SVreX (Forum Supporter) said:
I've seen lots of lug bolts shear off. I've never seen an axle hub shear off.
I realize the intent of hub centric is for centering, but I sure like my wheels fitting snug to the axle hub in addition to the lug bolts. I think the odds of shearing a lug bolt are significantly reduced when there is no movement against the studs because the center of the wheel is held firmly in place by the axle hub.
But the wheel isn't held "firmly" in place by the hub bore on most wheels. Technically it's not even really touching it (or at least not with any actual holding force) when the wheel is correctly bolted on (exception is when you have corrosion or other crap in there, which often causes a tight fit, or if it's on a mag-style wheel with non-tapered lugs (like many trucks).
If lugs are shearing, it's due to damage (hitting a curb or something), not tightening lug nuts enough (wheel gets loose, breeaks studs), or overtorquing with impact gun. A properly-torqued wheel will virtually never break a stud. I've NEVER broken one for any reason - and that includes a dozen stage rallies and 50+ rallycrosses, several enduro races, and lousy DC streets.
** exception: I've sheared them off on old project cars I bought when removing lug nuts that were seized/rusty/overtorqued by previous owners, but that would not have been changed with hubcentric or non-hubcentric wheels one bit.
In reply to irish44j (Forum Supporter) :
Tangential: There was a thread on RX7club a ways back where someone with an FD was bitching out a repair shop for "overtightening his lug nuts" because all of his studs were spinning in the hubs.
Turns out, he had been torquing the lug nuts fairly loosely.
I had to patiently explain that bolts can be thought of as springs, and by going with a super low torque, the wheel would be able to walk back and forth on the hub with brake and acceleration forces. This will egg out the stud holes in the hubs, making the splines loose.
edit: Found the thread - fifteen years old! https://www.rx7club.com/suspension-wheels-tires-brakes-20/odd-lugnut-problem-will-not-loosen-544452/
He was under the impression that torque on the lug nuts would put a twisting force at the hub. That is not how threads work!
Years ago I sold some e30 wheels to another e30 guy, who showed up at a rallycross and put them on the car (painted blue, you may remember them from when I came to Ohio for GLDivs).
Second run, right rear goes flying off across the Frostburg lot. He said "I didn't want to tighten them too much" and on the first run they had ovaled out the wheel holes, and broke one stud. IDK how he didn't notice it, but I guess rallycross always feels bumpy lol....
Sort of a related question: Have any modern cars come from the factory without hubcentric wheels?
In reply to David S. Wallens :
I don't think so. It wouldn't make sense in the assembly line process as the machine would have to hold the wheel in place and then slowly apply the nuts to center the wheel. Hubcentric makes it like the rotors, easy assembly with less motion
In reply to David S. Wallens :
I can only think of the 240Z. Not sure about later S30 chassis cars.
For a while, Ford trucks had the genius idea of using flat faced lug nuts and a rubber O ring on the pilot to center the wheel. Even when new they were a complete nightmare to R&R the wheels, rust only made it worse. I think they only did this for '97 model year, maaaybe '98. Anyway, that is the reason for the funny groove in the pilot on that generation truck.
