AFX spindle and 1/2" wheel stud

[79T/Aman]

BTW Mr. engineer there is no way you could press fit a stud with nearly 1/8" interference without distorting or cracking the hub, one thing I take offence to is narcissistic engineers that think they can pull the wool over other people's eyes.

[DriverzInc]

My car has had 12mm front and 1/2 rear since it was built. They are both 13/16 and the lug nuts say what thread pitch they are. I usually throw the 1/2 inthe rear of my seat tray and the 12mm's in the front. Marginally easier to have 1/2 all the way around.

Dude, you and I think alike.

[GrnDragon]

I'm not sure I can deal with having 12mm and 1/2 studs front to rear, just a "MENTAL" thing.

So I called the ARP Special Order group and explained this situation and let them know if they made a 1/2 stud that had a .509 knurl diameter they would probably sell like hot-cakes.

I know the .509 dia is small and not nearly as strong as the .625 knurl dia of the 7703's but it would eliminate the need to have any machining done.

I'll update when I get an answer.

[killer69]

Dude, you and I think alike.

thats what is did, if i could order 12mm screw in studs for the axles i would just to that.

[mrengineer]

Photos will be awhile, I am in Chicago for work.

[68sixspeed]

I've got possibly a dumb thought, could there be any problems from the GM 120mm bolt circle vs a 4-3/4" rim bolt circle (.026" difference) ? Or are the bearings special ordered on 4-3/4" bc?

While reworking the hubs it would seem like a logical time to fix the bolt circle too, correct?

[brakenit]

BTW Mr. engineer there is no way you could press fit a stud with nearly 1/8" interference without distorting or cracking the hub, one thing I take offence to is narcissistic engineers that think they can pull the wool over other people's eyes.

But he's not just ANY engineer, he's Mr. Engineer.

[Apogee]

I've got possibly a dumb thought, could there be any problems from the GM 120mm bolt circle vs a 4-3/4" rim bolt circle (.026" difference) ? Or are the bearings special ordered on 4-3/4" bc?

While reworking the hubs it would seem like a logical time to fix the bolt circle too, correct?

The C5/C6 Corvette wheel pattern is 5x4.75, not 5x120.

[GrnDragon]

I have always seen the bolt pattern referred to as 5x4.75 or 5x120.65, so it is a "square" 5x4.75. It's just VERY confusing why GM does a 5x4.75 bolt pattern with a 12mm stud????

I asked ARP special order group about just threading their 7708 and 7713 with 1/2-20 instead of the 12mm-1.5 but they were not very receptive since I would only be buying 10 of them.
They might consider it if a vendor contacted them and could buy a couple 100-1000 to sell to us....

I have been seeing torque specs for 1/2" lug nuts is 80 ft-lb and 12mm lug nuts is 90 ft-lb from a couple different sources. Is this what others have found? It seems opposite?

[CamaroAJ]

GM says 100ft-lb on all of there cars with 12mm studs.

[killer69]

GM says 100ft-lb on all of there cars with 12mm studs.

your refering to the wheel torque i am guessing

[68sixspeed]

The C5/C6 Corvette wheel pattern is 5x4.75, not 5x120.

that's good, I had been told by another vendor that they were 120mm, but you are correct, I searched and found 120.7mm = 4.75" ... solves another question on another project!

[killer69]

did we resolve this issue Mr Engineer.

[TitoJones]

Tyler - I wish you did not make the claim in the previous post. The holes were not milled - there is evidence to prove a milling operation was never done. I know what I measured both on the hub and stud. I also I know what milling marks leave behind when magnified under microscope. You also never claimed to mill prior to installation only until now. And your invoice never stated milling maching operation whatsoever prior to stud installation! I don't care to get in a debate but please do not tell people you milled the hubs prior to installing studs, unless you can prove it. My profession deals with facts and not assumptions. In fact the new supplier of AFX spindles sent me an e-mail stating they will no longer continue the practice to install different studs because of the liability and the facts presented to him when we talked. Enough said.

I'd like an apology for this bullsh*t post. You are calling me a liar and claiming I didn't do what I've done for every single set of upgraded hubs we've ever sold. It is not physically possible to install the 1/2 stud by hand in the arbor press if the holes were not milled. I know for a fact the rotor caused the back out issue because it was not designed for a 1/2 stud, and you did not check the seating against the hub before driving the car.

You may be an engineer, but you installed a rotor designed for a much smaller stud and didn't check your installation properly before setting out on the road. Engineer does not equal competent car builder.

