More work for the CAD
Just a few days after receiving the spacers I was back on the computer working up another drawing to be turned into metal. The cause this time was a 1957 Series I 88-inch, well-used but full of character, which had been trailered in with a broken rear halfshaft. A local garage had started stripping it down, realised what they were getting themselves into and baled out while the vehicle was still movable. So now it was my turn.
Anyone familiar with Series Is will understand the problem straight away. The rear halfshafts on these vehicles are of semi-floating design. The inner end slides into the differential on coarse splines just like the later vehicles, but at the outer end the wheel bearing is pressed onto the halfshaft, the end of which forms the hub to which the wheel is bolted. The bearing sits in a carrier that is bolted to the end of the axle. The entire assembly (hub, bearing, halfshaft and brake backplate) can easily be removed by undoing a ring of six bolts, but after that it is all bad news.
To change the halfshaft it needs to be pressed out of the bearing and carrier. This requires a very large hydraulic press (they have been known to take 30 tons of pressure before they come apart), and some special mandrels to support the bearing carrier, which were very expensive when new (pretty much a main dealer only tool) and almost impossible to find now at any price.
The nearside halfshaft is unavailable anywhere, the offside is £400. A new wheel bearing is another £60, and that is always assuming the hub carrier (£200) isn’t worn out, and that you don’t wreck it trying to get the halfshaft and bearing out. The design is almost identical to that of the wartime Willys Jeep, sacrificing ease of maintenance for rapid, low-cost manufacture.
Back in the old days, the quickest and cheapest solution (if you couldn’t find a good second hand halfshaft and hub assembly) was to swap the rear axle complete for one from a Series II or III, and a fair few surviving Series Is have these axles fitted. However, good rust-free Series rear axles are not much easier to find these days than Series I halfshafts.
The ends of the axle casing on a Series I are identically dimensioned to the later vehicles, so later hubs and stub axles will bolt on quite happily, but the axle casing is slightly narrower. Only an inch and a bit, but just enough to ensure that post-1958 halfshafts and drive flanges will not fit. Late long wheelbase Series Is had fully floating rear halfshafts of the correct length (or so I am told), but these are around £400 a pair.
The solution I adopted was to have some thick spacers machined up to fit between the drive flanges and hubs, allowing the conversion to be done using cheap Series III parts.
My CAD software only draws in two dimensions, so the drawings I produced needed further work before the instructions could be fed into an automated lathe.
There seems to be a shortage of machining capacity in East Anglia, but after ringing round a few machine shops and speaking to managers with machining jobs stacked up for months, I was pointed in the direction of A&F Engineering in Norwich, who specialise in one-off and short-run work. They did a first-class job, delivered a day earlier than promised and at a very acceptable price.
The spacers were still not cheap as a one-off job, but the total cost to convert both sides, parts and labour, came in around the same as one new Series I halfshaft and bearing.
I will probably see about having a few more sets made up, as I can’t be the only person who will ever come up against this particular problem.