Need longer wheel studs

[serial car restorer]

A good rule of thumb is to have at least the same engagement as the width of the stud. So for ½" studs you need a minimum of ½" engagement.

 

[ksagis]

Is knurl diameter specified on minor or major diameter?

Seems like one needs two dimensions?

 

[DirtDonk]

Who checks their studs? I bought it about 4 months ago.

Everybody!
OK, well, you’re right. Nobody checks the studs. But everybody should check the lug nuts.
Sounds like yours were covered up by the center caps, so certainly you wouldn’t have noticed them every time you walked up to the vehicle like you would have if they were uncovered. But this is one of those “learning moments” that we’ve all heard about, or experienced.
Anybody that buys a bronco, well, anyone that buys any vehicle, but especially a bronco! And especially if it’s been “restored” or something along those lines. Shouldn’t trust that the previous owner wasn’t a quick flipper and just wanted to get it out and done.

So along with the things like changing all the fluids/oils, even if the seller promised that they had all been done, checking the aforementioned lug nuts, making sure things aren’t hanging low underneath, and if there was a suspension lift recently Install installed, or it looks like the bolts are new at least, retorquing the U-bolts.
Should be done at after a couple of hundred miles of driving. Which of course, almost nobody does.
So after you get the studs dialed in, wouldn’t hurt to check the torque on the bolts.

And unless they had receipts for changing every fluid on the truck, you should at least inspect them. Usually the term “all fluids replaced” means they changed the engine oil and maybe topped off the radiator. Usually doesn’t mean that they’ve changed the brake fluid, or even know how to check the fluid in a transfer case or a differential.

So now it’s all up to the new owner, you.

 

[ksagis]

3/8” of thread is 7.5 threads and 5/8” is 12.5, that would satisfy most use cases for a threaded fastener.

Any thoughts why a lug nut rule of thumb would want 20 threads for a 1/2-20 stud (besides the obvious nasty failure mode)?

 

[toddz69]

Is knurl diameter specified on minor or major diameter?

Seems like one needs two dimensions?

I've always assumed it's the major diameter since that's what creates the interference fit with the hole in the hub/axle.

Todd Z.

 

[toddz69]

Any thoughts why a lug nut rule of thumb would want 20 threads for a 1/2-20 stud (besides the obvious nasty failure mode)?

I've not heard of 20 threads of engagement for a 1/2-20 stud. The usual minimum for that size is 10 threads of engagement (# threads per 1/2" length).

Todd Z.

 

[ntsqd]

In specifying knurls on Engineering drawings the dim is called out on the pre-knurled diameter. If you dive deep into spec'ing the knurling you can specify a minimum or maximum upset diameter but I've never seen that done because knurling is a one-shot deal - you don't usually get to do it again and if you spec the upset diameter and the machinist misses the part is scrap. At most it's usually the pre diameter and a 'tooth' count.

On wheel studs, when I have seen it noted at all, the knurl diameter actually refers to the size of the hole that the knurling is intended to be pressed into.

 

[ksagis]

I've not heard of 20 threads of engagement for a 1/2-20 stud. The usual minimum for that size is 10 threads of engagement (# threads per 1/2" length).

Todd Z.

My bad on math, 1/2” diameter and 20 TPI would be 10 threads. My concussion must be acting up!

 

[ksagis]

In specifying knurls on Engineering drawings the dim is called out on the pre-knurled diameter. If you dive deep into spec'ing the knurling you can specify a minimum or maximum upset diameter but I've never seen that done because knurling is a one-shot deal - you don't usually get to do it again and if you spec the upset diameter and the machinist misses the part is scrap. At most it's usually the pre diameter and a 'tooth' count.

On wheel studs, when I have seen it noted at all, the knurl diameter actually refers to the size of the hole that the knurling is intended to be pressed into.

Let me double check I understand, for a stud spec’d as 0.620”, the hole it is being pressed into would be a 0.620” ID, and I’m guessing if you measured the major on the stud, it would be something over 0.620”?

