Online Guide and Manuals

Brake system is hydraulically actuated, using a tandem master cylinder and on models equipped with the 2000 cc engine, a power brake unit. All models are equipped with disc brakes on the front wheels and drum brakes on the rear wheels. Front disc brakes consist of a rotor and single piston, floating caliper assembly. Rear brakes are self-adjusting, leading-trailing shoe/drum type, actuated by a dual piston wheel cylinder. Parking brake is cable actuated, operating on the rear wheel brake assemblies. All models use a combination valve to control pressure on rear wheels.

Front disc brakes are self-adjusting, therefore, no adjustment in service is required.

Rear drum brakes are self-adjusting, therefore, no adjustment is necessary.

Adjust pedal height (distance front top of brake pedal to toe board) to specifications by moving pedal stopper (stop light switch). Pedal height should be as indicated. After pedal height is adjusted, loosen push rod lock nut and adjust free play as indicated.

                            Pedal Height & Free Play Adjustment

Application                         Pedal height                         Fee Play

                                            In. (mm)                             In. (mm)

Arrow

   Power Brakes.................  6.9-7.1..............................  .4-.6

                                          (175-180)                             (10-15)

   Without Power Brakes....  6.5-6.7..............................  .4-.6

                                          (165-170)                             (10-16)

Colt..................................... 6.4-6.6.............................. .4-.6

                                           (162-167)                            (10-15)

1) Release parking brake lever. Loosen cable attaching bolt and adjusting nut, and move cable lever to right. Adjust clearance of left to .04" (1.0 mm), then tighten attaching bolt. Clearance is measured between extension lever and stopper

2) With left cable adjusted, turn adjusting nut until same clearance obtained on right extension lever. With parking brake properly adjusted, lever stroke should be 4-6 notches (8-12 clicks)      

NOTE - Valve accomplishes three functions: Pressure control of rear service brakes; trouble warning; deactivating rear brake pressure control when front service brakes fail.

Pressure Test - Use two pressure gauges that will measure at least 1,500 psi. Hook one gauge to master cylinder rear side and one rear wheel cylinder. Pressure reading should be as shown in chart. Replace defective as required

                      Brake Hydraulic Pressure Chart

Wheel Cylinder.....................................  460±28.4 psi

Master Cylinder....................................  640 psi

Warning Light Test - Slightly loosen bleeder screw of one wheel cylinder and depress brake pedal. At this time warning light should come on. If light does'nt work, check switch and wire connector.

Combination Valve Reset - Tighten whichever bleeder screw has been opened (ie: drum wheel cylinder), then loosen the opposite system bleeder screw (ie: caliper wheel cylinder). Press brake pedal down until light goes out, close bleeder.

Attach a bleed tube to wheel cylinder bleeder screw and immerse opposite end of tube in a container partially filled with brake fluid. Depress and release pedal several times, hold in applied position, loosen bleeder screw, allow air to escape, and tighten bleeder screw. Continue operation until air bubbles are no longer seen in discharged fluid. Repeat procedure at remaining brake lines until all air is bled from system. Bleeding sequence is right-rear, left-rear, left-front, and right-front.

Removal - Raise and support  vehicle and remove front wheel. Remove pad protector by prying up edge of clip of center of protector. Hold center of "M" clip, detach "M" clip from pad and its ends from retaining pins, remove clip. Remove retaining pins from caliper and remove "K" spring. Remove pads from caliper by grasping backing plate are of pads with pliers.

Installation - Press piston to bottom of bore using a suitable tool, install disc pads and retaining pins. Install "K" spring and "M" clip, making sure positions are not reversed. See illustration. Install pad protector, making sure clips face outward.

Removal - With disc pads removed, disconnect hydraulic line and bolts attaching caliper assembly to steering knuckle, and remove caliper assembly.

Installation - Reverse removal procedure, tighten caliper mounting bolts evenly, and bleed hydraulic system.

Removal - With caliper assembly removed, remove hub dust cap, cotter pin, lock nut, and adjustment nut. Pull hub and rotor assembly from spindle, taking care not to drop outer wheel bearing. Remove bolts attaching rotor to hub, then separate.

Installation - Reverse removal procedure, tighten rotor-to-hub bolts evenly, and adjust wheel bearings. See Wheel Bearing Adjustment in WHEEL ALIGNMENT Section.

Removal - Raise and support vehicle and remove brake drum. Remove shoe hold-down springs. Disconnect  strut-to-shoe spring and upper shoe return spring end from trailing shoe. Remove trailing shoe and lower return spring. Hold adjusting latch downward, pull adjusting lever toward center of brake, and remove leading shoe assembly. remove upper shoe return spring and strut-to-shoe spring.

Installation - Reverse removal procedure and note the following: Apply brake greas to all shoe contact points of backing plate, adjuster assembly, and wheel cylinder. Adjust amount of engagement of adjusting lever with strut only after pulling lever fully toward center of brake. Note that adjusting lever and latch spring differ between right and left sides.

