XK150 rear axle rebuild
- Rebuild detail

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It is difficult to find a workshop that will take on the task of removing, rebuilding and refitting an XK rear axle. The main issue is that the car will occupy workshop space for a considerable time, and since the car is 60-odd years old, the workshop might not take on the job because of the uncertainties involved.

My solution was to remove and refit the axle myself, with some extra help when two pairs of hands and more muscle was needed. Once removed, I handed over the axle to Hornsby Diffs in Sydney, and left it to the expertise of Adam Berghofer there.

Apart from having no experience myself with rebuilding a rear axle, I had another reason for using an expert workshop to rebuild the axle. My car's previous owner undertook full restoration 1996-99, with all work contracted out. The odometer was reading ~1000* miles when that work started. During the restoration, a new crown wheel and pinion from a reputable UK Jaguar classic parts supplier was fitted with various other parts to the rear axle. Then, 12+ years later and just ~4000 miles, in 2012, the rear axle was again rebuilt for the fifth owner by a general garage-workshop in country NSW, with the odometer at 5176 miles. Based on several observations, including the excessive half-shaft end play and the diff whine, it was clear to me that the 2012 rebuild was not done by an expert. This time, in 2018, it would be.

Adam Berghofer was prepared to rebuild the axle only if I delivered the complete axle to him. Presumably for the reasons stated above, he would not take on the removal, rebuild and refitting of the axle in his workshop. 

The rebuilding of the axle was completed promptly, and a full debrief was provided to me by Adam when I picked up the axle. It was pre-filled with oil, ready for refitting. When the refit was completed, there was no whine from the diff!

Parts replaced:

All bearings
All seals
Crown wheel attachment bolts
Pinion nut
Extra half axle shims were made as required

The ten crown wheel attachments bolts used were Dana part 41221. This special high tensile grade 8 bolt 3/8" UNF x 3/4" has an enlarged hex head (use 11/16" AF socket) and 30 gripper ridges under the head. No lock tabs were used; instead thread lock to complement the 30 under-head ridges.

Special crown wheel attachment bolt sleeves:

Ten sleeves were made by Adam Berghofer to eliminate the annular slack in the ten 7/16" clearance carrier holes.

The steel sleeve dimensions were:
ID:        0.378"     (  9.60 mm)
OD:       0.428"     (10.87 mm
Length:  0.394"     (10.0 mm)


26 spline pinion flange:

The 26-spline pinion companion flange Dana 2-1-1181X was another ebay purchase. Delivered cost from USA: AUD 240.
Tailshaft shortening:

Measurements of the distance between the T5 gearbox output shaft and the new pinion flange face showed that I could not be certain that the original T5 tailshaft would not bottom out in the T5. Also, careful scaling of the original 1950s Jaguar XK150 coachbuiler's drawing did not provide any confidence that I could avoid shortening the tailshaft.

Taking the conservative path, I had the tailshaft shortened by 14mm, and rebalanced. Cost (Hardy Spicer Moorebank): AUD 332.

Why 14mm? That distance is the extra length of the 26 spline flange vs the standard Jaguar 10 spline flange.

Shear load:
3/8" vs 7/16" crown wheel attachment bolts:

The ten CW attachment bolts had to be 3/8” UNF to suit the Dana 44 CW. The Jaguar standard for the XKs, Mk VII+ and E Type was 7/16” UNF. A shear stress check of the suitability of the 3/8” bolts was made – the smaller 3/8” bolts are satisfactory. Also decades of 3/8” UNF bolt use in Jeeps is a further comfort factor.

The shear stress across the unthreaded 3/8” diameter of the four 3/8” UNF tailshaft flange bolts is similar to the shear stress applied to the ten 3/8” CW attachment bolts across the thread minor diameter, after allowing for the torque multiplying effect of the 4.09 diff ratio.

* Odometer history: The fourth owner reset the odometer to zero during a minor restoration in 1976. That owner told the fifth owner in 1995 that the odo was reading ~90,000 miles when it was reset to zero.
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