HELP Extended Wheel Stud Confusion

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wskirvin

Master Mechanic
May 22, 2017
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Indianapolis, In
I used the 610-323's with the factory rotors so I could bolt on the GTA wheels on the front with wheel spacers pressed right in with no issues
 

DSPbuilt

G-Body Guru
Jan 7, 2016
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Cape Coral, FL
Thanks for the help guys! I ordered the Dorman 610-323 and some hub centric rings. I really wanted to run 3" studs cause the "look cool" but I just want to safely drive the car. I'll worry about getting longer ones when I the rear disk and decide what I am going to do about the front.
 

pontiacgp

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Mar 31, 2006
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Kitchener, Ontario
I would never use Dorman products for wheel studs and the 610.023 have a 0.504" knurl diameter which are too large to fit the .486 " hole. Moroso charts say the interference for a wheel stud is 006-.016 in a steel axle so for G body stud that works out to a .492" to .502"
 

DSPbuilt

G-Body Guru
Jan 7, 2016
568
1,546
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Cape Coral, FL
I would never use Dorman products for wheel studs and the 610.023 have a 0.504" knurl diameter which are too large to fit the .486 " hole. Moroso charts say the interference for a wheel stud is 006-.016 in a steel axle so for G body stud that works out to a .492" to .502"
I've used Dorman studs as stock replacement on other cars with no problem. Again these are also temp.

Numbers seem to be all over the place for this stuff.
Moroso PN:46455 show .509 knurl and listed on Jeg's site "WHEEL STUD & LUG NUT KIT, 12mm x 1.5x 3.25”, .509” diameter knurled stud, 19mm hex nut, Fits: Late Model Corvette, Camaro & Firebird, .482” to .492” "
Press-In Wheel Stud & Lug Nut Kit
  • 12mm x 1.5 x 3.25"
  • .509" knurl
  • Hole Size: .482 to .492
  • For Late Model Corvette, Camaro & Firebird
 

pontiacgp

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81cutlass

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Feb 16, 2009
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I've used those dorman studs on my car and they seemed to press/fit the same as the stock GM ones that came out.

I will be honest, I wasn't a huge fan of the quality of the stud. It didn't have that nice crisp black oxide coating the stock ones did, they just seemed cheap, probably from the zinc coating them had. They seemed to hang up on the lug nut easier also when tightening. The thread form was probably correct but the coating seemed a bit heavy.

I ended up going with these morosso studs for the rear of the car since to be semi drag race legal you need to have extended studs and I swap between shank lug nut wheels and acorn style so having a good strong piece of hardware was important to me.

Plus my moser 30 spline axles came with either screw in or press in holes for the studs. The screw in were 7/16" and since I had metric threads on the front already, and everything I own has metric studs i just wanted to keep it consistent. The moser press in stud diameter was too small for the 0.509 knurl that the morosso studs came with so I use my hand drill and drilled the holes out to 0.5". They pressed in nice with the hole opened up.


I think a 0.509" stud needs a 0.5" hole and the 0.504" or whatever the dorman stud has works OK with whatever the GM stock rotors are drilled for as long as they were metric to start.

I think the ~0.485" diameter that has been thrown out is a 7/16 knurl size and seems to match what the moser axles I bought had, since that hole was way too small for the M12 knurl.

Dorman studs are $12 for a set of 10, Morosso studs are damn near $70.
 
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81cutlass

Comic Book Super Hero
Feb 16, 2009
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Gm 9599302 is the OEM part # same as the dorman, and seems to have a higher quality zinc flake coating more similar to OEM than the Dorman studs.

~$35 for a set of 10.

If I were to do it again I would try the GM studs. I think its worth $20 to get nicer studs over the dormans especially if you swap tires often. I don't think I'd pay the additional $60 for morossos.
 

mikester

Comic Book Super Hero
Mar 10, 2010
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Small town NY
I guess Im the only person that had bad luck doing new studs.
I wanted new longer studs put in the slotted rotors on my 81. I got tired of fishing for the short studs with the Weld Draglites on the car. Went to a local speed shop with one of the studs that I pressed out of them. Owner took a caliper, measured the old knurl, measured a new Moroso and told me they were the right ones. I took them to work and used a press to put the first one in. Cracked the rotor at the hole. Went back to the shop and got into a scream fest with the guy and he says I should have measured them myself before I pressed it in.
Bought a replacement rotor. Found a guy that built race cars and did fabrication work. He drilled and pressed new studs in the axles. Perfect job. Three weeks went by and he didnt have the rotors done. Five weeks after I dropped the stuff off they were done. Since he screwed up the paint on the hub I started to strip it off thinking I would just have to spray them again. Once the paint was off I could see hairline cracks in the hub at every stud. At that point I was a lunatic. The guy made all sorts of excuses. Said he would pay for a new set of rotors. Kept telling me he ordered them and they were on the way. Well, you can imagine how that turned out.
In the end I bought a set of Delco rotors. Took them to a local engine builder and he drilled them a hair bigger and pressed in new longer studs for $100 and I had them the next day.
 

DSPbuilt

G-Body Guru
Jan 7, 2016
568
1,546
93
Cape Coral, FL
I've used those dorman studs on my car and they seemed to press/fit the same as the stock GM ones that came out.

I will be honest, I wasn't a huge fan of the quality of the stud. It didn't have that nice crisp black oxide coating the stock ones did, they just seemed cheap, probably from the zinc coating them had. They seemed to hang up on the lug nut easier also when tightening. The thread form was probably correct but the coating seemed a bit heavy.

I ended up going with these morosso studs for the rear of the car since to be semi drag race legal you need to have extended studs and I swap between shank lug nut wheels and acorn style so having a good strong piece of hardware was important to me.

Plus my moser 30 spline axles came with either screw in or press in holes for the studs. The screw in were 7/16" and since I had metric threads on the front already, and everything I own has metric studs i just wanted to keep it consistent. The moser press in stud diameter was too small for the 0.509 knurl that the morosso studs came with so I use my hand drill and drilled the holes out to 0.5". They pressed in nice with the hole opened up.


I think a 0.509" stud needs a 0.5" hole and the 0.504" or whatever the dorman stud has works OK with whatever the GM stock rotors are drilled for as long as they were metric to start.

I think the ~0.485" diameter that has been thrown out is a 7/16 knurl size and seems to match what the moser axles I bought had, since that hole was way too small for the M12 knurl.

Dorman studs are $12 for a set of 10, Morosso studs are damn near $70.
I don't know why I didn't just think to drill them out with a 1/2 inch bit... I just canceled my order from Summit and ordered the Jegs extra long studs. I may run a hub centric spacer in the front to clear the brakes I'm piecing together.
 
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pontiacgp

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Mar 31, 2006
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Kitchener, Ontario
I would pay the extra $60 for quality studs that I view as a safety issue which works out to $1 per month if you change them after 5 years.
 
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