Removal - With rear drum and brake shoes removed, disconnect hydraulic line from wheel cylinder at rear of backing plate, remove bolts attaching cylinder and remove wheel cylinder.

Installation - Reverse removal procedure, tighten mounting bolts evenly, and bleed hydraulic system.

Removal - Disconnect hydraulic lines from master cylinder, then depress brake pedal slowly several times to discharge brake fluid. On models with power brakes, remove clevis bolt retaining master push rod to brake pedal, then on all models, remove cylinder attaching bolts and lift off master cylinder.

Installation - Reverse removal procedure, check and adjust pedal height and bleed hydraulic system.

NOTE - Before removal or overhaul test check valve. Pull of vacuum hose, place finger over check valve and crank engine; vacuum should be created.

Removal - With master cylinder removed, disconnect vacuum host from power brake unit. Remove pin connecting power unit operating rod to brake pedal, then loosen attaching nuts and remove power unit.

Installation - Reverse removal procedure and note the following: Apply a suitable sealer to power unit mounting surface and vacuum line connections. Adjust pedal height and bleed hydraulic system.

Disassembly - Remove caliper attaching bridge bolts and separate outer and inner halves. Remove retaining ring and dust seal, apply compressed air to fluid inlet, and remove piston. Remove piston seal taking care not to damage caliper bore or seal groove.

Cleaning & Inspection - Clean all metal parts in trichloroethylene, alcohol, or brake fluid; clean piston seal in brake fluid or alcohol; clean dust seal and other rubber parts in alcohol only. Inspect caliper bore and piston for wear, damage or rust; replace parts as necessary.

NOTE - Manufacturer recommends replacing piston seal and dust seal whenever piston has been removed.

Reassembly - Reverse disassembly procedure and not the following: Apply rubber grease to piston seal and brake fluid to piston when reassembling. If torque plate was removed from inner caliper half, clean torque plate was removed from inner caliper half, clean torque plate shaft and shaft bore in caliper, then apply special rubber grease to rubber bushing, wiper seal inner surface, and torque plate shaft before reassembly. Tighten bridge bolts of caliper halves evenly.

Disassembly - Remove dust boot, retaining ring, stop washer, and piston stop bolt, and withdraw primary piston assembly, secondary piston assembly, and secondary return spring from master cylinder. NOTE - Do not disassembly primary piston assembly. Remove check valve caps, tube seats, check valves, and check valve spring.

Inspection - Check master cylinder bore and piston for wear or other damage and replace as necessary. Check clearance between cylinder bore and piston; if clearance exceeds .006", replace parts are necessary. Check all parts of secondary piston assembly; if any parts are found defective, replace complete secondary piston assembly.

Reassembly - Reverse disassembly procedure and note the following: Apply rubber grease to all parts (except boots) before reassembly. When assembled, check that return part is not blocked by piston cup when piston is located at return position.

Disassembly - 1) Hold front shell flange (master cylinder end of power unit) in a vice and remove clevis and lock nut. Scribe alignment mark on front and rear shells for reassembly reference. Holding neck of rear shell on both sides with pipes, remove rear shell by turning it counterclockwise. NOTE - diaphragm spring can be removed at the same time. Remove diaphragm plate assembly from rear shell.

2) Using suitable driver, remove rear shell retainer and lift out bearing and valve body seal. Pull diaphragm from diaphragm plate assembly, then using a screwdriver, remove silencer and filter. Hold valve plunger, with key hole facing down and remove stop key by lightly pushing valve rod while shaking unit, then remove valve rod and plunger assembly. Remove reaction disc. NOTE - Valve rod plunger assembly can not be disassembled. Remove flange from shell, then pull off plate seal assembly.

Cleaning & Inspection - Thoroughly clean and dry each part. NOTE - Cups and plastic parts must be wiped off only. Inspect diaphragm plate for damage and cracks. NOTE - Diaphragm plate is made of plastic and should be handled carefully at all times. Check push rod for damage and straightness. Check font and rear shells for cracks, damage and deformation. Repair or replace any defective part.

Reassembly - 1) Apply a sufficient amount of silicone grease to the following parts (see illustration): Front shell seal and push rod sliding surfaces (A); push rod and seal contact surfaces (B); diaphragm lug-to-rear shell contacting surface (C); outside surface of reaction disc (D); reaction disc inserting part of diaphragm plate (E); rear shell seal and diaphragm plate sliding surfaces (F); interior of piston plate into which plunger assembly is inserted and seal sliding surfaces (G).

2) Install seal and bearing into rear shell, then press in retainer. Gently install valve rod and plunger, then install stop key witch chamfered end toward piston side. NOTE - After installing stop key, pull plunger assembly to ensure plunger is securely locked by stop key. Install reaction disc and diaphragm in diaphragm plate assembly, then install silencer filter and silencer into rear of diaphragm plate and press in retainer.

