The Following was contributed by Charles Linn of New York, NY, USA via the MG Experience Forum
My wheel stud saga began when an idiot at a tire place broke off a couple of wheel studs when putting new tires on my Bugeye. Without going into too much detail, I got some studs from VB and had him put them in. I figured I should anticipate that more will break off someday, and for good measure had him put all new studs on that wheel too. I collected the used Mowog studs just cause I never throw anything away.
Fast forward a year and I was taking one of the wheels off for the first time since this guy worked on them, and lo and behold one of the new studs is spinning, so I can't get the lugnut off. We had a discussion about this here: wheel stud woes..
I took a Dremel and some abrasive wheels to it and had it off in about an hour. When this one new wheel stud was torqued down, probably with an impact gun despite my EXPLICIT instructions to this moron not to use one, that stud must have spun, and so its splines basically ground out all of the metal that would normally secure the stud's splines to the wheel. How? Well, your wheel studs are much harder than your cast iron hubs. You have an interference fit, and if the stud is too small it could very well just grind the hole in the hub larger.
Because I have heard so many bad things about new parts I decided to do a little investigation. Below are three studs. From left to right, an original MOWOG stud, a stud I sourced from Robert Kirk, and I have no idea where he gets them (will edit this post when he tells us) and a replacement stud sourced from VB. These are 3/8" diameter
Now, from top to bottom, an original MOWOG stud measuring at .406" plus or minus; the stud from Robert measuring out at .403" plus or minus. And, a VB stud measuring out at about .4005". I am measuring the diameter at the fattest portion of the stud, near the head. I did do a sample of four of each kind and these are about average. Obviously these are not manufactured with the same tolerances as main bearings!
Now, Hap said in a previous post that he likes an interference fit of about .002 on these. In other words, the splines at their fattest must be at least .002 bigger than the hole. Hap, correct me if I misunderstand.
So, I will leave it to you to make your own conclusion about whether it is really possible to get a .002 interference fit with the VB stud if you are replacing an original MOWOG stud, which is .0055 larger. Probably the stud from Robert Kirk is going to be okay IF you are careful. NO IMPACT WRENCH.
I know this is not going to rank up there with the front wheel bearing controversy. I just thought people would find it interesting. As Hap points out, you can go to 7/16 studs. I don't think I have the skill or equipment to do the job the way I believe it needs to be done, and since I have extremely limited time to work on my car I decided I don't want to spend it doing that. BTW, I solved the problem by replacing the screwed up hub with a used one, with four original MOWOG studs.
I will update this page as the story develops. . .
©Seth Jones 6/13/2011