I'm sure I'm just a bit of a worry wort on it but i have extended studs with 15mm spacers. I feel as though autocross with spacers is not a big deal... however at the track is running spacers a bad thing?

The extended studs provide more than enough threading for the lugs to grab but just thought I would post up and see some thoughts or hopefully get someone with some experience on the matter...

reason being is i just got a stoptech bbk and i now only have one set of wheels that clear without a spacer while my other 2 sets need a 15mm spacer to clear them

 

Nope not a bad thing at all, in fact the way you have done it (extended studs + spacers) is the best way to go. The rationale is that if you use the spacers with integrated studs, you cannot easily re-check torque on those once the wheel is on, so you have no way to ensure the wheel is firmly attached between heat cycles on track.

The final thing i would suggest is making sure you have hub-centric spacers. This ensures that the shearing loads are not actually borne by the studs but rather by the hub ring on the spacer. The studs just make sure full contact of the hub-ring is maintained. This is not absolutely necessary as many have tracked without it, but if you want to be extra pedantic or are having spacers made, its the best way to go.

 

some discussion on this topic:
https://www.s2ki.com/s2000/topic/109...-are-they-safe

 

Spacers can be fine...depending on how they're made and fit. The potential failure is in shear, I believe. Some will argue that the clamping force of the hub secured with lugs is enough to prevent any lateral movement and side loading of the wheel studs, but I'm not confident in that one. The way to do a spacer is with wheel centric and, if possible, hub centric flanges that are interference fit and also ensuring that the bores for the studs are also loose interference fit to the unthreaded part of the stud (again, if possible). That's my take, anyhow, and how I designed the spacers I machined for the Van Diemen Formula Ford I restored a couple of years ago.

Other hand, I've heard plenty of stories of folks running plain old spacers with no problems, as well. Seems ok, as long as the spacer is reasonably constructed and not too big. Constant attention to lug nut torque is indicated...well, it is in any case, but even more so if running a spacer retained laterally simply by the studs...imho, of course.

 

You need to pull the wheels off, torque the spacer down, then put the wheel back on, torque the wheel after every session.

So no, this is a terrible idea. The bolts holding your spacer down will and do loosen between sessions. $.02

 

 

My mistake, I read it as he had studs built into the spacer (commonly used on S2ki)

 

My mistake, I read it as he had studs built into the spacer (commonly used on S2ki)
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thanks guys! the sapcers are hub centric but now that i have the bbk they are only that to the wheel and not the hub... the way the stoptech kit is there is not ring for it to catch on but just a flat surface...

 

I auto-x'd with 17mm extended stud spacers, after two events torque was still at recommended spec, no issues in 4 yrs