3) Install diaphragm plate assembly into rear shell, then install valve body guard (rear end first) into end of seal retainer. Install rear shell into front shell, then install push rod and master cylinder piston (see illustration); clearance should be .30" (7.6 mm) or less. If clearance is not to specifications, correct by adjusting push rod length. Install yoke onto threaded end of power unit operating rod.

Rear axles are hypoid design with center line of pinion set below centerline of ring gear. The axle shafts, pinion and differential assemblies can be serviced without removing axle from vehicle. All differential adjustments are performed using shims. No adjustment for axle shaft end play is necessary.

Only one basic axle design is used on these models. To determine axle ratio, divide number of ring gear teeth by number of pinion gear teeth.

1) With rear of vehicle raised and wheels removed, release handbrake and back off brake shoe adjusters. On models with disc wheels, remove brake drum locating screws and tap drums off hubs. Remove axle shaft retaining screw and withdraw shaft from hub assembly. On models with wire wheels, remove nuts securing drum to hub and tap brake drums off hub. Remove retaining screws securing hub extension flanges to hubs. Withdraw hub extensions and axle shafts.

2) Using suitable tool, remove hub nut and lock washer. Withdraw hub complete with bearing and seal. To install, repack hub bearings with grease and press hub into position. If paper washer or "O" ring was damaged on disassembly, they must be replaced. If seal was removed, drift it into position using suitable tool. Drift hub into axle housing using suitable tools and reinstall remainder of components in reverse of disassembly procedure.

1) Mark propeller shaft and pinion flange for proper realignment and disconnect propeller shaft.Unscrew nut in center of flange, using suitable tool to prevent flange from rotating. Remove nut and washer and withdraw flange and pressed end cover from pinion shaft. Extract oil seal from axle housing.

2) Press new seal into axle housing with edge of sealing ring facing inwards. Replace flange and end cover, taking care not to damage edge of oil seal. Tighten pinion flange nut and reconnect propeller shaft, ensuring that index marks are lined up.

Drain rear axle and remove axle shafts. Mark propeller shaft and pinion shaft for correct reassembly and disconnect shaft. Remove nuts securing differential carrier to axle housing and withdraw complete carrier. To install, reverse removal procedure.

1) Check to ensure that differential bearing caps are marked to ensure correct replacement, then remove bearing cap nuts, washers and caps. Remove differential cage. Remove differential bearings from cage, using suitable tools and note that the thrust face of each bearing is marked "THRUST" and that shims are installed between inner ring of each bearing and differential cage. Knock back tabs of locking washers and unscrew bolts securing ring gear to differential cage, remove ring gear.

2) Tap out pin locating differential pinion shaft from ring gear side of cage as tapered pins are used. Drive out differential pinion shaft and remove pinions and thrust washers from cage. Remove pinion nut, flange and pressed end cover. Drive pinion shaft towards rear through carrier. Pinion shaft will come out with inner race and rollers for rear bearing, leaving outer race and complete front bearing in position.

3) Tap out inner race of front bearing and oil seal. Withdraw outer races using suitable tools. Slide off pinion sleeve and shims. Withdraw rear bearing inner race from pinion shaft using suitable tools. Note spacing washer against pinion head. Remove rear bearing outer race using suitable tools.

Clean and inspect all components for worn or damaged parts. The ring and pinion gear must be replaced as a matched set if replacement of either is necessary.

Drive Pinion Depth - 1) Install outer bearing races in carrier using suitable tools. Smooth off pinion head with an oil-stone, taking care not to remove any markings etched on head. Assemble pinion and rear bearing with a washer of known thickness behind pinion head. Position pinion in carrier without bearing spacer and oil seal.

2) Install inner ring of front bearing and pinion flange and tighten nut slowly until a bearing preload of 8-10 INCH lbs. (9-12 kgcm) is obtained. Using tool 18G-191, adjust dial indicator to zero on machined step "A" of setting block (see illustration). Place dial indicator and base of tool on head of pinion and position tool so dial indicator feeler rests on center of differential bearing bore. Note any variation from zero. Now swing indicator to other bearing bore and again note variation from zero. Average the two variation together.

3) Take into consideration any variation in pinion head thickness. This will be shown as an unbracketed figure etched on pinion head and will always be minus. If no unbracketed figure is shown, pinion head is of nominal thickness. Using average dial indicator reading just obtained and the unbracketed figure from pinion head, perform the following calculation: If indicator reading is minus, add indicator reading to pinion head reading and REDUCE known washer thickness by this amount.

EXAMPLE

   Indicator Reading..................................  -.002"

   Pinion Marking.....................................  -.005"

   Variation from Nominal.........................  -.007"

Reduce known washer thickness by this amount.

4) If indicator reading is plus and numerically LESS than pinion marking, REDUCE the known washer thickness by the difference.

EXAMPLE:

   Pinion Marking.....................................  -.005"

   Indicator Reading.................................  +.003"

   Variation From Nominal.......................  -.002"

Reduce known washer thickness by this amount.

5) If indicator reading is plus and numerically GREATER than pinion marking. INCREASE the known washer thickness by the difference.

