Hole size for .625'' knurl wheel studs [Archive] - Corvette Forum : DigitalCorvettes.com Corvette Forums

: Hole size for .625'' knurl wheel studs


bahamasair
01-13-2008, 02:37 PM
Hi guys.
The title pretty much says it all. I have ARP 1/2" studs for my front hubs, they come with a .625 knurl but I cant find any info saying what size hole I need to drill for them to fit.
Anyone know?
Thanks in advance :)

big2bird
01-13-2008, 05:36 PM
Hi guys.
The title pretty much says it all. I have ARP 1/2" studs for my front hubs, they come with a .625 knurl but I cant find any info saying what size hole I need to drill for them to fit.
Anyone know?
Thanks in advance :)

Well I read the whole Arp website, and the .625 knurl is listed for Ford/Chrysler only.:crazy:

MYBAD79
01-13-2008, 06:07 PM
If you upsize from 7/16" to 1/2" it doesn't really matter if the knurl is for Dodge or Chevy. One important thing is to cheack the length of the knurled area, if for example the hub is 1/2" thick you want the knurl to be 1/2" long so it doesn't protude beyond the mating surface of wheel and hub.... on some wheels the hole might be too small for a .685" knurl so you might have to machine the studs a little.
Measure this before you press the studs into the hub so you don't have to press them out again.

The drill size is slightly smaller than the knurl diameter so it's a press fit, I'm not sure but I think I drilled my front .006" smaller than the knurl. It's a tight fit and I used the nut and washer method to pull the new stud into the hub, took quiet some lube and torque....

lvrpool32
01-13-2008, 06:11 PM
I have the same wheel studs, according to ARP, the drill size should be .02" to .07" smaller than the knurl size.

Nick

bahamasair
01-13-2008, 06:30 PM
Thanks guys Ill be searching through my drill bits tomorrow. I have a new problem now as I reversed over my drill press yesterday lol
I just found this in the faq on ARP's site after reading your replies
"9. What drill size do I need for my wheel studs?

To determine what drill size you need for your wheel studs, you will need to know your axle/hub material and the wheel stud knurl diameter. If your axle/hub material is cast iron/steel your drill size will be .005˝ less than the knurl diameter. If your axle/hub material is aluminum, your drill size will be .007˝ less that the knurl diameter. The Wheel Studs Section in the catalog shows the knurl diameter size"

lvrpool32
01-16-2008, 12:31 PM
I'm having an issue finding a drill the right size to drill these holes....cant seem to find a .620 or .618 drill (has to be hardened because the flanges are hardened(.
Anyone have any ideas?

Nick

MYBAD79
01-16-2008, 01:52 PM
When I drilled my front hub it wasn't all that hard.... didn't use a special coated drill bit either, just the standard stuff they sell at HomeDepot....

big2bird
01-16-2008, 02:03 PM
I gotta ask. How are you guys maintaining the proper hole center's when doing this crap?

turtlevette
01-16-2008, 02:14 PM
I gotta ask. How are you guys maintaining the proper hole center's when doing this crap?

Yep,

as foolhardy as i am i would NEVER attempt to drill out the studs for bigger. I wouldn't trust Norvall's fixture either.

Something that needs to be done with percise machining equipment.

BBShark
01-16-2008, 02:40 PM
I'm having an issue finding a drill the right size to drill these holes....cant seem to find a .620 or .618 drill (has to be hardened because the flanges are hardened(.
Anyone have any ideas?

Nick

The front hubs are cast iron and cut like butter. The flanges for the rear spindles are steel but machine easily. As far as the drill size, I think you might need a 39/64 and an adjustable reamer. A drill and reamer this size is expensive and has a taper shank. This is time for the machine shop. If you could find a drill this size, I sure wouldn't do it by hand.

I sure would check the length of the knurl first also as MYBAD79 suggested. It would suck to do this and find out the flange is not thick enough.

gtr1999
01-16-2008, 02:46 PM
I've been invloved in this as well. I've been trying to find the correct hole diameter for the studs.

Here is what I've found out so far.
ARP told me to go 005 under for any of their studs when used in steel/iron spindles. Go 007 for aluminum. So I asked them what they use for stepping up from a .450 hole. As simple as it sounds I was told a reamer. Now the front hubs are soft but the rear spindle flanges are bit harder and they vary from one to another. Some may be softer others are a job to work on.

The 1/2 studs I show in my posts my buddy drilled out and had me rebuild. He went through (3) HSS bits to drill his. I have faced the flanges in a lathe and they were hard, burned up a carbide tool bit a couple of times. I have an old spindle here and a file cut into it easy.

