///// Aftermarket wheel Fitment issue .... stud / bolt holes not big enough /////

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Hi All,

Just when I thought I got it all figured out a snafu reared it head up at the last minute

I received my stud bolts (60 degree taper cones to help center the wheels) and wanted to make sure I had enough length to go through the new wheels into the hubs of my car.

Much to my disappointment the stud bolts don't even go through the holes in the wheels !!

Ugh .... I was planning on getting the new tires and wheels put on my car tomorrow because OI am close to the wear bars now.

What can be done to fix that ? (I did check to make sure I had the correct wheel bolt by comparing it to one on the car now ... they are correct and the one I took off the car won't fit through the wheel bolt hole of the aftermarket wheel.

I did get centering rings for the aftermarket wheel so that will be right ....

I just have to get the bolt holes enlarged to allow the bolt studs to fit through .... It's pretty close (I was hoping to sand it out BUT I know it has to be fairly precise to it all goes together properly).

I have a drill press at the house if that helps.....I thought about setting stuff up so a drill bit goes through snugly, mounting tightly, THEN getting a bigger drill bit to enlarge the hole .... will that be good enough or is there abetter way to do it? Open to ideas .....I'd feel best if a machine shop could do it BUT I livei n a small town so that is a big ask....

What is the diameter of a stock vw wheel bolt stud opening so I can make sure I have the correct bit size if I can do it myself BUT the table on the drill press is really small so I guess I'd have to put plywood on it to support the wheel etc...

Thanks in advance for any and all help / suggestions

Andrew
 

Poor King

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May 20, 2020
Location
NY
TDI
'91 Jetta, '91 GTI, '04 Touareg
Take it to the wheel shop because after they redrill it they will most likely add little inserts to prevent the holes to crack. Plus it will be done straight and correctly because they have the equipment to do this.
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
I've been googling online about enlarging bolt holes on wheels ....

Some say :

1) No problem drill away.

2) Some say ream only no drilling OR Drill close to size then ream

3) Others say Don't even think about it .... not safe

After finding the wheels I wanted (took over 9 months of on / off searching to find the wheels in the make , model and size) ), getting the hub centric spacers figured out / found , now the final hurdle seems to be the M12 the wheels are drilled for VS the M14 they need to be to work with pur Jetta Lug bolts.... so close yet so far..... I had no idea before now that this would even be an issue (maybe it'll save some others from this same situation if they stumble across this thread).

Anyways, I had looked for a machine shop to do the work but the only one reasonably close by is on vacation for a week or so ( I waited this long so what's another week ? .... Of course I'll at some point have to park the car since the tires are getting close to the wear bars ( I keep saying that BUT there still is a little margin left .... it's surprising how long they last ( so far 71K on the tires with probably 1/2 mm left on the fronts to the wear bars .... I may be able to rotate to prolong it a bit more).

The lugbolts for many aftermarket wheels (including these) run 60 degree tapers I think to presumably help center the wheels ( this cross references my thread about needing hub centering rings if the bolts could do the same ?? I opted for the Hub centering rings too in the end).

My largest concern is not about the 2 MM or so the holes have to be enlarged BUT my brain cannot wrap itself around if cutting out the bottom of the hole somehow alters the geometry so that the taper of the 12 MM shoulders would not somehow be working properly with the 14 MM bolt shoulders even tho I think both angles is 60 degrees.

I was half tempted to buy some playdoh and make an impression of a 12 mm cone type lugbolt and somehow see if the 14 MM lugbolt taper works with it (fits in the same mold) despite the bottom of the hole being drilled out to fit the larger bolt I need.

I'm sure this can be figued out mathematically (or by common sense?) but I have to admit it is beyond me to say definately ..... Plus I would hate to screw up a good wheel if I am wrong).

My gut says 60 degrees is 60 degrees if it is on a 12 MM bolt or a 14 MM bolt BUT .....

Anyways, researching more still .

Andrew
 

Poor King

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May 20, 2020
Location
NY
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'91 Jetta, '91 GTI, '04 Touareg
Like you said, you waited 9months, now do it rite. What were you going to use for a drill anyways?

Most likely you won't get the enlargement absolutely/true with a regular drill and then will widen the holes further fixing the mistake. That's 20 holes that you would have to get perfect.
 

jmodge

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Jun 18, 2015
Location
Greenville, MI
TDI
2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
Just JB weld 12mm studs to your hubs, playdoh won’t hold
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Like you said, you waited 9months, now do it rite. What were you going to use for a drill anyways?

Most likely you won't get the enlargement absolutely/true with a regular drill and then will widen the holes further fixing the mistake. That's 20 holes that you would have to get perfect.
I researched a bit more ....

I think if I simply drilled the hole bigger , the taper will still be there BUT only a little less taper length (from top of taper to bottom of taper) since I would be enlarging the hole at the bottom where the taper starts for the wheel....