EXAMPLE:

   Indicator Reading.................................  +.008"

   Pinion Marking.....................................  -.003"

   Variation from Nominal........................  +.005"

Increase known washer thickness by this amount.

6) The only cases where no changes are required to washer thickness are when indicator reading is PLUS and NUMERICALLY EQUAL to unbracketed pinion marking, or indicator reading is zero and there is no unbracketed marking on pinion head. Allowance should now be made as follows for mounting distance marked on pinion head in a rectangular bracket as follows:

7) If marking is a PLUS figure, REDUCE washer thickness by on equal amount. If marking is a MINUS figure, INCREASE washer thickness by on equal amount. A tolerance of .001" (.03 mm) is allowed in thickness of washer finally installed.

Pinion Bearing Preload - Install washer of thickness just calculated under pinion head and assemble pinion with bearings, pinion sleeve, oil seal, flange and nut. Pinion sleeve is of collapsible design and can only be used once. Therefore, the following procedure should be done with care or new sleeve will be required. Slowly tighten flange nut to specifications while holding flange to prevent rotation. During tightening process, occasionally check pinion bearing preload. When nut is tightened to specifications, preload should be to specifications. Installation of pinion is now complete.

Side Bearing Preload - 1) This method of setting position of ring gear assembly depends on marking given on differential gear carrier and case. The dimension to be considered are (see illustration): "A" - The dimension from center line to bearing on right side. Variation in dimension "A" is stamped on carrier adjacent to right side bearing bore. "B" - The dimension from center line to bearing on left side. Variation is stamped on left side bearing bore. "C" - Dimension from bearing on one side of cage to bearing on other side and "D" - Dimension from rear face of ring gear to bearing on opposite side. Variation on "C" & "D" dimension are stamped on machined face of differential cage.

2) It is possible to calculate shim thickness required on left side by use of follwoing formula

                                            A+D-C+.002"

Substituting the actual variations shown, this formula gives shim thickness required to compensate for variation in machining plus the extra .002" (.05 mm) to give necessary bearing preload. In addition, allowance must be made for variations in bearing thickness in the following manner:

3) Rest bearing with inner race over recess and thrust face downwards on surface plate of tool 18G-191. Place dial indicator on surface plate and zero indicator on step "A" of gauge block of tool 18G-191. Swing indicator over until it rests on plain surface of inner bearing race. Hold inner race down against balls and note indicator reading. Indicator will normally indicate a negative reading. This negative variation should be ADDED to the shim pack previously calculated for that side of the differential.

4) To calculate shim thickness for the right side, use the following formula:

                                           B-D+.006"

substituting the actual values for "B" and "D" as described in 1). Again, final allowance must be made for variation in bearing thickness as described in 3) above.

5) When a framed number is marked on back of ring gear, e.g. +2, it must be taken into account before assembling shims and bearings to differential cage. If, for example, the mark +2, then shims of .002" must be transferred from left (ring gear) side to right side. If marking is -2, shims of .002" must be moved from right to left side.

Backlash Adjustment - 1) Assemble bearings (thrust faces outwards) and shims as calculated to differential cage. Bolt ring gear to differential cage. Bolt ring gear to differential cage but do not knock over locking tabs. Mount assembly on two "V" blocks and check runout by means of dial indicator. If runout  exceeds specifications, remove ring gear and check joint faces on cage ring gear for any particles of dirt. If parts are thoroughly cleaned it is unlikely that ring gear will not run true. Tighten bolts and knock over locking washers.

2) Install differential to carrier. Replace bearing caps and tighten nuts. Bolt surface plate of tool 18G-191 to carrier flange and mount a dial indicator in such way that an accurate backlash figure may be obtained. Correct figure for backlash to be used with any particular gear and pinion is etched on rear face of ring gear. A movement of .002" (.05 mm) shim thickness from one side of differential cage to the other will produce a variation  in backlash of about .002" (.06 mm). Use care to ensure absolute cleanliness during the operation as dirt can result in inaccurate readings and poor settings. Carrier may now be installed in rear axle housing.

MGB & MGB/GT (1968-74)

MGC & MGC/GT (1969)

Rear axles are hypoid design with center line of pinion set below centerline of ring gear. The axle shafts can be serviced without removing axle from vehicle. All differential adjustments are performed using shims. No adjustments for axle shaft end play is necessary. A collapsible spacer is used on drive pinion shaft.

Only one basic axle design is used on these models. To determine axle ratio, divide number of ring gear teeth by number of pinion gear teeth.

1) With vehicle raised and supported, rear wheel remove and handbrake released, remove contersunk screws (disc wheels) or nuts (wire wheels) securing brake drum. Top off drum. It may be necessary to loosen brake adjusters if shoes hold drums. Remove cotter pin and unscrew slotted axle shaft nuts and remove hub. Disconnect brake cable and hose.

