TheSamba.com :: View topic - What size drill bit for 1/2 inch wheel studs?

Tue Jan 10, 2012 10:04 am

Anyone know what size drill bit you use for the Dorman 610-258 wheel stud that is commonly used on custom bolt patterns? The knurl is .536 diameter...

Tue Jan 10, 2012 10:37 am

Who's in Grant's Tomb?

1/2"?

Tue Jan 10, 2012 10:40 am

Quote: Who's in Grant's Tomb?

How much does a ton of air weigh?

Tue Jan 10, 2012 10:49 am

I'm not understanding the sarcasm :? - Is 1/2 drill bit the correct answer from someone that knows for sure or has a chart? These things use a specific size, for example I was able to find on a Mustang forum that a stud with a .619 knurl uses a 39/64 drill or reamer- but I couldn't find a listing for a .536...
So are you guys telling me that when they use that Dorman 610258 stud it's a straight 1/2 hole and not something like 31/64 or 33/64?

Tue Jan 10, 2012 10:59 am

In order to slide a 1/2 inch thread through a hole, it will have to be 1/2 inch. You can measure the thread and see if a 31/64 will work.

I used a completly different 1/2 inch thread stud on my '59 bus that required a 9/16 hole for the knurled end to fit.

Tue Jan 10, 2012 11:02 am

Sorry, I had too...the title said it all, "What size for a 1/2 inch"...it's kinda redundant and funny to me...Ok, I'm a jerk

The answer in close terms would be: .536 x 16 = 8.576
8.576 rounds up to 9,which would be ..............9/16", a hair over 1/2".

Tue Jan 10, 2012 11:07 am

I just got off the phone with Socal and he said the spec for the press interferance is a hole size 13 thousandths smaller than the knurl size, but his guy that would know the exact drill size they use wasn't there right now...The reason it has to be exact is too large a hole and the stud can spin and a slightly too small hole can/will crack the drum when it's pulled in- Don't ask me how I learned that the hard way a few years ago on an old Mopar changing from oddball 5on4 to 5on4.5 :roll:

Tue Jan 10, 2012 11:09 am

Longrifle wrote: Sorry, I had too...the title said it all, "What size for a 1/2 inch"...it's kinda redundant and funny to me...Ok, I'm a jerk

The answer in close terms would be: .536 x 16 = 8.576
8.576 rounds up to 9,which would be ..............9/16", a hair over 1/2".

Uhmmmm...

A 9/16 drill bit is 0.5625 inch. The knurled section on the stud is 0.536. If the hole is drilled to 9/16 inch, there would no longer be a interference fit to hold the stud in place.

Tue Jan 10, 2012 11:14 am

Quote: 13 thousandths smaller than the knurl size

0.536 - 0.013 = 0.523 inch diameter.

33/64 is 0.516 inch
67/128 is 0.5234 inch
34/64 is 0.531 inch

IMO, I would go with the 33/64.

Tue Jan 10, 2012 11:17 am

Directly from Dorman catalog for wheel studs....

Believe 0.013" is to small (try maybe .020).... Play with the numbers with a bit larger size... Also if there is doubt about amount of "bite" in knurl, spot weld head of stud to drum.

If you try to small a hole you will stress drum and since it is cast, you may crack it....

33/64" seems like a better number (0.516")...

Also you have to consider where the head of the stud lands inside drum... Is it flat, does it need to be reamed to a flat so head will seat properly...

Dale

Tue Jan 10, 2012 11:21 am

well, then.. .500 = 1/2" and the "closest match" for the common drill bit would be .536 = 9/16 approximately. Yes, it is a little oversized...unless you can find a 17/32 or 34/64 bit...that's about as close as you can get to .536" I think.

Would the 1/2" bit give you the necessary shoulder for the stud to fit tight? Or call the parts dept. or wherever you bought these parts for additional insight? Don't be afraid to ask for help.

Tue Jan 10, 2012 11:28 am

Longrifle wrote: well, then.. .500 = 1/2" and the "closest match" for the common drill bit would be .536 = 9/16 approximately. Yes, it is a little oversized...unless you can find a 17/32 or 34/64 bit...that's about as close as you can get to .536" I think.

Ummmm check you math...

Dale

Tue Jan 10, 2012 11:29 am

Thanks Dale, I missed that on Dormans website- and Joe I actually have 17/32 and 33/64 bits, used those odd sizes on other projects...It sounds like 33/64 falls right in the range that Dorman called for in their catalog....I'm getting deja-vu on this, I maybe used these same studs on that Mopar stuff approx 8 years ago, but I've lost brain cells since then :roll:

Tue Jan 10, 2012 11:33 am

http://bobmay.astronomy.net/misc/drillchart.htm

Tue Jan 10, 2012 11:36 am

EDIT : Damn I got to learn to type fast and spell check faster...

Good drill cross reference chart metric/inch ....

http://bobmay.astronomy.net/misc/drillchart.htm

Says a 33/64 is actually '.515625"" which put its in the "ball park" for a .536 knurl...

Dale

Tue Jan 10, 2012 11:38 am

ok, 33/64 = .515625........I've neglected to purchase that size bit

Tue Jan 10, 2012 11:41 am

Mal evolent wrote: http://bobmay.astronomy.net/misc/drillchart.htm

I have a similar chart laminated hanging in the shop that lists drill bit sizes for certain tap sizes (probably how I ended up with those odd size drill bits..) but wasn't sure if thread sizes and knurl sizes were similar animals....With all that info Dale found I'm fairly sure now 33/64 is the correct size..

Tue Jan 10, 2012 11:44 am

Longrifle wrote: ok, 33/64 = .5346........I've neglected to purchase that size bit

Some of these fractional sizes are hard to find unless you go to an industrial supply store or website like Graingers....

Tue Jan 10, 2012 11:55 am

Dale M. wrote: Directly from Dorman catalog for wheel studs....

Also you have to consider where the head of the stud lands inside drum... Is it flat, does it need to be reamed to a flat so head will seat properly...

Dale

Another thing I remember is that after the surface is flat, you are then supposed to chamfer the edge of the hole slightly so the stud seats flat without stressing the hole...The machine work on whoever built my buggy was so bad they machined flat spots on the back of the front drums for the studs without covering up the bearings at all and put it back together with the bearings full of steel shavings, first time we jacked a front wheel up my son called me over to hear the crunching noises when he spun the wheel :shock:

Tue Jan 10, 2012 12:05 pm

donbarnes wrote: Longrifle wrote: ok, 33/64 = .5346........I've neglected to purchase that size bit

Some of these fractional sizes are hard to find unless you go to an industrial supply store or website like Graingers....

Internet search.... between $6 and $12...

Dale