The amount that the taper is reduced I think can be calculated using trigonometry from back in the school days BUT I probably cannot figure it out now with my older brain!

Since I would have to enlarge the hole 2mm, I would effectively be removing 1 mm from each side of the centerpoint of the bolt (the radius) and in theory that could be used to calculate how far up the 60 degree taper I would be losing.

I cannot think if the length of taper would be more or less than 1 MM due to the 60 degree angle.

in either event it really is not alot BUT sometimes maybe the 1 MM extra is the difference between strong and not (like overboring an engine .... amounts are sometimes very small).

My thought as far as drilling (If I get beyond the structural strength thing) :

Set up the drill press and chuck a bit in it that perfectly fits the existing hole (snug)

Fasten the wheel firmly in that position.

Remove the small snug fitting bit and use the bit of the size I need the hole to be (just a hair bigger than the size of the bolt ... I may measure to see how the factory bolt fits in its hole but it is not a tapered cone like this).

Drill the hole.

Rinse and repeat 20 times.

At some point if this works, I'll have to do the same for the spare (but that runs a different bore so have to get a different hub centering adapter (same wheel brand and for the most part size but a different manufactured year so different centerbore ? (or maybe for a different car BUT still sadly 12 mm not the 14 mm we need).....

As far as accuracy ? The above should be fairly accurate .... any slop should be taken up by the centering ring and the cone on the lugbolts.

There was a guy on You tube simply using a hand drill and step bit and calling it good so I guess you get the full range of what people think is good enough / usable ( Obviously , made from the factory fit would be best BUT I have also heard of people filling the holes with weld and remachining everything.... that sounds good / better BUT the wheel is forged so unnecessary welding may screw things up strength wise unless stress relieved / heat treated ?

I am almost at the point of drilling thinking (hoping) it will be OK

Andrew
 

MukGyver

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Dec 11, 2020
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Sierra Ca
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2004 Jetta PD
It depends on how much you need to remove. If it is very small amount it could be done with a reamer. However a reamer that size will not follow the hole straight if it's poorly centered under a press and if not perpendicular. So a setup on a drill press is very "iffy" for that reason. The right way would be to do it on a mill like a manual Bridgeport mill. I would think a small town has a mill somewhere with a good ol boy who would do it for a case of heinekin.
However, if needing to be removed is only about .010" or less then you might be able to get away with a hand drill and reamer. Again it really depends on how much needs to be removed and how deep you're going too. It also depends on what the material is. I'm assuming its aluminum.
 

Andyinchville1

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Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Yes, the wheel is forged aluminum.

The man who runs a somewhat local machine shop got back from vacation and I spoke with him about enlarging the holes for me.

Amazingly one of the first things out of his mouth was why don't you take a drill and enlarge it... ha

I think in theory I could do it but it would take me a while to do 20 holes with super Precision plus I would have to buy the drill bits for my drill press since I don't have anything that big currently.

I'm probably going to pay him a visit tomorrow early ... he quoted me a price of probably less than $100 so I guess it sounds like about $5 a hole or less ... while he's on a roll I mean sneak in my other rooms because I got to have a spare after all and might as well make it a light one.

For ease of doing and savings of time I'll probably just go ahead and do that... because for me to have to order the drill bits (which is even more time and expense) and since I'm running on the wear bars anyway I figured I need to get the newer tires on sooner than later...

Andrew
 

Andyinchville1

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Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Update: dropped off all the wheels off at a machine shop and they should have everything drilled out for me in the morning.

I brought them a spare Avis wheel to measure the bolt opening and it's surprisingly loose tolerances.

I think a hole will end up being something like a 16 millimeter or so hole.

Once I get the wheels back I'm going to see how many threads protrudes out the back because I think the Hub area is sticker on the aftermarket wheel so I hope there's enough thread sticking through to properly bolted to the hub if not I guess yet another delay having to order longer studs but we'll see after tomorrow.
 

jmodge

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Joined
Jun 18, 2015
Location
Greenville, MI
TDI
2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
The holes can be loose as the Avis wheels are hub centric
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Update :

Got my 7 wheels drilled to enlarge the bolt holes back today (I'll have to ask him the bit size but he measured my spare Avus wheel for the bolt size and drilled to match that size).

Anyways , the total cost (and he had to buy the drill bit) was $120.

He said it was an easy job once he got the first hole started (He has a full machine shop with all the fancy stuff because he used to build race engines).

I would like to have seen him do it to watch and learn but I'm just happy it was done.

Hopefully tomorrow or Friday, I'll get the new tires mounted on the wheels and see how the car feels with lighter unsprung weight.

Hoping for a big difference in feel but I'm kinda doubtful BUT I just had to know/ see firsthand so we'll see shortly.

Andrew
 
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