2) Remove brake backplate, then remove oil seal collar bearing hub cap and oil seal from axle shaft. Remove axle shaft using suitable tool and press bearing from shaft. To install, repack bearing with grease and reverse removal procedure. Use suitable tool to drift axle shaft into position. Lubricate and install new oil seal with lip facing inwards.

1) Raise and support rear of vehicle, remove wheels and brake drums. Drain rear axle. Mark propeller shaft and pinion flange for correct reassembly and disconnect propeller shaft. Using suitable tool, measure and record torque required to rotate pinion. Using tool to prevent pinion rotation, remove flange retaining nut and washer, withdraw pinion flange. Extract and discard oil seal.

2) Grease edge and sealing lip of new oil seal and install seal flush with axle housing. Install pinion flange and washer, and screw on retaining nut gradually until resistance is felt. Rotate pinion to settle bearings and measure torque required to rotate pinion. If reading obtained is less than value obtained during disassembly, tighten nut a VERY small amount, resettle bearings and recheck torque. Repeat this procedure until a reading equal to previous reading, but not less than 4-6 INCH lbs. (4-7 cmkg) is obtained. CAUTION - Preload build up is rapid, tighten nut with care. If a torque reading in excess of 6 INCH lbs. (7 cmkg) is exceeded, axle must be dismantled and a new collapsible spacer installed. Continue reassembly reverse of disassembly procedure.

1) Rear rear of vehicle and mark propeller shaft and flange for correct reassembly. Disconnect propeller shaft. Remove nuts and washers securing each end of rebound straps to anchor pins on axle and remove straps. Disconnect handbrake at operating levers and remove cable clamp from housing. Remove nut securing brake balance lever to pivot on axle housing. Disconnect shock absorber from rear spring clamp plate.

2) Disconnect brake line and release exhaust pipe from exhaust manifold and supporting brackets, lower exhaust pipe assembly. Remove nut and washer from each spring front anchor pin. Support axle housing and remove rear shackle plates, brackets and rubber bushings. Lower axle support until axle and spring assembly rests on wheels. Remove front anchor pins and roll assembly from beneath vehicle to reinstall, reverse removal procedure.

1) Drain and remove axle from vehicle. Remove axle shafts and hubs. Remove differential cover and mark each differential bearing cap before removal to ensure correct replacement. Remove bolts and bearing caps. Before differential assembly can be removed from axle housing, housing must be stretched with a suitable stretching tool (18G-131 C). Do not stretch housing more than is absolutely necessary or housing may be damaged. Maximum stretch is .012" (.3 mm) or 9 flats of tool 18G-131 C. Pry differential assembly out of housing using care not to damage case or apply leverage on stretcher. Release housing stretcher

2) Bend back locking tabs and remove ring gear bolts and ring gear. Drive out pinion shaft pin and rmeove shaft. Turn differential gears by hand until pinions are opposite operating in differential cage and remove pinions and thrust washers. Remove differential gears and thrust washers, if necessary remove differential inner bearing races using suitable tools.

3) Before removing pinion measure preload; if this is zero, install new pinion bearings. Hold pinion flange and remove pinion nut and washer. Remove flange by tapping with soft hammer. Remove pinion by pressing out, do not drive out. Using suitable tools, remove front and rear bearing outer  races form axle housing. As front race is removed, oil seal will come out with it. Remove rear bearing inner race from pinion.

Drive Pinion Depth - 1) Install bearing outer races in axle housing using suitable tools. Using a dummy pinion (18G-191H), install inner race of bearing on dummy and plate in housing without collapsible spacer or oil seal. Install inner race of front bearing. NOTE - A standard pinion head spacer of .208" (5.3 mm) is incorporated in dummy pinion. Install pinion flange and tighten nut gradually until a bearing preload figure of 10-20 INCH lbs. (11-20 cmkg) is obtained.

2) Clean dummy pinion head and position dial indicator foot on pinion head and zero indicator. Move indicator until foot of gauge rests on center of differential bearing bore and route indicator reading. Repeat this procedure on opposite bearing bore and average the two figures. The reading shown on indicator will be amount of correction necessary from standard spacer of .208" (5.3 mm). If indicator reading is negative, reduce spacer thickness by this amount and visa versa.

3) Allowance must also be made for pinion depth marked on pinion head in a rectangular bracket. If marking is positive, reduce washer thickness by equal amount and visa versa. A tolerance of .001" (.03 mm) is allowed in thickness of washer finally installed. Remove dummy pinion.

Pinion Bearing Preload - 1) Install washer of thickness calculated above under pinion head. Install pinion inner bearing race. Insert pinion into case and install collapsible spacer with small diameter towards shoulder of pinion head. Support head of pinion and press outer bearing onto pinion using care not to compress spacer .Grease edge and sealing lip of seal and install seal flush with axle housing. Install flange, washer and nut.

2) Tighten flange nut slowly until spacer starts to collapse. Rotate pinion to settle bearings and check pinion preload. Continue tightening very small amounts between each preload check until specified preload is obtained. CAUTION - Bearing preload is rapid. If preload torque of 24 INCH lbs. (30 cmkg) is exceeded, pinion must be dismantled and a new collapsible spacer is installed.

