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#1067290 - 07/14/20 03:49 AM 8.5 & Kore3 disc upgrade and studs  
Joined: Jan 2005
Posts: 136
8T7AERO Offline
8T7AERO  Offline

Joined: Jan 2005
Posts: 136
Corona, CA
I'm upgrading my 8.5 with a Kore3 kit that uses Wilwood C6 calipers and rotors. The instructions says to upgrade the studs with longer/stronger studs, that's where I'm confused on what studs to use for the upgrade. I contacted ARP to see what options they have for a 8.5 rearend, here's the list of studs they have ARP-100-7726 Late model GM M12 X 1.5 X 2.0 , ARP 100-7725 Late model GM M12 X 1.5 X 2.5 , ARP-100-7708 Late model GM 12M X 1.50" and ARP-100-7713 Late model ,Camaro,Firebird, Corvette M12 X 1.50 , to be honest I don't have clue what all this means and I reached out to Kore3 for help, but haven't heard back yet. If any body can please give me some guidance I would be very thankful. Keith

87 Aerocoupe, Rapp Racing 383 with AFR aluminum heads.Leather interior,Hedman headers,Flowmaster Super 40's, k&n filter,MSD Ing, 17x8 IROC w/ 245/45/17, Wilwood front & rear disc brakes, UMI Performance Stage 2.5 suspension, Kenwood sound system..
#1067291 - 07/14/20 05:02 AM Re: 8.5 & Kore3 disc upgrade and studs [Re: 8T7AERO]  
Joined: Jan 2000
Posts: 4,863
mmc427ss Online content
20+ Year
mmc427ss  Online Content
20+ Year

Joined: Jan 2000
Posts: 4,863
Pottstown, Pa
The type of lug nut, blind or open and what you are going to do with the car makes a difference. Blind lugs require a specific length studs, so they don't bottom out on the nut. If you drag race tech likes to see stud projecting out of the open lug nuts if you run slicks.
The thickness or your new rotor verses drum thickness will determine stud length change needed.

The ARP stud installed in my Moser axle 8 1/2" are number 100-7708 which are 2.5" long. A stock stud is a little less than 1.6" The important measurement is the .509 knurling OD, and the .315 knurl length, used on the older GM 12mm studs. This narrows down available candidates.

My combo is unique to my 8 1/2", alum drums which have a .100" thicker flange than cast iron and a hub centric 10mm (.394") alum spacer that allow three different tire sizes to bolt right on, no rubbing.
The slicks are on 15" steel rally wheels with standard open studs. Steel wheels are much thinner at the flange so for drags 2 or 3 threads show past the lug nut.
Street wheels use an open GM lugs that have the plastic covers screwed onto them, F-body. Stud is just to the top of the lug, 100% thread contact, covers fit no problem.
Autox wheels are the same as street but tire is fatter, 275/45x16 Hoosier. The combo of stud length, alum drum, 10mm spacer all work together and optimize each wheel/tire combo, no rub.

So now that you are more confused, measure the thickness of the old drum, the thickness of the new rotor, the difference will be change in threads into the lug nut. I like 100%, I've seen some say you don't need 100%.
ARP makes very good studs, shouldn't be China like all the other offerings, Dorman, Raybestos, NAPA, whoever.

First time I put Moser's in the 8 1/2" I used the standard length Dorman, they were fine. Second time was an upgrade to 30 spline Moser/Truetrac and QTP bias slicks.The choice was the 100-7708 because they were the exact sizes to press right into a new set of Mosers. No cutting! Just a little more piece of mind.

#1067292 - 07/14/20 01:22 PM Re: 8.5 & Kore3 disc upgrade and studs [Re: 8T7AERO]  
Joined: Jun 2006
Posts: 1,790
Travis Jones Offline
10+ Year
Travis Jones  Offline
10+ Year

Joined: Jun 2006
Posts: 1,790
Ferndale, MI
Be mindful that with semi floating C-clip axles and fixed rotors you will experience pad knock back.

86 SS 6.0L LQ4, TBSS intake, Summit Stage 3 NA Cam, Stainless long tube headers, Stainless 3in exhaust, Microsquirt ECU, FABbot AR5 5-speed, Eaton Truetrac 8.8 LSD, QA1 Lvl 3 Front Suspension, 3-link Rear suspension w/ UMI Control Arms, UMI Front & Rear Braces.

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