hubcentric adapter question

[E. Roy Wendell IV]

On Jan 24, 2007, at 6:12 PM, LL - NY wrote:

> On 1/24/07, thejimrose <thejimrose at gmail.com> wrote:
>>
>> i almost got this.
>>
>>> Bolts really don't hold the wheel. They apply tension force  
>>> between the
>>> wheel and hub which increases the friction between the wheel and the
>> hub.
>>
>> so the bolts hold the wheel to the hub...
>>
>>> So, there is ALOT more availible force from the preload between  
>>> the hub
>> and
>>> wheel than any little hubcentric lip would create.
>
>
> The lip just ensures that there is a mutual axis. Essentially a  
> guidance
> jig.
>
> FRICTION is what is really transferring torque and lateral loads  
> between the
> wheel and the hub. Frictional force is proportional to the clamping  
> force
> between the hub and wheel, and the coefficient of friction between  
> them.
> More clamping force, more friction, more load margin. That is when  
> the more
> massive or powerful cars go to more and more wheel bolts (think  
> Viper),
> since clamping force goes up in direct proportion to the # of wheel  
> bolts
> (assuming the same tightening torque and thread pitch). Yes, in  
> reality, the
> centering ring does carry a tiny bit of the load, as do the lug  
> bolts/lugs
> just because they are in the way. However, a for instance: My  
> former SCCA
> Solo2 GTi (and nearly every competitive Solo2 Neon back in the  
> early Gen1
> ACR days) ran on American Racing AR24s. Light, correct size and  
> offset to be
> legal. Cheap due to an SCCA discount. And not even fugly. Hence  
> TONS of them
> around. Both in Solo and Club Racing. Wheel to Wheel.
>
> They used nylon centering rings, as do ALL American Racing rims,  
> for both
> cars and light trucks. Think American Racing, SCCA or their insurance
> companies would trust nylon to carry torque or radial (transverse)  
> loads?
>
> Or, for that matter, 4 half inch diameter shafts with rather extensive
> stress risers (threads)?
>
> you lost me. i thought that the hubcentric ring is there so that there
>> IS force applied from wheel to hub. otherwise there's an airspace and
>> the hub/wheel aren't touching and only the bolts are holding things
>> up. no bueno, methinks.
>>
>> That being said, without
>>> the hubcentric lip in contact with either the wheel itself, or
>> hubcentric
>>> rings, it could be rather difficult to ensure that the wheel and  
>>> the hub
>> are
>>> sharing the same rotational axis.
>>
>> right. if everything's centered the wheel spins in something more
>> closely resembling a circle. which mine definitely are not since i  
>> got
>> no ringy dings.
>>
>
> IF your rims use conical style lugs, you may be able to center up  
> the wheel
> without the use of the centering ring BTDT. Mount wheel (a real  
> pain without
> the ring, I might add), and lightly tighten the lugs, rattling the  
> wheel as
> you tighten in proper sequence, over and over again. Helps if you  
> can rotate
> the wheel/hub to even the load, but being that you're quattro, this is
> unlikely.
>
> The LUGS conical section will help center the wheel IF the lugs are  
> properly
> located. And remember, its the pressure of the lugs that mostly  
> define the
> radial/torque loads carried by the wheel, not the shear loads of  
> the lugs or
> rings.
>
> LL - NY

Hmm, I find this highly interesting. For years now I've been thinking  
that the aftermarket wheel companies have been selling dangerous  
products by sending them out the door with plastic hub center  
adapters. I was under the impression that with stock wheels the hub  
center was carrying all the radial (vertical) loads and the bolts/ 
studs all the axial loads. Now you say that friction does it all,  
which I can sort of understand but what about the following scenarios:

1. You coat the hub to wheel interface with anti-seize compound.
2. The wheel is powder coated on the hub mating surface (most are).
3. A couple of the lug nuts/bolts get loose.

All of the above apply to me with various cars at various times. Most  
recently, I started getting a vibration in the steering wheel after  
about an hour on the interstate. While driving slower on the off ramp  
I notice that the vibration is more pronounced when turning one  
direction vs the other. After getting all worked up thinking about  
all the time and money I spent rebuilding the entire front end  
including wheel bearings I realize that I should start with the  
basics. So I stop in a parking lot and check the torque on the lug  
bolts. Holy crap, one bolt is missing and only one of the remaining  
four is really tight. So I do the best I can and tighten the four  
bolts I have and drive another hundred or so miles to get home where  
I have a handful of spare bolts. The one time I don't check up after  
my alignment shop by torquing my lug bolts in their parking lot and  
this is what happens. Lesson learned there. But if I had been using  
aftermarket wheels with plastic non load bearing rings do you really  
think the wheel would have stayed on long enough for me notice the  
vibration? I don't. I still feel that plastic centering rings are  
absolute crap. You may be right that during normal operation friction  
between the wheel and hub faces carries all the load but there's no  
way that a plastic ring does the job in the event that something  
isn't quite right.

Roy Wendell
erwendell at mac.com
Too many type 44 tq
A pair of MR2s