Side Bearing Preload - 1) Assemble each inner and outer bearing race to differential assembly. Using ring gear setting tools (18G-191, 18G-191 F & 18G-191 J) place differential assembly onto jig and load ring gear assembly (see illustration). Spin unit to settle bearings. Standard measurement of bearing bores is 7.243" (183.98 mm). Any excess machined from bores will be marked A and B on axle casing. The A and B tolerances added to standard measurement will determine overall dimension, see example

EXAMPLE

  Differential case standard....................... 7.243 (183.98 mm)

  PLUS value "A" stamped on case.......... .001" (.025 mm)

  PLUS value "B" stamped on case.......... .002" (.038 mm)

  Total distance between bores................ 7.246" (184.05 mm)

2) Clean head of jig pillar and place dial indicator on pillar and zero indicator on pillar head. NOTE - Pillar is standard height of differential to settle bearings and move arm of dial indicator to machined face of jig and take a reading. Add this variation to the standard height to obtain total width of differential assembly. For example:

EXAMPLE:

  Differential assembly standard....................  6.972" (177.10 mm)

  PLUS indicator reading.............................    .008" (.203 mm)

  Total differential assembly..........................  6.980" (177.30 mm)

3) Subtract total width of differential assembly, found in 2) above, from total distance between the bores, found in 1) above. To this value, add specified bearing preload value and divide the result by 2 to obtain shim thickness equal values for both sides of assembly

EXAMPLE 

  Total distance between bores...................... 7.246" (184.05 mm)

  MINUS total differential assembly............... 6.980" (177.30 mm)

  Result......................................................... .266" (6.75 mm)

  PLUS bearing preload................................ .004" (.102 mm)

  Total shim thickness.................................... .270: (6.86 mm)

  Shim each side............................................ .135" (3.43 mm)

Backlash Adjustment - 1) Correct figure for backlash to be used with any particular ring and pinion is etched on rear face of ring gear. Increase shim thickness on opposite side to ring gear by this amount and decrease shim thickness on ring gear side by same amount.

EXAMPLE

  Calculated shim thickness............................  .135" (3.43 mm)

  MINUS backlash value...............................  .008" (.203 mm)

  Ring gear side shims....................................  .127" (3.23 mm)

  Calculated shim thickness............................  .135" (3.43 mm)

  PLUS backlash value..................................  .143" (3.62 mm)

2) Install differential in axle housing. Replace bearing caps and tighten bolts. Set up dial indicator to accurately measure backlash of ring gear. If backlash is not at value etched on ring gear, move shims from side to side to obtain correct value. A movement of .002" (.051 mm). shim thickness from one side of differential to the other will produce a variation in backlash of about .002" (.051 mm). Ensure absolute cleanliness during above operation to ensure accuracy. Continue installation in reverse of the removal procedure.

Wipe lubricant from internal parts, then rotate gears and inspect for wear or damage. Mount a dial indicator to housing and check backlash of several points around ring gear. Backlash must be within specifications at all points. If no defects are found, check gear tooth pattern.

NOTE - Drive pattern should be well centered on ring gear teeth. Coast pattern should be centered but may be slightly forward tow of ring gear teeth.

Point ring gear teeth with suitable marking compound, then wrap a cloth or rope around drive pinion flange to act as a brake. Rotate ring gear until a clear tooth pattern is obtained. Gear tooth contact pattern will disclose whether correct pinion bearing mounting shim has been installed and drive gear backlash set properly. Backlash between drive gear and pinion must be maintained within specified limits until correct tooth pattern is obtained.

NOTE - Change in tooth pattern is directly related to change in shim and backlash.

1) With no damage in backlash, moving pinion further from ring gear moves drive pattern toward heel and top of tooth and moves coast pattern toward toe and top of tooth.

2) With no change in backlash, moving pinion closer to ring gear moves drive pattern toward toe and bottom  of tooth.

3) With no change in pinion shim thickness, an increase in backlash moves ring gear further from pinion. Drive pattern moves toward heel and top of tooth, and coast pattern moves toward heel and top of tooth.

4) With no change in pinion shim thickness, a decrease in backlash moves ring gear closer to pinion gear. Drive pattern moves toward toe and bottom of tooth, and coast pattern moves toward toe and bottom of tooth.

Axle housing is banjo type with removable differential carrier and semi-floating axle shafts. Ring and pinion gears are hypoid type in which centerline of pinion is set below centerline of ring gear. Differential case is a one piece, two-pinion design. The axle shafts are retained in housing by cone type roller bearings and bearing retainers at axle housing outer ends.

All LUV models are equipped with one type of rear axle assembly. To determine axle ratio, divide the number of ring gear teeth by the number of drive pinion gear teeth.

