Last month when I went to take my street wheels off to put on the holies for autocross, I found that the aluminum hubcentric rings for my Konig Rewinds had fused to the hubs. Since I've converted to studs and lug nuts instead of the stock lug bolts, do I even need to use the rings? Seems like the studs will center the wheel automatically.

 

Studs & nuts won't "auto-center" the wheels any more or less effectively than the factory lug bolts.

That being said, for autocross speeds, you'll probably be fine without the centering rings. If you tighten the nuts gradually in a criss-cross pattern, the sloped shoulders on the nuts will keep the wheel centered on the hub as you tighten them (just like the slope-shouldered factory lug bolts).

 

Yes.

 

Not necessarily.........the rings are only there to make positioning the wheel on the hub easier. Once the wheel is torqued on it is centered on the hub.

 

Heard some wheels work better at this then others. Had mine put on and driving home had a bad vibration. My installer never does a bad balance. Then I realized that I'd forgotten to give him my rings. Got home..put them on..the driving was smooth..not a bit of vibration. So In my experience no rings=no good.

 

My experience has been that few wheels are really good at being "stud centric" and centering rings are a real plus. This also is a better load path to the hub than putting the four threads in shear to support the car. And lastly, I believe that alum rings are superior to plastic if you have a choice.

 

With or without centering rings, there shouldn't be any shear stresses on the studs/lug bolts, because they'd fail pretty quickly.

There should only be axial stresses on the studs/bolts, and the slight stretching of the studs/bolts from the axial stress as they're tightened serves to clamp the mating surfaces of the wheel/hub together. It's the frictional force between the two mating surfaces that actually supports the car.

Now, if the lug bolts or nuts loosen up and the mating surfaces are allowed to slide against each other, that *will* introduce huge shear stresses on the studs/bolts. In that case, it would be nice to have either hubcentric rims or centering rings, so that the bolts/studs aren't having to deal with *all* of the shear stresses, but if you're at that point, something has already gone wrong (the wheels are coming loose).

 

+1

Especially if you track your car and/or autocross, where you're really braking hard, and often. Plastic rings can get melty in that kind of heat...

 

Started out with plastic ones and didn't know they were there. Click HERE to see how I found out.

Switched to aluminum and put a thin layer of anti-seize on them to prevent them from fusing to the hub and they fused anyway. Tomorrow I'll just beat and pry the hell out of them to get them off and put on a fresh set. Thanks for the input everyone.

 

So you would call hanging the weight of one corner of the car on the shanks of four studs alone axial stress?? I'm not following your thought here.

I view it as shear simply because you have 1200lbs (MINI, more on other cars) being fully supported by the studs. (Surface tension not withstanding) The entire load path is supported through the cross section of the stud.

Under any hard cornering load on the studs would be quite high and with no support for the wheel, prone to bending. Or ultimately shearing off. With the centering ring in place the load path is largely through the wheels center fitting snugly on the hub.

Not the best idea but I have seen it done and without failure. A lot. In fact when the first SHO kits I produced were made we had to use a .650" thick hat cross section to move the wheel out- think built in spacer- and all the hubs were re fit with longer M12 studs. None ever failed, even under extreme track use, but only the Ford wheels were machined well enough to handle being stud centric. Customers who later ran 17s had issues and needed custom rings to fit the wheels on. *a feather for oe parts for once!

 

I'm just going to talk about lug bolts, so I don't have to keep typing "lug/stud", but this is true for studs as well.

When you tighten a lug bolt, you're actually stretching the bolt. This is purely an axial load (along the long axis of the bolt). The resulting clamping force from the bolt wanting to return to its original length is what holds the mating surfaces of the wheel and hub together. No shear loads so far.

As long as the clamping force between the mating surfaces of the hub and wheel are strong enough to keep those two surfaces from sliding against one another, there will *never* be any shear forces on the bolts (forces acting perpendicular to the long axis of the bolt). It's only if the hub and wheel mating surfaces start sliding against one another that you would have shear forces (and this is a bad thing).

In fact, picture this - if you have four lug bolts, but three are more than adequate to keep the two surfaces clamped tightly together, you could actually replace the fourth bolt with a plastic replica and drive around, and you'd never deform the plastic "bolt".

