Drilling for a knurl: learn me converting to different wheel studs

Changing wheel studs on aluminium wheel spacers from m12x1.5 to m14x1.5 

Using these studs

Studs that will be delivered tomorrow

Since i have never attempted anything remotely like this, and Google has just confused the E36 M3 outta me, what/how do i go about this? Is my drill press going to be accurate enough? Or is this a "pay the man " scenario?

Ideally, you'd use a piloted bit.  Something like this in the link but you'll need to find the right sized bit and pilot.  

MSC

That's if you're not changing the bolt circle. 

Wow. 

Is there a way to do it properly without a $40 bit? And how do i determine what size bit i need?

That's odd. Usually Dorman lists the drill bit size with the knurl size.

They used to at least.  The bit size is usually the minor diameter of the knurl.  And yes you can do it accurately with the drill press and the proper bit if you are resizing existing holes. 

I convert lug bolt cars to studs a few times a year and usually use the Jegs house brand studs. The drill bit size is usually on the packaging 

I know when I had to drill out my mustang rotors to the arp 0.625 knurl, I used a 39/64(?)bit and pressed them in. But it’s been awhile...

Yes you just need the correct size drill bit. Those  $40 drill bits are for counter boring like when  you want to use an Allen head bolt and your want it to be recessed below the surface or you just want to make a flat surface for a bolt head/washer to rest on.

the rough approximation for the drill size is 0.008-0.010" under the knurl outside diameter. You are going to need the hydraulic press to get them in if the drill size is any smaller than that.

So it looks like it is the Moroso brand that I usually use that lists the drill size on the packaging. 

Moroso studs with hole size listed

Also found this tidbit from Summit Racing

What size drill bit do I need to install new wheel studs?

To determine what drill size you need, you will need to know:

1. The axle hub material, and
2. The wheel stud knurl diameter.

• If your axle hub material is cast iron or steel, your drill size will be 0.005 in. smaller than the knurl diameter.
• If your axle hub material is aluminum, your drill size will be 0.007 in. smaller than the knurl diameter.

So after some math it looks like a 15.7mm knurl would be a 0.611 hole and the closest I see (using price is right rules) would be 39/64" at 0.609". Get your drill bit, make sure your drill press table is square to the quill and embiggen some holes!

In reply to Jumper K Balls :

I used the 0.008-0.010" undersize knowing that most drills will run a little over the actual drill size, unless you have everything squared up in a very solid setup (mill instead of drill press).

 Awesome. 

The spacers are aluminium. When the studs get here today, ill fire up my harbor freight digital calipers and confirm that advertised specs are the delivered specs.

I also need to confirm that the table is square to the quill on my press.

As far as the head on the back goes: is there a spec that i need to follow, or us the spec "big enough and deep enough to clear"?

Also, wuth where the threaded portion of the stud exits: any specifocs? 

I really want to do it right, as a wheel falling off is not my idea of a good time.

You may need to counterbore/spotface the back so the head of the stud has a flat surface to sit against. I would suggest a very light touch with an endmill of even a carbide router bit big enough to clear the head diameter. I may have the counterbore bit you need and can loan it to you. Give me a call when you have the measurements in hand.

I just helped  our FSAE team install their ARP wheel studs.

The package had the drill size on it. In this case, it was .007" smaller than the OD of the splines.  

stafford1500 said:

In reply to Jumper K Balls :

I used the 0.008-0.010" undersize knowing that most drills will run a little over the actual drill size, unless you have everything squared up in a very solid setup (mill instead of drill press).

I would second this - and I would measure the first few to make sure I am within spec before I ruin all my adapters.   AND if you really want to be right you will drill the hole and then ream it to the finished diameter, if you don't want to be really right, definitely run 1, measure it, if its within spec, run 1 more and measure it, then if that checks out, finish out the rest of the adapter.  I would drill 1 hole and measure it at the start of every adapter just to make sure nothing comes out of spec.  Measure twice and cut once, not a bad idea.

93gsxturbo said:

stafford1500 said:

In reply to Jumper K Balls :

I used the 0.008-0.010" undersize knowing that most drills will run a little over the actual drill size, unless you have everything squared up in a very solid setup (mill instead of drill press).

I would second this - and I would measure the first few to make sure I am within spec before I ruin all my adapters.   AND if you really want to be right you will drill the hole and then ream it to the finished diameter, if you don't want to be really right, definitely run 1, measure it, if its within spec, run 1 more and measure it, then if that checks out, finish out the rest of the adapter.  I would drill 1 hole and measure it at the start of every adapter just to make sure nothing comes out of spec.  Measure twice and cut once, not a bad idea.

^^^ Good advice. I forget sometimes that not everyone has the luxury of a machine shop at their disposal.

We center drilled, then drilled .015" under our final diameter and then used an adjustable reamer to get our final diameter of .620" 

I have always tried to use a reamer when a hole has to be "just this size" and no bigger.