Tyler

[mrengineer]

It is unfortunate you can't be rationale, objective and professional in your PM messages to me. I don't care to talk to you or debate what you claim was done. Remember you advertised a product, sold that product without properly engineering it and then blame the customer when there's a problem with its application or usage. I suggest you become more familiar with product liability in the future.

[eville]

Mr. Engineer.
Can you post some pictures so those of us in a similar situation can see how your issue might compare to ours.
Also can you please confirm that you had your rotor holes enlarged?

Just looking for the truth between to passionate sides.

Thanks.

[TitoJones]

It is unfortunate you can't be rationale, objective and professional in your PM messages to me. I don't care to talk to you or debate what you claim was done. Remember you advertised a product, sold that product without properly engineering it and then blame the customer when there's a problem with its application or usage. I suggest you become more familiar with product liability in the future.

Lets just stick to the facts at hand here.

#1. All ATS upgraded hubs get done the exact same way, by the exact same machinist, in the exact same machine, with the exact same tolerances, and the exact same parts.
#2. There is NO possible way for the 1/2 ARP stud we used to be installed in to a NON machined hub. It will not fit. The machinist I employed to do this upgrade installed each stud by hand with a manual arbor press and then straightened every set after installation.
#3. We employed a degree holding mechanical engineer who worked for OEMs, aftermarket companies (including DSE and Scott Drake enterprises) who gets mine and multiple other engineers full confidence.
#4. ARP was the one whom specified the proper hole sizing which falls in between known drill bit sizes; hence the required milling operation to get the exact interference press fit. Furthermore ARP manufactures the stud that holds the bearing pack to the AFX forging; we worked very closely with them on this project.
#5. The knurled portion of the studs protruded past the face of the hub which will cause all C5/C6 rotors NOT to seat properly as they were NOT designed for anything other than the factory 12mm stud originally installed.
#6. You cannot/have not provided any info refuting this with pictures, measurements etc. I asked for a picture of your hubs with a set of calipers measuring the hole. I asked for pictures of the back side of your rotors. I asked you to tell me whether or not you clearenced your rotors before installation and driving on them, which you have refused to answer.

You claim we didn't properly engineer these things? Prove it. Get me hard data with facts, pictures, failure points, CAD data and anything else you can to prove your point. YOU are the one making claims. I had product liability insurance when I owned and operated ATS. You want to take this to court? What you are trying to slander me with is that we did not do what we have always done. We installed the studs properly into a very well engineered product (which you willingly purchased as an engineer yourself) in accordance with the manufactures required instructions (in this case American Racing Products) and then delivered to you for final installation onto a road going vehicle. You performed the installation of the AFX spindle, the brake system, (which includes the rotors that caused the stud back-out issue) the wheels, and then finally the lug nuts. You're claiming faulty and improper stud installation by way of non-machining and incorrect tolerances. I'll easily back up my product, techniques, procedures, machining tolerances, and installation of said stud to any court. Can you prove to them that it was not the installation of your rotor that ultimately caused this back out of the studs? I highly doubt it.

Here is what I'm blaming:
The rotor holes not being the correct size for the upgraded stud. Not you, not the stud, not the installation of the stud, or our engineering of the product from scratch. I know, and you by now MUST know that the rotor you installed was designed (or your favorite term to toss around like a god, engineered) to work on a factory C5/C6 Corvette hub which at no point was ever equipped with a 1/2 stud with an even larger splined shank protruding into the face area of the hub.

Here is the area I'm talking about:


Here is the factory stud:


Notice the difference? A rotor slides and seats easily over a factory stud. The rotor slides over but stops on the 1/2 shank yet appears to seat to the untrained eye. Later as the wheels are installed and the lug nuts torqued the studs begin to back out and we have the issue that you experienced first hand.

Does this mean ATS installed the ARP stud wrong? Of course not. Does it mean we didn't mill the hubs as we have always done? Of course not; you wouldn't even possess an ARP upgraded 1/2" stud AFX spindle if we didn't mill it as we couldn't install the damn thing into the hub otherwise.

Why can you not see that you had an issue related to the stud shank not allowing the rotor to seat, and not the stud installation itself and leave it at that?

You might not like my tone, but I don't appreciate you mis-representing the facts. I've brought my tech, now you better bring yours, or you better retract your statements.

Tyler

[1badchevelle]

Well said Ty, as simple as it is that is what tends to be over looked.

I guess a degree sometime lacks common sense.

[BrianP]

Judge Judy here,
After looking at the photo evidence submitted by the defendant: It's pretty obvious that the rotors will cause the studs to back out if they are not properly re-sized to avoid the 1/2 inch stud's fillets.

Case Closed.

Bailiff, Please seize a set of those AFX spindles for.... a... research, yeah.... research.