Mike:
I've done this conversion on my 67 vintage race car and am about to do it
again as I convert my 72 from wire wheels to alloys. The stud pattern is
4.0". I used 7/16-20 studs from Pep Boys. They come in two lengths, 1 5/8
and 2 1/8. The length you use depends on the style and size of your
(actually, the car's) nuts. Measure the knurl diameter of the new studs and
drill a slightly smaller hole in the hubs so they press in tightly. Twice I
had studs turn so I welded the heads of the studs to the hubs from the back.
Race car wheels come off and on much more frequently than street car wheels
plus I torque them to 50 lbs.
The front and rear hubs and the drums are relatively easy to drill because
they are soft. The axles are a bitch. Make the holes in the axles and the
drums slightly larger than the holes in the hubs. The holes in the hubs have
to be tight enough to not let the studs turn and to keep them parallel with
each other (unless you weld them). Since the drums and axles have to slide
over the studs, the holes in them need clearance for any small non-parallel
condition of the studs.
When I pressed the studs into the holes, I pulled them tight and straight by
putting the hub on a wheel and torqueing all four wheel nuts to 100 lbs. I
also mounted the hubs to an old wheel when I welded the studs. This way you
know the studs will fit through the holes in the wheels.
Make sure the larger nuts you buy have a bevel compatible with the
bevel on the wheel. I used aftermarket nuts from Pep Boys with shoulders and
washers for my Western alloys on the race car and had no problems. When I
changed wheels to Minators, which have the British bevel, I couldn't find
American nuts in the right thread size with the British bevel to match the
wheels, so I drilled and tapped 16 Rostyle nuts and two extras just in case.
I wrote a long article for the new Midget and Sprite Magazine on
this topic and it is supposed to be in the first issue coming out soon. I' d
be glad to send you a copy of the article if you email me off list.
Lots of luck,
Bob Spruck
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