Wobble bolt, how safe is it?

How safe is wobble bolt? The use case is 4X100 wheels (e.g., Kosei, Enkei and Rota) on Abarth 500 with 4X98 bolt pattern assuming I'm using the right size bolt and hubcentric ring. Is it safe for daily drive and occasional autocross? Thanks guys.

Back when I was autocrossing- none of the DCSCC clubs would allow wobble bolts.  At least that I am aware of.

Not quite as bad as slot mags, as there was a very specific rule pointing those out.

I'd be weary of the hubs to be actually hub centric- on my Alfa, I've had people suggest that they could put hub centric wheels on them- but the lip on the axle is comically small to be able to take those loads.  All the loads go through the lugs.

RX-7 people have used those to put Ford 4x4.25 (108mm) wheels on 4x110 hubs, but it always gave me the heebie-jeebies.

I wonder if there's enough material 45 degrees off of the 98mm bolt pattern to drill and tap for a 100mm pattern.  Can't remember if the Fiats have flat-backed hubs, scallop-backed hubs, or just simple skeletonized crosses.

I actually don't see a safety issue as long as the the wheels are hub centered and the bolts are then used only for clamping.

EVERYONE SAY IT

wobble bolt
wobble bolt
wobble bolt
wobble bolt

on the alfa romeo bb,, a german guy says there ok for use in germany  ( 164 car and gtv ' transaxle type' and milano ) to fit diff. wheels.   and you dont want to even try to pronounce  in german.. he said.. if you drink a few beers its easier to pronounce

In reply to alfadriver (Forum Supporter) :

americas tire sell plastic concentric spacers..i have them on my spider

Sidewayze said:

I actually don't see a safety issue as long as the the wheels are hub centered and the bolts are then used only for clamping.

Here's the thing- if the lugs don't line up, the wheels are not designed for the tire- so what are the odds that the hub matches up correctly?

Alfaromeoguy said:

In reply to alfadriver (Forum Supporter) :

americas tire sell plastic concentric spacers..i have them on my spider

If you are willing to load your wheels with a piece of plastic where the load path is, well...  Not something i would be willing to do.  The compression will let the wheel move relative to the hub, which will also release some tension on the bolts.  And over time, that could also loosen the bolts.

Not for me.  Given the option of getting the right designed wheels....

I had 150,000 miles on mine between 112 wheels on a 114.3 and/or adaptors. Center with a hub centric ring and tighten slowly in a star pattern. 

I autocrossed with them for 8 years on a FB with Mustang wheels. I didn't have any issues with them. I turned a set of centering rings on the lathe to keep them centered and checked the torque regularly.  

My son uses them to run 4x100 rims on his 4x98 Fiat 500. No issues in over a year of commuting 110 miles daily. He uses the plastic centering rings and a torque wrench to tighten them.

For cars that have it, the only load the hubcentric interface carries is the weight of the wheel/tire during installation. It's basically just to making proper wheel installation easier on a high speed assembly line... To the side-benefit of those less mechanically inclined. Standard conical bolts without a hubcentric spacer can still get to the same end results without the hubcentric interface, it just takes more time/care/effort/skill, and therefore cost in production.  This is why plastic hubcentric spacers on aftermarket wheels with the correct bolt pattern are more than adequate.

With wobble bolts though, the hubcentric ring is an important piece of of their functionality. However, once the bolts are torqued, the wheel face and hub face are mechanically locked. If not, you have an entirely different problem on your hands, that is not unique to wobble bolt applications.

Admittedly, if using wobble bolts, I'd go for the machined aluminum hubcentric spacers. They're more likely to have better concentricity and tolerances than injection molded plastic.

There are TUV approved wobble bolts, if that tells you anything about their safety/effectiveness when made and used correctly.

In reply to Driven5 :

Thank you!!!

I'll allow that any concentric ring that would actually be load bearing would need to have a significant press fit.  Otherwise it is like the locating tang on a bearing shell: it is only to make installation easier.