Rear Axle & Hubs

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The rear axle is a full-floating design, with hypoid gear and pinion in a fabricated axle housing. The axle tubes are pressed in and located with dowels.

  1. Flange - Universal Joint Coupling
  2. Oil seal - Pinion Housing Cover
  3. Outer bearing - Hypoid Pinion
  4. Hypoid Pinion
  5. Inner bearing - Hypoid Pinion
  6. Side bearings - Differential
  7. Axle Shaft
  8. Hypoid Gear
  1. Oil Level and Filler Plug
  2. Side gears - Differential
  3. Pinion - Differential
  4. Spider - Differential Pinion
  5. Thrust Pad - Hypoid Gear
  6. Brake Drum
  7. Brake Shoe (Trailing)
  8. Hub Bolt
  1. Oil Seal - Hub Bearing
  2. Roller Bearings - Rear Hub
  3. Sling Plate
  4. Flange - Axle Shaft
  5. Locknut - Hub Bearing
  6. Lockwasher - Hub Bearing
  7. Adjusting Nut - Hub Bearing
  8. Brake Shoe (Leading)

Specifications

Axle Ratio 6.8:1 (5/34)
Backlash - Hypoid Gear and Pinion Teeth .007 to .011 in. (.18 to .28mm)
Thrust Washer - Diff Side Gear - Thickness .061 to .064 in. (1.55 to 1.62 mm)
Thrust Washer - Diff Pinion - Thickness .060 to .062 in. (1.52 to 1.57mm)
Spider - Diff Pinion - Clearance in Pinion .005 to .007 in. (.13 to .18 mm)
Hypoid Pinion - Inner Bearing Dimensions 25 x 62 x 24 mm
Hypoid Pinion - Outer Bearing Dimensions 50 x 115 x 65mm
Rear Hub - Outer Bearing 60 x 110 x 30mm
Rear Hub - Inner Bearing 75 x 130 x 33.5mm
Diff Case Side Bearing
Chassis R1001-R6078 63.5 x 110 x 22 mm
Chassis R6079 onwards 63.5mm x 110 x 29.37mm

Note: Four Pinion Differential

At Chassis No. R22087, the front and rear axles were modified, to incorporate a 4 pinion differential. The side-gears have their tooth count reduced from 21 to 20, and simultaneously have a changed internal spline from 16 deep splines to 42 shallow splines. (This obviously requires correspondingly changed half-shafts with the matching shallow splines.)

At the same time, the pinion thrust washers are modified; changing from .060-.062 inch to .058-.062 inch.

And if this wasn't enough, the outer pinion bearing is modified to make it more robust; with wider flanges on the inner races of the bearings, the new bearing having an overall width of 2-11/16 inch, and requiring the universal joint coupler to be shorter by 1/8 inch. And, of course this requires changes to the bearing housing & pinion housing cover, each being increased in depth by 1/16 inch.

Note: Replacement Hub Seals

The original leather hub seals can be replaced with a modern lip seal, check your local bearing and seal supplies for a: 3.68 x 5.12 x 0.5in. NBR double-lip rotary shaft seal.

Materials

ComponentMaterial Classification
Axle housing differential carrier Malleable iron casting
Axle housing tubes Weldless steel tubing
Axle shafts 30 carbon chrome steel
Differential case and cover Lepaz No.35 malleable iron casting
Differential pinion thrust washers Phosphor bronze, hard-rolled
Differential side-bearing adjusting nuts & lock plates Mild steel pressings
Differential side bearing caps Malleable iron castings
Differential side-gears, pinions Nickel-molybdenum steel stampings, case-hardened
Differential pinion spider Nickel-molybdenum steel stamping. journals copper-plated after grinding
Differential side-gear thrust washers Hard-rolled brass
Hypoid gear and pinion Nickel-molybdenum steel stamping, case-hardened
Hypoid gear thrust pad Phosphor Bronze
Hypoid gear thrust pad screw Mild Steel
Pinion housing cover Malleable iron casting
Pinion outer bearing spacer Chrome steel, case-hardened
Universal joint flange 35 carbon steel
Rear cover gasket, oil filler plug gasket Composition cork
Axle shaft flange attaching studs Manganese-molybdenum steel
Brake drums Chrome cast iron, high duty
Hubs Malleable cast iron
Hub bearing adjusting nuts Mild steel stamping, case hardened
Hub bearing locknuts 40 carbon steel stamping
Hub bolts 35 carbon steel
Oil deflectors Mild steel pressings
Sling plates Mild steel

Torque Specs

Item Specification
Universal Joint Coupling Bolts 75 to 80 lb. ft. (100 to 108 N m)
Hypoid gear to differential 110 to 120lb. ft. (149 to 162 N m)
Pinion input flange retaining nut 225 lb. ft. (305 N m) to 275lb. ft (372 N m)
Rotational resistance of original pinion bearings 2.5 to 6lb. (11 to 26N)
Rotational resistance of new pinion bearings 4.5 to 13.5 lb (20 to 60N)
Hub bearing adjustment Using spanner part No. Z8079: As tight as possible by hand only, and slacken back 1/6 of a turn.

Axle Shaft

Run-out limits:

Differential, Hypoid Gear, and Pinion

Wear checks and limits
Pinion/spider-journal clearance .005 to .007in. (.13 to .18mm)
Inner pinion bearing outer race in diff carrier Press fit: 0 to .0018in (.033mm) interference.
Inner bearing inner race on pinion spigot Press fit: 0 to .0009in (.023 mm) interference.
Outer bearing race in pinion housing Push fit: .0006in. (.015mm) interference to .0012 in. (.031mm) clearance
Outer bearing inner race on pinion shaft Press fit: .0005 to .0015 in. (.013 to .038mm) interference
Side bearing inner race on diff case spigot
(Chassis R1001 to R6078)
Press fit: .0015 to .0035 (.038 to .089mm) interference
Side bearing inner race on diff case spigot
(Chassis R6079 to 9760)
Press fit: .002 to .0035 in. (.051 to .089mm) interference
Side bearing inner race on diff case spigot
(From Chassis R9761)
Press fit: .003 to .0045 in. (.076 to .114mm)
Hypoid gear mating face run out .003 inch (.076mm) max
Hypoid gear rear face run-out .005 inch (.13mm) max

Rear Hub and Brake Drum Assembly

Hub Bearing Inner Race Clearances
Outer bearing on Axle Tube .0006 to .0022 in. (.015 to .056mm)
Inner bearing on Axle Tube .0002 to .0018 in. (.005 to .046mm)
Hub Bearing Outer Race Interference Fit
Outer bearing in Hub .0019 to .0037 in. (.048 to .094mm)
Inner bearing in Hub .0021 to .0041 in. (.053 to .104mm)