Spiral bevel drive, semi-floating shafts manufactured by E.N.V. Axles Ltd - capacity 3 pints.
Early rear axles had six spline halfshafts with an integral oil filler hole cast into the differential nosepiece and closed by a hexagon headed brass plug. The later rear axle had ten spline halfshafts with a bolt-on brass filler hole.
Track measurement is 4'0", semi-floating, spiral bevel driven type rear axle is fitted with two differential pinions and has a ratio of 5:1 (40 crownwheel teeth : 8 pinion teeth).
Differential carrier bearings (Briggs) were SKF part #30207.
Differential pinion (outer) bearing (Briggs) was Skefco part #L132278.
Differential pinion (inner) bearing (Briggs) was SKF part #CRM 8.
Drain and refill every 6,000 miles with (eg.) Caltex Thuban E.P.140.
The 6 spline axle may suffer from pinion failure and (rarely) from halfshaft failure, whereas the 10 spline axle may suffer from halfshaft failure.
The rear axle is a weak point of the car. Do check the oil level periodically as this can lead to bearing failure and bearing failure will lead to gear teeth failure.
Worn bearings cause whine, knocking and loose engagement of the gear teeth. Loose engagement causes pinion failure.
Crownwheel mounting bolt fatigue may initially cause knocking which may go away once the loose end gets bent - overhaul immediately any axle faults are diagnosed since spares are hard to come by.
To remove axle from car disconnect propeller shaft, brake and shock absorber linkage, check straps and spring U-bolts. Remove brake drum, shaft and bearing assembly from one side and pass axle through springs. Axle shafts carried on ball bearings retained against shoulder at outer end of shaft by nut. Outer race of bearing carried in housing which is spigoted and bolted to axle tube flange with brake backplate. Outer end of axle upset to form flange for wheel studs and brake drum. Felt oil seal inside axle tube. Lipped oil seal in bearing housing, behind bearing (lip to bearing).
To extract shaft disconnect brake linkage at centre compensator and remove nuts round axle tube flange. Brake, axle and bearing assembly can then be drawn off. To reassemble insert axle with backplate before fitting brake drum, so that bearing housing bolts can be pushed through flange. Bevel pinion shaft carried in roller inner and double-row ball outer bearings retained in housing by ring nut. Distance-piece between inner races of bearings. No adjustment for bearings. Packing piece and shims behind outer race of outer bearing for bevel mesh adjustment. Crown wheel spigoted on split differential cage and bolted up with cage bolts. Differential assembly carried in taper roller bearings in split housings. Tighten ring nuts and slack back one notch after adjusting mesh to give o.oo8" backlash.
Halfshaft failures are typically due to fatigue failure rather than mechanical overload failure - inspection shows that the halfshaft is far stronger than is necessary to transmit the load, so it could be made thinner and stronger by redesigning the shaft around the failure area to move the stress away from the splines. It may be possible to re-manufacture halfshafts from EN8 steel, reducing the diameter of the halfshaft away from the end of the spline, to allow extra windup, hence reducing the stress at the spline.
It may be possible to adapt the Morris Oxford or Vanden Plas Princess halfshaft to fit the (10 spline) axle. Please let us know any further details if you attempt (or have attempted) this.
For the early Briggs-bodied LD10, the same crownwheel, pinion & differential nosepiece was also fitted to the Lagonda Rapier axle and to the H.R.G. axle.
This rear axle may be a type A165 and the nosepiece is probably an NM129-1.
Note that the H.R.G. crownwheel and pinion ratio is 4.5:1, compared to the 5:1 ratio used on the LD10. The decrease in the overall first gear ratio would be unlikely to affect the LD10 much, but the reduction in engine speed at 70 mph would be a real improvement and would bring the peak power band to a lower speed, which would give more useable acceleration at higher road speeds. At the road speed that gives a normal engine speed of 3,000 rpm, the 4.5:1 differential would reduce the engine speed to 2,700 rpm.
Differential bearing equivalent part numbers :
|Bearing||SKF||Timken||Hoffman||Ransome & Marles||Fafnir||RIV||FAG||BS|
|Pinion (outer, Briggs)||3305||DA 325||MDJ 25 K||6BBNOn||3305X|
|Pinion (inner, Briggs)||CRM 8||RMS 10||MRJ 1||RMS 10||PBPV8||RRM1|
|Pinion (inner, Barker)||32207||32207||01/02/7407|
|Pinion (outer, Barker)||30305||247-243||01/02/7305|
Oil seal equivalent part numbers :
|Rear Hub (Briggs)||1.3/4" 2.1/2" 5/16"|
Steel & Leather
|Rear Axle Halfshaft Oil/Grease Separator (Briggs)||Steel & Felt||2251125 (rubber)|
|Differential Pinion (Briggs)||1.3/8" 2.1/4" 1/2"||NA213||C122|
|Rear Hub (Barker)||1.1/8" 2.1/4" 3/8"||NA430|
|Rear Axle Halfshaft Oil/Grease Separator (Barker)||Steel & Felt||2251125 (rubber)|
|Differential Pinion (Barker)||35mm 69mm 6mm|
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Note, however, that due to slight scaling inaccuracies during both the scanning and inevitably the printing, these images should be taken as an approximation for reference only.
In addition, drawings, measurements and notes of materials used are intended as a guide and aid to the restorer, and not necessarily a definitive, or even guaranteed correct, reference.
Crownwheel nut and bolt for the earlier (six spline) axle.
1. Use S quality bolts with rolled threads. 3/8" U.N.F. (24 T.P.I.)
2. Use Jaguar X.K. bi-hexagon big end nuts (3/8" U.N.F.) instead of plain hexagon nuts in order to facilitate the use of a socket and torque wrench. (It is not possible to fit anything other than an open ended spanner over the standard hexagon nut).
3. Tighten the nut to maximum torque (40 lbs-ft - from the G.K.N. torque table)
4. Drill all the bolts and wire them together so that, if they fail below the heads, they will not come out and crash against the casing.
Penrite recommend Mild EP Gear Oil for use in the LD10 rear axle (document kindly reproduced here with permission).
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