Have found that the studs on my drilled rear hubs have been welded to the hubs.
Is this O.K or do I need to dump these hubs and do the job properly?

Robert

A car I purchased from that famous place in Atlanta had one hub with welded on studs and the other side didn't! I guess maybe they were 1/2 right?? All the studs however were press in type studs, not screw in. If yours are screw in studs that have been welded in, you can start grinding or start all over.

It isn't the correct way to do it, but if they are press in studs and the studs are OK (straight and threads not damaged) and the studs are installed hub centric, then it will work fine unless you strip or break a stud at sometime in the future.

You could take the hubs to a machine shop and have them check the runout of the studs and the hub centricity of the stud installation.

I normally tack weld the backs of the studs on converting a late style hubs. there is not enough metal for the splines to grip.

Geoff

A buddy of mine has a tool for drilling out from 4-5 lug. I thread mine and just turn studs in. Yeah, the late hubs don't have as much metal to thread through, but I haven't run into problems yet. Yet. A little lock-tight keeps the studs in place just fine.

If I had a better welder, I would build up a little metal on the backside before I drilled out the new holes.

Late hubs are tapered on the back and thin. the studs probably spun. I tacked mine for the same reason.

Early 70-71 hubs have the extra bosses cast into them for strong 5 lug hubs.
Geoff

There have been no failures with the exception of poorly installed studs.

What Geoff says... the material on a spot faced 914 hub is now down to 4mm. If the stud is installed improperly or the hole was even slightly too large then the stud will not properly seat making it difficult if not impossible to torque your wheel bolts properly.

A standard 914 boss is 10mm deep. A 914-6/911 hub boss is usually 8mm.

I use a 6mm ring boss to bring my new holes back up to the 914 spec but I think that's overkill. I've never heard of a 914 hub (72-76) that was spot faced to 4mm fail because of the material being too thin. Meaning; I've never seen the material around the stud crack causing the hub failure. I've seen pictures here of one fail "OBVIOUSLY" because the hub was not spot faced and the stud was installed improperly. Much of the bad rap on studs has been because the stud was not properly installed.

Bottom line; with 4mm of boss on the hub, welding can be an attractive option. One would have to be VERY careful (again, because of the amount of material being 4mm) not to warp the hub when welding. I would recommend a tack on the top edge of the stud. The part closest to the bearing surface.