features or sealing surfaces.

5f. Move the push rod aside to gain access to the retaining ring that holds it in the bore. Remove the retaining ring. See Figure 6.48.

5g. Withdraw the push rod, retaining ring, and retaining plate from the bore.

NOTE: The rear piston assembly is lightly spring loaded. It should extend slightly from the bore of the cylinder under its own spring pressure.

Figure 6.47

Dust seal

Match mark for jam nut

Figure 6.48

Retainingring

Push rod

6. Remove the rear piston and spring from the master cylinder bore. See Figure 6.49.

7. Remove the master cylinder from the vise and gently rap it, (bore side down) on a wood-topped work bench to dislodge the front piston. See Figure 6.50.

Figure 6.49

Rear piston assembly

Figure 6.50

Rear piston(Near open end of cylinder)

Front piston(Near blind endof cylinder bore)


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8. Install the repair kit components on the rear pis-ton:

8a. Carefully fixture the front piston in a vice, gripping it by the necked-down section of the piston.

8b. Remove the shouldered screw that secures the transfer cup, transfer spring, and spring seat, to the rear piston using a phillips head screwdriver. See Figure 6.51.

8c. Remove the power seal and flat washer from the spring end of the rear piston.

8d. Remove the make-up seal from the rear end of the rear piston. See Figure 6.52.

NOTE: The open side (lip) of both seals faces the spring end of the rear piston. The makeup seal is different from the power seal. The makeup seal has a secondary lip near the closed (rear) side of the seal.

9. Disassemble the front piston:

9a. Carefully pry the return spring and spring seat off of the barb at the front end of the front piston. See Figure 6.53.

Figure 6.51

Transfer cup

Transfer spring

Spring seat

Figure 6.52

Rear piston

Makeup seal

Figure 6.53

Spring seatReturn spring


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9b. Remove the power seal and flat washer from the front end of the front piston. See Figure 6.54.

9c. Remove the isolator seal from the rear end of the front piston. See Figure 6.55.

9d. Remove the makeup seal from the second seal land in from the rear end of the front piston.

NOTE: The open side (lip) of the power seal and the make up seal both face the spring (front) end of the front piston. The open side (lip) of the isolator seal, which is located at the rear end of the front piston, faces the rear of the piston.

Figure 6.54

Front piston

Flat washer

Power seal

Spring seat

Make-up portsin flange behind flatwasher aresealed underload. On return, theflat washer liftsoff the ports, allowing fluid transfer

Figure 6.55

Isolator seal Makeup seal

10. Inspect the bore of the master cylinder.

• If the bore is undamaged, clean it thoroughly and continue with assembly.

• If the bore is slightly worn or scored, it may be honed using a BRM® flex-hone according to the manufacturers instructions.

11. Clean all parts that are to be assembled.

11a. Initial cleaning may be done with Stod-dard solvent.

11b. Final cleaning should be done using hot soapy water (dish washing detergent is suitable), a nylon brush and a nylon bore-bush.

11c. Rinse and dry all parts thoroughly.

12. Assemble the pistons using the new parts con-tained in the kit, installed as described in the dis-assembly process.

NOTE: Use a small amount of thread locking compound such as Loctite® 242 (blue) on the shouldered screw that fastens the transfer spring, cup, and spring seat to the rear piston.

13. Lubricate the bore of the master cylinder with brake fluid. Lubricate the pistons with brake fluid or a suitable brake assembly lubricant such as Sil-Glyde®, available from NAPA® auto parts (p/n:765-1351).

CAUTION: Do not get brake fluid on painted sur-faces. Brake fluid dissolves or damages many types of paint.

14. Carefully insert the front piston, spring end first, into the bore of the cylinder.

15. Fixture the master cylinder into a vise as was done for disassembly.

16. Carefully insert the rear piston, spring end first, into the bore of the cylinder.


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17. Compress the springs, pushing the pistons into the bore using the push rod. See Figure 6.56.

18. Secure the push rod and retaining plate by installing the snap ring.

NOTE: Use a new snap ring if the original shows signs of stress.

19. Install the dust seal over the push rod.

20. Install the jam nut, and yoke to the position marked in the disassembly process.

21. Lubricate and install the bushings that seal the reservoir to the master cylinder, and secure the reservoir using the phillips head screws.

22. Install the master cylinder in the vehicle as described the MASTER CYLINDER section of this chapter.

22a. Bleed the brakes as described in the BRAKE FLUID FLUSHING AND BLEED-ING section of this chapter.

22b. Test the operation of the braking system in a safe place before returning the vehicle to service.

Figure 6.56

Push rod

Retaining ring

Retainer plate

Rear piston

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CHAPTER 6 - HYDRAULIC BRAKES