Bolts are designed to work with axial (stretching) loads. If they get significant shear (perpendicular) loads on them, that's when they start snapping off.

 

ive had a wheel shear off the studs on a car without hubcentric rings before, on the freeway at 45 mph. lugs were torqued to spec and there was no play.

get the hubcentric rings.

 

Do you need hubcentric rings for the stock wheels? I have the stock 16" bridgespokes if that makes a difference.

 

No - the opening in the stock wheel has the same diameter as the hub (56.15 mm, I believe).

 

MINI branded stock wheels do not need rings. When you go aftermarket that's when you need to check to see if you need them. The holies I use for autocross are OEM MINI wheels. My Konig Rewinds are not.

 

Ok, I'm with you Scott. My only concerns would be that we are making the assumption that two 5" diameter plates held with four 12mm studs with a torque stretched rating to 90lbs each is going to exceed the forces necessary to move those two 5" plates upon one another perhaps 1/4" due to the lack of a ring.

I fully confess that I don't know what force will be necessary to do this and I suspect it's based in part on the torque value but also upon the total mating surface in square inches. Certainly a MINI is not likely to generate enough load (although the hubs ARE much less than 5") but doing some calculations on a hard brake pull of perhaps 1g load / 8 bolts would be interesting to look at. Then consider a car that weights 1000lbs more on the same load.

In the end my comments were more to the lack of consistency of wheel manufacturing I've seen when stud centric mounts were attempted than to get into a deep discussion on shear forces. But it does make for an interesting topic. You seem well verse on this run some loads and let us know.

 

OK, I decided to stay with the rings. Thanks for all the great discussion on the topic.

I bought some anti-corrosion spray and used it to remove two of the rings today. I let them soak for about a half hour then whacked on them with a screwdriver and hammer to get them off. Underneath the rings there was some corrosion and rust so I decided to clean things up a bit.

I first hit the hub with some fine steel wool to remove as much rust and corrosion as possible. Then I masked off the rotor, caliper and studs and painted the hub with a light coat of Rustoleum black. The Rustoleum is supposed to inhibit rust and corrosion so hopefully it will help. It also made the hubs look much nicer after I put the wheels back on.

I used anti-seize on the new rings, putting a thin layer on the surfaces that touched the hub and the wheel. Although these rings are marked the same size as the previous ones (56.1) they went on the hub much easier. So maybe part of the problem was a tight set of rings?

I will do the other two wheels tomorrow and take some photos to post.

 

As stated above, its the static friction between the wheel and hub that holds things in place. If you get anti seize between the wheel and hub bad things can happen.

Alan

 

I guess I wasn't clear...the anti-seize is on the hubcentric ring, on the surfaces of the ring that touch the hub and wheel. This is so the ring will not once again fuse to the hub. The flat surface of the wheel is still being pulled tight to the hub and I did not put anti-seize on those surfaces.

 

Should never happen if the wheels are torqed properly and there is no foreign substance between the hub and wheel.

 

That is correct.

And I'd skip the anti-seize. While most copper/oil based pastes are rated to 1800F, you have no idea if they will run out between the wheel and hub due to rotation, etc.

michael
BSME, Machine Builder in real-life

 

perhaps the studs were fatigued, maybe the lugs were. maybe my torque wrench was out of spec. maybe it was because i didnt have a hubcentric ring on.

a lot of maybes. i dont think it hurts to take one of those maybes away by picking up a set of hubcentrics.

 

I'm prepared to be bashed BUT I suggest you research the entire issue of "hub centric rings" via a Google Search.

In my short search time I saw that wheel manufacturers were NOT calling for these as "required" ......

Some believe the force of a lug/stud is PLENTY to hold the wheel in the right place.

My suggestion: Look more places than here b4 you decide what's right

 

Well, I don't want to have to chisel off my rings and pay $18 for a replacement set each when month I make a wheel change for autocross, so if the anti-seize makes the rings removable as they should be, it's worth it. I put a very thin layer on the rings only. I check the torque regularly (carry a wrench in the boot) and after three days of spirited driving and a lot of highway speeds, the lug nuts have not budged.

Thanks for your opinion.