Fig. 1 Exploded View of LUV Rear Axle Assembly

Fig. 2 Exploded View of Axle Shaft Assembly

Removal - Raise vehicle and remove wheel and tire assembly. Remove brake drum, brake shoes, and disconnect parking brake inner cable. Disconnect brake line from wheel cylinder and cover end to prevent loss of fluid and entry of dirt. From inboard side of brake backing plate, remove four nuts from the bearing holder through bolts. Pull axle shaft from housing.

Bearing Replacement - 1) Flatten locking tab of lock washer, then mount axle shaft in a vise, clamping vise jaws around lock nut. Using suitable tool (J-24246) positioned on lub bolts, turn axle shaft loose from lock nut, Mount axle assembly in a press and remove lock nut, lock washer, bearing and holder, and brake backing plate. Remove oil seal from outboard side of bearing holder, then drive off bearing outer race with a drift.

2) To reassemble, install bearing outer race and grease seal into bearing holder using suitable drivers. Apply wheel bearing grease to bearing holder, rear axle tube, and bearing inner race. Insert the four through bolts into backing plate, then install bearing holder to backing plate, making sure oil seal plate assembly over axle shaft, position bearing over axle shaft and press into bearing holder. Install new lock washer with dished side away from bearing, and thread lock nut onto shaft. Place lock nut between vise jaws, and using tool used during disassembly, tighten lock nut securely. Bend over portion of lock washer opposite to locating tab to prevent lock nut from turning.

Fig. 3 Sectional View of Axle Shaft Bearing Assembly Measurement for Axle Shaft Shim Requirements

Installation - 1) If both axle shafts were removed, insert a .079 (2 mm) shim between bearing holder and axle tube flange of first axle shaft to be installed. Insert shaft into axle tube and install and tighten bearing holder-to-flange bolts. For the second axle shaft (or if only one shaft was removed), insert shaft without shims into axle tube until it comes int contact with thrust block in differential. Measure clearance between bearing holder and axle tube flange (see illustration).

2) Proper size shim for this location may be determined by adding .004" (.1mm) to measurement just obtained. Select a shim or combination of shims, withdraw axle shaft, and install shims between bearing holder and flange face. Reinstall axle shaft and tighten four through bolts. Connect brake line to wheel cylinder, then install brake shoes, parking brake cable, and brake drum. Install wheel and tire assembly, adjust brakes and bleed system.

Removal and Installation - Raise rear of vehicle, remove wheels and brake drums, and disconnect brake lines of rear wheel cylinders. Disconnect parking brake cable brackets at rear spring location, remove four through bolts from each and flange, and partially withdraw axle shafts from axle tubes. Disconnect propeller shaft from pinion flange and place out of way. Remove nuts attaching carrier to axle housing and remove carrier assembly. To install, reverse removal procedure, making sure to refill axle with lubricant.

Fig. 4 Removing Pinion Shaft Lock Pin

1) Mark side bearing caps for reassembly reference, remove nuts and bearing caps, then remove differential case assembly. NOTE - Keep right and left side bearing races with respective bearings. Remove differential side bearings from case using a suitable puller and adapter (J-22888) and J-81072).

Record thickness of each side bearing and each shim pack then place with appropriate bearing race

2) Remove ring gear bolts and separate ring gear from case. Drive out pinion shaft lock pin using a long drift. NOTE - It may be necessary to remove caulking in lock pin using a 5 mm drill. Remove pinion shaft using a drift, then withdraw thrust block, pinion gears, and thrust washers. 

3) Remove pinion nut and pinion flange. Drive the pinion gear from carrier using a soft hammer or drift. Withdraw front pinion bearing and oil seal. Using a drift, remove pinion bearing races from carrier. Mount pinion gear in a press and remove rear pinion bearing and depth shim from pinion gear.

Fig. 5 Tool Arrangement for Measuring Drive Pinion Installed Height

Drive Pinion Depth - 1) Install front and rear pinion bearing races into carrier bores, lubricate pinion bearings, and position in repective races. Install a suitable gauging plate (J-23597-7) and preload stud and pilot (J-23597-9) through pinion bearings and tighten nut snugly. Rotate bearings and insure proper seating, then tighten lock nut until 20 In. Lbs. (25 cmkg) of torque are required to rotate new bearings, or 8-10 In. Lbs. (9.2-11.5 cmkg) are required to rotate used bearings.

2) Place mounting discs (J-23597-8) onto arbor tool (J-23597-1) and place assembly in position in side bearing bores. Install bearing caps. Mount a dial indicator on arbor post, preload dial 1/2 revolution, then tighten indicator in this position. Position indicator plunger on gauge plate, slowly swing across until highest reading is obtained, then "zero" indicator on highest reading of gauge plate. Swing plunger off gauge plate and note indicator reading. Reading is the correct thickness of rear opinion bearing depth shim for a nominal drive pinion. NOTE - Shims are available in sizes from .086" to .101". An indicator reading of .000" or .001" requires shims of .100" and .101" respectively.

