Fieros use M12 x 1.75 wheel studs and lug nuts. They are fine for the stock Fiero wheels but when you upgrade to aftermarket wheels with a thicker holding surface, you may lose some of the effective thread length.
This is critical measurement as it not only weakens the lug nut to wheel holding strength; it is also a NHRA rule violation not to have threads within the full length of the lug nut. If you bracket race the tech inspectors will often ask you to remove a lug nut (if it is not the open end see through type) so that they can check the effective threaded stud length. Now comes the question:
Does anyone know what the length of the stock wheel studs are? Does anyone know what the next size up is? If anyone can pass on this info it would save me the time of removing a stud and doing the measurements.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: it is also a NHRA rule violation not to have threads within the full length of the lug nut.

I guess that rules out "tuner" type lug nuts. It is impossible to have threads within the full length of those.

quote Originally posted by Dennis LaGrua: Fieros use M12 x 1.75 wheel studs and lug nuts. They are fine for the stock Fiero wheels but when you upgrade to aftermarket wheels with a thicker holding surface, you may lose some of the effective thread length. This is critical measurement as it not only weakens the lug nut to wheel holding strength; it is also a NHRA rule violation not to have threads within the full length of the lug nut. If you bracket race the tech inspectors will often ask you to remove a lug nut (if it is not the open end see through type) so that they can check the effective threaded stud length. Now comes the question: Does anyone know what the length of the stock wheel studs are? Does anyone know what the next size up is? If anyone can pass on this info it would save me the time of removing a stud and doing the measurements.

Fieros use M12 x 1.50 pitch.

The next size up is Dorman pn 610-323, they are 54mm long.

Confirmed via http://www.dormanproducts.c...ntGuide_pg_10_13.pdf

Archie

quote Originally posted by Archie: Fieros use M12 x 1.50 pitch. The next size up is Dorman pn 610-323, they are 54mm long. Confirmed via http://www.dormanproducts.c...ntGuide_pg_10_13.pdf Archie

Checked the manual and you are absolutely correct M12 x 1.5 is the lug nut size and thanks for the heads up on the longer length studs. With so many guys changing to aftermarket wheels, you would think that this issue would come up more often. Much thicker aftermarket wheels would leave far less thread area than would be advisable, plus the NHRA inspectors at our local track always check the stud thread depth in the wheel lug nuts. Too shallow a fastening length gets you sent on your way! Need to get the car in NHRA compliance with the new wheels.
BTW, I've been following many of your newest projects on the build threads and they are incredible.. You are really taking things to the next level with some of the finest Fieros that I've seen being built anywhere. Beautiful and stunning fabrication and design. Hope to see some of these cars at Carlisle this June.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Not to jack this post, but will these ARP studs work. http://store.summitracing.c...sp?part=ARP-100-7708

I have had good luck with ARP studs in the past. Just don't know if the knurl size/lenght will work. Reason I ask is that I need about 8-10mm longer stud than stock. I will be using a 5-8mm spacer.


Thanks to those who know.

Rob

[This message has been edited by qwikgta (edited 03-23-2009).]

quote Originally posted by TopNotch: I guess that rules out "tuner" type lug nuts. It is impossible to have threads within the full length of those.

Look here, http://www.calwheelaccessor...Path=1&products_id=4 for the open ended tuner lug nuts.

John