So back to the 625 diameter ARP's I have. Reamer isn't going to do it and ARP wasn't offering any other advice. The only drill bit I found is HSS and is a 15.75 mm bit at .620" right where ARP said to go. So if the flanges on the spindles I have are not too hard this might be one option.
The second option would be a 5/8 carbide endmill ground 005 under but I don't have one here.

Now some installers just use the next size drill under 5/8" - which is
39/64-(609"). This would put the holes 016" undersize and 008 per side. I'm not sure how much force will be required to press those in, but they won't spin.This for ARP bolts. ARP also had part # 100-7714 with a 554 diameter knurl that a 35/64 bit could be used for and would be easier to source.

www.stockcarproducts.com offers up 1/2-20 studs and those are the ones pictures in my thread on rear brg's.

Moser does as well.

So the question still comes back to hole diameter. 5-8 should work but the tighter holes may be a problem. I will continue to look into this. If anyone has done this recently what did you do and whose parts did you use?

Solid LT1
01-17-2008, 01:24 AM
The quality on the ARP studs is the BEST of any studs but, they can be a real PITA to install! I have done as Gary said and used the 15.75mm drill bits and I will WARN you that when you press in the studs you should find a wheel spacer to keep them aligned because they will walk off center as the splines bite into the soft cast iron of the front hubs. I have had them walk as much as 0.040" and ruin a set of hubs. Again as Gary said the rear spindles can CHEW through drill bits so buy 3-4 bits and do the front hubs first. I would also conside staying witht he 7/16 stud size with ARP parts as these studs are quite a bit better than Doorman stude (what most people re-package to sell as long studs.) If you do this job, have fun, it ranks right up there with heater core replacement on a A/C C3 vette as a job that is a ROYAL PITA to do.

bahamasair
01-17-2008, 05:51 AM
I cant find any bits either. I spent a while last night googling and didn't find a damn thing. We have 1 machine shop here but I doubt they would do anything more than line the holes up and use a drill press so I can probably do a better job myself. I pressed 1/2" studs into my rear hubs from Toms and it was a real frigging bitch. Im sure tom used the 39/64 bit and a couple did go in a little angled but 10 tons of pressure from the press straightened em right out. Ill stop by the machine shop and ask how they would do it and see if I trust them to get it right I guess.

Rip
01-17-2008, 06:58 AM
I've never done this, but it sounds like a machine shop may be the best (safest) way to go since the holes need to stay straight and on size. If someone had brought me this job my first thought would be to chuck the spindle in a super spacer on a mill then use an adjustable boring head with a small carbide tipped boring bar. If everything is trued up in the super spacer and once the first hole is picked up off the existing hole the rest should go pretty quick.
I've been away from job shops for a while and am a bit rusty. Gary may have an opinion on whether this procedure is "doable" on what's needed.

Solid LT1
01-17-2008, 08:26 AM
My friend Dave Herlinger at Corvette Repair in Mtn View, CA has a dedicated jig with drill bushings to drill spindles and hubs. I think he gets around $150 for a car. I will tell you that if you dont have a mill with a Digital Read Out that you can get taken off of the true bolt circle by the serrations the old studs left behind so you can't necissarily pilot off the old hole and drill away and get a true bolt pattern (don't ask me how I know this!) of course the argument is how close do you need to be if the wheel/tire assembly is off? If you want them PERFECT!: Daves number is 650-969-5351 and if you have a couple of weeks, you might want to send him your parts (you may think $150 is pricey but, in my area front hubs sell for $150 or more.)

80VetteGuy
01-17-2008, 10:13 AM
You have to use the Ford/Chrylser studs b/c the knurls are shorter than the Chevy only studs. The knurls would hit the rotor. I have always used a 39/64th bit on a drill press and pressed the studs in on a 10 ton press with no problems.

bahamasair
01-17-2008, 05:14 PM
I think one of the hardware places here has the 39/64 bits. I'm going to do it in a drill press and hope I can press them in ok. Thanks for confirming it is possible 80VetteGuy

tracdogg2
01-19-2008, 08:15 AM
Thgis is the same job I did for 69LUCFER.
http://www.digitalcorvettes.com/forums/showthread.php?t=89685&highlight=tracdogg2
I used studs with a long shank and drilled the rotors .004 larger than the shank. This way the rotors don't sit on the threads. I did have to machine a carbide bit to get the size I wanted.
Mike

gtr1999
02-09-2008, 01:48 PM
I put some pictures on this job in my trailing arm post. The 39/64 bit worked well and the flanges were not hardened like some I worked with.