It connects to the steering shaft using a set of shoulder bolts, washers, nuts and rubber bushings. Fortunately, I had a new set, provided by Mark, the prior owner. However, the instructions had some dire warnings. In a section with the heading "IS THE FLANGE THREADED OR NOT?" they stated that the flange should be threaded, but they were often drilled out by mechanics after they were old and damaged. As you can see above, mine is in that category. The holes were drilled 5/16", the nominal size of the bolt's thread.
The instructions said that if that was the case, I should have a machine shop weld the holes shut and have them drilled and retapped to the obscure British Standard Fine thread they should have. I called Moss technical support and asked if I really had to do that, and after some research, the answer was, "definitely." If you don't, the steering is held together only by some lock nuts, and that's not enough for a mission-critical, high-vibration part. The right way is for the shoulder bolts to thread into the flange and be tightened to 20 foot-pounds, and then jammed with a second Nyloc nut.
I then asked for opinions on the Volvo Engined MG group that I'm part of, and got a few answers. The consensus seemed to be, "Put the Nyloc nuts on, and check them frequently." However, Charlie, the group leader, admitted that he had actually had one of those shoulder bolts come undone and the bolt was lost. In the online magazine "Totally T-Type 2" I actually read of someone who lost two of the three!
I wanted to do better, but I wasn't too thrilled with the idea of having the flange welded and re-tapped. In the first place, it's an irreplaceable part except by finding another used one. I'm also dubious of the metallurgy of a welded hole, unless it's done by a real expert. I thought of another solution: make some new shoulder bolts with enough thread for two nuts. Here's my design:
Even though I have some hobby-grade machine shop equipment, this critical part felt a little beyond my comfort level. I enlisted the help of my friend and mentor Phil Oles, who has a shop full of gear and plenty of metal. He chose a 3/4" bar of 1144 steel, which is specified for high torque and load bearing applications. I had already specified fine threads, which have greater holding power.
When I arrived at Phil's shop today, he had already started from my print and had three blanks trimmed to size and threaded:
From there, we used the metal cutting band saw to cut the back two to length, and then faced them on the lathe. All that remained was to use a hex collet block to hold the bolt while we turned them into hex nuts:
Here's a family portrait with the flange, the three new bolts and the original bolt. The two standing up tell the story - the new bolt is just like the old one, but slightly longer to allow two nuts.
And, it all worked great! I installed the flange on the new steering rack and assembled the steering shaft to the flange using the new bolts with the bushings from the coupler kit. Charlie will be dismayed that I didn't buy the appropriate BSF threading die, but instead used good old American UNF 5/16-24. I assembled it with grade 8 hardware, torqued to 20 foot-pounds, and then jammed it using grade 8 Nyloc nuts. This ain't coming apart!
Except... despite my best efforts, I managed to install it so that it has about a quarter-turn more range in one direction than the other. That will bug me for the rest of my time with the car if I don't fix it, so tomorrow I'll pull it all back apart and mess with it until it's even. Oh, the perils of perfectionism...
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