Fig. 6 Location of Pinion Depth Code on Head of Drive Pinion

3) Examine head of drive pinion; pinion depth code is stamped by chemical ink and is the lower of three numbers. A "+" (plus) number indicates need for greater mounting distance (decrease shim thickness), while a "-" (minus) number indicates need for smaller mounting distance (increased shim thickness). See following chart to determine proper shim variation to compensate for plus or minus markings. NOTE - If no pinion depth code is present, pinion is "nominal" and no correction to dial indicator reading is required.

+10.............................................  Subtract .003" (.13 mm)

+8...............................................  Subtract .004" (.10 mm)

+6...............................................  Subtract .003" (.08 mm)

+4...............................................  Subtract .002" (.05 mm)

+2...............................................  Subtract .001" (.03 mm)

0.................................................  No Correction Required

-2................................................  Add .001" (.03 mm)

-4................................................  Add .002" (.05 mm)

-6................................................  Add .003" (.08 mm)

-8................................................  Add .004" (.10 mm)

-10..............................................  Add .005"  (.13 mm)

Fig. 7 Using Pull Scale to Measure Drive Pinion Bearing Preload

4) Place selected shim on drive pinion and press rear bearing on pinion. NOTE - Do not press on roller cage; press only on bearing inner race. Remove gauging tools from carrier.

Pinion Bearing Preload (W/ Collapsible Bearing Spacer) - 1) Place drive pinion and collapsible spacer into carrier, then install front pinion bearing and oil seal. Mount pinion flange on drive pinion, apply lubricant to pinion threads, install pinion nut and tighten to 85 ft. lbs. (11.3 mkg). Rotate pinion to insure bearings are seated, then wind a small amount of string (approximately 4-6 windings) around pinion flange. Using a pull scale, note reading required to rotate flange.

2) Continue tightening nut in small increments until pull required to rotate flange is 17 lbs. (7.7 kg) for new bearings or 7-9 lbs. (3.2-4.1 kg) for reused bearings. CAUTION - Preload builds quickly. Nut should be tightened only in small increments and pull scale used after each small amount of tightening. If preload is exceeded, a new collapsible bearing spacer must be installed.

Fig. 8 Ring Gear Bolt Tightening Sequence

Case Assembly - Install side gears and thrust washers in case. Position thrust washers 180 degrees apart, then roll gears into position making sure they are in alignment to allow installation of pinion shaft. Place thrust block between pinion gears and drive pinion shaft into position, making sure roll pin hole aligns with hole in case. Measure backlash between side gears and pinion gears; if greater than .003" (.06 mm), install selective thrust washers to bring backlash within specifications. Washers are available in thicknesses of .037" (.94 mm), .041" (1.04 mm), and .045" (1.14 mm). NOTE - Increasing washer thickness decreases backlash; decreasing washer thickness increase backlash. Install lock pin into pinion shaft and caulk end to prevent loosening. Install ring gear into position on case, apply Loctite to bolt threads, and install and tighten ring gear to case bolts in a diagonal sequence.

Fig. 9 Checking Ring Gear Backface Runout

Backlash & Side Bearing Preload - 1) If original side bearings, differential case, ring and pinion, and differential carrier are being reused, the original shims may be reinstalled in their respective positions. If only new side bearings are bearing installed, measure new bearings with a micrometer and compare thickness with original bearings. If new bearing is thicker, SUBTRACT difference from shim pack. If new bearing is thinner, ADD difference to shim pack.
2) If new bearings, and/or differential case, ring and pinion, or differential carrier are being installed, new shims must be selected as follows: Install side bearings onto differential case, but do not install shims at this time. Mount case into carrier bores. Move ring gear tightly against carrier on ring gear side (away from pinion), and hold in this position. Using a feeler gauge, measure clearance between bearing and differential carrier on side opposite ring gear. Record clearance.

3) Proper preload is established using the predetermined dimension of .002". Therefore, ADD this dimension to clearance obtained in step 2) for proper preload. This will give required total thickness of both shim packs. Equally divide the total dimension required shim pack thickness for each side.

Fig. 10 Checking Ring Gear-to-Drive Pinion Gear Backlash

4) Remove case from carrier, remove side bearings and install shim packs, then reinstall bearings. Install differential case into carrier, tapping carefully into place. Install side bearing caps in original positions, install and tighten attaching bolts. Measure run-out of ring gear (see illustration). If run-out exceeds .002" (.05 mm), correct by clearing or replacement of parts.
5) Mount a dial indicator against ring gear teeth and measure backlash in three locations. Backlash should be .005-.007 (.13-.18 mm); if not, shims behind side bearings must be adjusted. NOTE - To maintain preload when backlash is adjusted, the total thickness of both shim packs must not be altered. Therefore, if it is necessary to increase one shim pack, the opposite shim pack must be decreased. To decrease backlash, right side shim must be decreased, and left side increased. NOTE - Backlash changes approximately .002" (.05 mm) for each .003" (.08 mm) shim change. After adjustment, make a gear tooth pattern check to insure correct assembly.