Upgrading to 1/2" studs

Yellow73SB

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Mar 24, 2008
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Heres the specs of the studs I found

Wheel Stud Style: Press-in
Thread Size: 1/2-20 RH in.
Knurl Diameter: 0.615 in.
Underhead Length (in): 3.000 in.

What bit would I drill the holes out with?
 
.625 (5/8). Use a big, variable speed drill, cutting fluid and make sure you have some kind of jig with a drill bushing to keep the bit perpendicular. Oh yeah, make sure the drill doesnt plunge and twist your arms off;)
 
39/64" is roughly .609" which gives you only .006" interference (knurl .615").

Sometimes the metric system is your friend:

A 15.25mm drill is .601" which is very tight, I am not sure if 15.30mm drills are available. Check McMaster, good luck.

Measure the knurl, maybe it's a litle smaller than advertized size.
 
I believe the hole is supposed to be .006-8 under the knurl size (ARP site). It's going to be difficult enough to find a 39/64 with a 1/2 shank. Finding a fractional metric drill that big without a taper shank is going to be even harder.

I sure wouldn't try this without a bushed drill fixture.
 
Here's the solution: adjustable reamer. You drill 19/32" (.593") and then open the hole with the reamer to .607" or knurldiameter minus .008".

McMaster part number 3141A14 this reamer is adjustable from 19/32 (.593") to 21/32" (.656")

It's not cheap and it will keep you entertained for a while.
 
Moroso wheel stud selection:

46180 Wheel Studs—1/2"-20 x 3" Press-in, .615" dia. knurl and quick start dog end, fits most disc brake Fords front and rear and Chrysler front. Standard hole size: .606" to .613"
46185 Wheel Studs, 1/2" -20 X 3" Press-in, .594" dia. knurl and quick start dog end, fits 1979-03 Mustang. Also has flat on head for front hubs with ABS. Standard hole size: .580".
46190 Wheel Studs—1/2"-20 x 3" Press-in, .685" dia. knurl and quick start dog end, fits most Chrysler rear with 1/2" stud. Standard hole size: .676" to .683"
46220 Wheel Studs—1/2"-20 x 3" Press-in, .563" dia. knurl and quick start dog end for use in 1/2" Frankland hubs. Standard hole size: .554" to .561"
 
You might try Guldstrand, he used to sell 3" or 3.5" long 1/2" studs and long lug nuts....you might also ask Liverpool/Nick with the yellow coupe at the other place, I recently sold him a set of long 1/2" lug nuts so he obviously must have found the correct 1/2" studs..............redvetracr
 
Bisco of Florida (Fort Pierce) has almost all sizes of reduced shank bits in 1/2" shank up to 1.5 inch.
1-866-247-2635

1/2 shank x 39/64 in HSS is $10.56
in Cobalt is $18.89
:D
 
Heres the specs of the studs I found

Wheel Stud Style: Press-in
Thread Size: 1/2-20 RH in.
Knurl Diameter: 0.615 in.
Underhead Length (in): 3.000 in.

What bit would I drill the holes out with?


this is something i won't try myself and i do everything to my car. I've never been able to drill a hole perfectly straight and get it perfectly centered and it has to be for the wheel to go on right.

i bet you a dollar you f it up.
 
All you need is this:

14kbckp.jpg

The dowel fits snug in the stock hole after you tap out the stud. Then slide over the drill guide (which snugly fits over the dowel and is spot faced, the ID is the proper one for the drill to be used) clamp it in place, remove the dowel and drill away.

Norval made those tools, I have one too and it works like a champ.
 
fastenal and NAPA have very good 64th drills in stock with 1/2 shanks.

If you were gonna tap anything 5/8-18 you would need a 37/64 drill.

;)
 
I did this for rear spindles and it is in my trailing arm thread in the rebuilding section. I installed ARP bolts with .625 kurl and the hole was 018 under. I called ARP on this they told me to go with 005 under but I'm glad I didn't. They would have been too loose. I pressed them in and they fit very good.
I'm going to do the front hubs next.
I set them up in a Bridgeport mill and used back gears to drill them after lining up the holes.
 
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