If I have that right, any idea of what the major on stud would be to create the proper interference fit?

 

[ntsqd]

That is my reading of wheel stud specs. Somewhere a long time ago I found some tech that said that, and I've used it ever since.

The major Ø on knurling is not easy to measure with any confidence. At least not by mechanical means. The stud mfg's likely have their own internal spec for that dim, and the optical means to accurately and consistently measure it.

 

[phred]

I just went through this issue when I put hutchenson wheels on my full size. Here are the stud kits I bought from summit racing. ARP are for the front and the All Stars are for the rear with disc brakes. I would have preferred a 3” stud in the rear but was unable to find one that was press in.

 

[jamesroney]

In specifying knurls on Engineering drawings the dim is called out on the pre-knurled diameter. If you dive deep into spec'ing the knurling you can specify a minimum or maximum upset diameter but I've never seen that done because knurling is a one-shot deal - you don't usually get to do it again and if you spec the upset diameter and the machinist misses the part is scrap. At most it's usually the pre diameter and a 'tooth' count.

On wheel studs, when I have seen it noted at all, the knurl diameter actually refers to the size of the hole that the knurling is intended to be pressed into.

Uhm...yeah. But no.

You gotta be careful when you have a technical discussion with a marketing audience. Engineering specifications regarding knurling are as you described. But in application space, that dimensional feature cannot be directly measured. So you are left with a gross approximation of what the original design intent might have been.

@ksagis and @toddz69 asked a relevant question and that has two answers. From a design engineering perspective, the upset knurl diameter is a result after an operational process. The engineer would specify the shoulder dimension, and the knurl... and the OD is kinda whatever it turns out to be. Since it ends up being an imaginary and arbitrary "best fit circle" with a fictitious center...I don't even know how it would be specified in GDT. But from an application engineering perspective, the nominal upset knurl diameter is a relevant figure of merit. Especially on a fully knurled shoulder...where the entire original shoulder dimension is molested. It's the only thing that the mechanic can measure.

Here is a pic of the Dorman marketing literature for a wheel stud. As you can see in the description and in the spec sheet...the knurl diameter is specified as an OD, and the shoulder diameter is also called out. (.618 knurl on a .610 shoulder) In this case, the hole is actually .610.

Note that this is not a specification drawing. It's a marketing cartoon. But it does denote a "standard. " (...which no design engineer would find useful, relevant, or accurate.)

Cheers.

 

[ntsqd]

I treat them as Engineers. If they aren't and they believe the marketing cartoons (I LIKE that term, I'm going to use it forthwith) then they're on their own. My former employer was internally infamous for those "cartoons". Marketing would take the info that Engineering supplied them and make a product page. When we pointed out that they had distorted the info they were given the frequent comment was "We didn't like that, it doesn't do what we told XYZ that it would, so we changed it."

What I was trying to say about the resulting knurl is that control over the resulting feature is crude, minimal, and can be very difficult to be consistent about. If you're trying to be consistent in knurling on a manual machine, give up. It's hopeless. With a CNC the results are probably more consistent, but unless the drive in that direction has force feed-back (rare) the consistency is only the result of getting to the same place consistently. Still have the material variability that will change the final feature result from one part to the next.

As a friend of TZ's & mine has said "The nice thing about Standards is that we have so many to choose from."
And BTW, anyone who specifies NPSF threads in a pressurized system and then attempts to seal it with an o-ring should just be shot.

 

[nvrstuk]

As a friend of TZ's & mine has said "The nice thing about Standards is that we have so many to choose from."

I'm guessing the pilot you quoted from above but DANG, this is SO GOOD!! lol

 

[ntsqd]

No, he's actually in computers.
Edited to add that he's also an EB owner and on here occasionally. I won't out him, but if he sees this and wants to claim it......

 

[nvrstuk]

No, he's actually in computer

Quote seemed to fit the other one we all know. lol