Hub-centir; Lug centric
 

I thought there was a pre-existing thread on this, but the search engine did not turn it up. Anyway, here is a tidbit from the Yokohama Tire manual that might be of interest to someone.


http://forums.pelicanparts.com/uploa...1127706330.jpg

lug centric does not work on german cars, all german cars are hub centric, Kevin

There are enough examples of German cars...without studs...and without a center bearing surface ( old air cooled VW's come to mind, especially for the front wheels), that there is no inherent hubcentricity...and the warning for lug-centric applies.....

...no? ....

Wil

this seems to only explain the different concepts which is nice, but what i'd like to know is how people avoid/get around this problem when using small spacers? (4-6mm)

do they just ignore it?

I have been working with wheels and tires for 25 years, if you dont think you need hub centric on a german car go for it, ill wait for your why is my car shacking post

i agree with that, but i'd like to know how all the people running spacers have avoided this. do they have an ongoing conspiracy to not tell us?

Randy,

Clearly all the wheels are lug-centric prior to ’74. With ‘74-> having both the ball-type lug nuts and the hub centering device, which method takes precedence?

Best,
Grady

No wheels on any car have to be hub centric. If they did you'd only need one lug nut. It is a really nice and professional touch but not manditory.

Lug centricity simply means that the person who mounts the wheel is now responsible for the hub fitment and balance.

With 911s that use an "acorn" style nut you simply start all 5 and tighten them up in a rotated fashion until all are perfectly seated. Period. I have used spacers for decades with no problems at all. You have to take your time and do it right, just like everything else in life.

If you have the option of hub centricity take it, but don't freak over using spacers that negate hub centricity.

Grady,
can you explain what makes you say that?

This is to funny I give up

I have .375" spacers on the front of my car (effectively making the wheels lug centric) and have never had any vibration problems as a result. No conspiracy.

Mike

"which method takes precedence?"

- Dunno. Whenever I had a choice, I think I'd try hub-centric first b/c of the advantages listed in the Yoko manual...

Using spacers for 15 years on 911's on and off the track with no vibration issues, etc. I try to use factory spacers, which retain the "hub centric" raised center ring, and I never use bolt-on spacers. But I often have to make small adjustments with 1/4" spacers - never a concern. Just tighten in the proper fashion and drive on.

Chris

I'll throw this out there...

Could cracked fuchs be caused by the use of slip on spacers? There's no doubt in my mind the loss of support on the center of the wheel has to have some effect, even if you center the wheel properly with just the lugs.

The last cracked Fuchs I saw came from a friends car with no spacers. I think this is just old metal, used non-stop for too long in a demanding application. Overtourquing could certainly hasten the demise!

Perhaps it was my thread
 

I recently started a thread about hub centric and wheel centric. Ernie's Alloy's in Miami explained that hub centric meant that the back of the adapter was machined to fit tightly over the small lip sticking out of the hub. The other side of the adapter has a lip sticking out from it that fits into the back of the wheel. Without these two machined in elements the wheel could be slightly off center and hop at high speed.

Now lug centric is another whole ballgame. I noticed that even when I bought the expensive adapters (both hub and wheel centered) that the lugs were not exactly in the middle of the holes in the adapters.

Just thinking out loud here ….

Do Fuchs get cracks on 911s with the centering hub? Could there be extra stress from the lug nuts trying to center a wheel that is being centered by the hub?

2c

Best,
Grady

It should not be a given that your wheel will be off center if not using a hub centric design. All 5 lug bolts carriers are also precision machined to balance the wheel. Hub centricity and lug centricity should work in concert, not be mutually exclusive. There should never be a "tug of war" going on between the lug nuts and the hub.

The only reason I can think of for any lug centric wheel to be out of balance is operator error. By this I mean that the lug bolts were not pressed in correctly or the lug nuts were not tightened correctly or both.

A hub centric design is prefered to lug centric if you have the option. If you do not (such as when using spacers), just make sure the bolts and nuts are properly assembled and alligned.

I would say that by definition my cup car wheels (centerlock) are Lug centric, as they ride on the 5 short pins where the studs would normally be.

Torque lugnuts properly, make sure the mating sufaces of the hub/wheel/spacer are clean and smooth, and you have enough threads engaged if you are using spacers.

I also prefer steel lugnuts for the track.

I hope the wheel stud circle is concentric with your hub....otherwise Porsche has a lot of splaining to do :D