So then I chucked it up in the mill to bore the taper. This was intimidating, as there is nothing perpendicular or true about the steering arm, so I expected a major battle. I was happily disappointed!
Just for laughs, I chucked it up in the vice on some parallel bars, with plenty of room below for the taper to pass through. This was clamping on the round sides of the steering arm end, which are rough cast and have an irregular profile any way you look at it. Plus, it was supporting the entire weight of the spindle. I really expected it to launch the spindle at my belly the instant the reamer started cutting. I was tempted to machine a flat on each side to clamp on, but it seemed fairly solid even with this marginal clamp.
I decided to gingerly start boring at 250 RPM and see what happened, prepared for the worst. Much to my surprise, it just pushed right through the cast iron like warm butter. I've been doing so much work with steel since I put my machine shop together, I'd forgotten just how easy cast iron works.
My goal was to bore slightly deeper than the original taper, so that the tie rod would contact about 2/3 of the parent material from above. Whatever was left of the taper would fill in the remainder, but likely not be critical.
Well, just over half way through, the insert came out. I decided I didn't care and pressed on to 2/3, as indicated by a Sharpie mark on the reamer.
I'm very pleased with the result. The first picture shows that the tie rod did not fully seat in the stock hole and does fully seat in the new hole. It doesn't show in the photos, but the small end of the taper does not reach the bottom of the hole in the stock config. Actually, you can infer that: since you only see threads emerging in the "after" photo, so you know there's at least as much thread inside the outer taper as there is inner taper showing above the casting...about 1/8". (Does that sentence make your head hurt too?)
So the bottom line is, I feel there is as much or more mating surface in this configuration than the stock config. Even if my clever insert had worked, I don't think it would have amounted to much. After doing all this, I do not recommend filling the taper with an insert or welding. Just ream it, put a hard washer under the nut, and run with it...especially for a car 1/2 the weight of the donor.
I also don't think you'd need a mill to do a good job. The alignment is not critical, so I think you could even get away with a slow hand drill. In fact, if you don't have a good vice on your drill press, it might be easier to just leave the spindle mounted on the car and use a hand drill than to try to jig it up in the drill press. Keep your RPM's low. There is no reason for anyone to be intimidated about doing this...it really is a piece of cake.
Well, that's it for tonight. I spent a couple of hours to do the first spindle. The second one will take all of 10 minutes...if I don't hurry! Next I'll dial in exactly where the rack needs to go with the new tie rod location. (Yeah, yeah...I know I should have analyzed that first, but it will be SOO much better than before, I haven't got much to lose, and the eyeball says this will be close to on-target anyway.)
File comment: The stock location. Notice that almost 1/8" of the large end of the taper is not seated.
tierod.below.jpg [ 41.57 KiB | Viewed 1813 times ]
File comment: The new location. Note the large end of the taper is fully seated.
tierod.above.jpg [ 41.57 KiB | Viewed 1813 times ]
File comment: What was left of the insert
tierod.insert.ejected.jpg [ 26.95 KiB | Viewed 1814 times ]
...nowadays people are so intellectually lazy and lethargic that they can't build ANYTHING with their hands. They'll spend hours watching whiny people marooned on an island, but won't spend a second adding anything to the world. -weconway
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