FlyYellow

I just purchased some 8mm wheel spacers (the ones you get off the older 911's). I'm trying to determine if I need to change the studs? How many turns on the lug nuts do you need to insure safety (for autocross purposes as well)?

Any inputs would be welcome.

Cheers,

Boris

Adrian

Dear Boris,
6mm is the limit here in Europe. A 7mm spacer requires studs under TÜV (German) and the Swiss authorities,
Ciao,
Adrian
911C4

Jeff Curtis

Boris, 8mm is quite the sacrifice in threads. You will certainly need longer studs by anyone's standards. Get a steel lugnut from somebody that races/attends DE and you will see how much you are giving up...I'm wondering if you will even engage ANY threads??

Jim Michaels

My understanding is that for proper thread engagement using the OE alum lug nuts, a thread engagement of 1.5 times stud diameter is required. If factory steel lug nuts are used, only 1 times stud diameter is needed. If that is indeed the case, I believe that longer studs would be called for using alum lug nuts, and engagement using steel lug nuts might be "marginal." The previous owner of my tracked and autocrossed car used .25" (about 6 mm) spacers in the rear with OE studs and OE alum lug nuts. While he apparently didn't have any problems with that (as I recall, that gave about 7 turns of engagement), I got both longer studs and steel lug nuts because it makes me feel more comfortable. I went up to the next offered stud length over OE (can't remember the length; 56 mm?), and they stick through the lug nut about 3 mm. BTW, I suggest ordering factory steel lug nuts, as I've seen aftermarket lug nuts that didn't have quite the right shaped shoulder to fit firmly against the wheel.