//<86TA>\\

iTrader: (14)

As most as you know, a lot of BMW wheels, stock and aftermarket, use the 5x120mm (4.72") bolt pattern, and our GM vehicles use the 5x120.65 (4.75) pattern. The use of wheels with the BMW bolt pattern on vehicles with the GM pattern is quite common, and like many other things, there are people on both sides with strong opinions as to whether this is a safe practice or not.

I have found it very hard to find proper wheels to fit my 3rd gen without using the wrong pattern, or using large bolt on adapters, of which i am not a fan. I have found may different BMW wheels that i really like, at the right price, but the whole idea of using the "wrong" bolt pattern on my car, and the possible results are just not acceptable to me. While i have never personally seen a car loose a wheel because of this small difference is PCD (Pitch Circle Pattern, aka bolt pattern), i have heard many horror stories and seen many threads/pictures over the interweb of this possibility.

I had been looking for new wheels for my 92 since last summer, and while i want to use wide 18" wheels front and rear, my only real options were pricy 3pc wheels, or custom 2 and 3 piece forged wheels, and honestly i did not want to spend 3k on wheels for a car that i will be driving almost everyday, 9 months out of the year. I found a few options that look good and were in a much better price range, under 1500, but they always had the wrong bolt pattern, wether it be 5x120, or 5x4.5".

One night, by dumb luck i stumbled on APEX wheels, specifically the ARC-8 mesh wheel. Light weight, rotary forged barrel, an offset that is favorable for a 3rd gen (at least on the back) good looking and in the price range that i wanted. Yet they are only available in the 5x120 pattern. I decided to say screw it and bought a set through a GP on Bimmerfourms. Ended up with a great price, just over 1k for 4 18x10.5 wheels shipped to my door.

Here they are with my new brake setup


This began my quest to "correct" the wheels to the proper bolt pattern. Seriously, its only .65 mm, each stud is only .325mm off, so i figured this had to be possible by just re-cutting the 60 degree taper seat in the wheel in the proper location. I would have to cut the seat a hair deeper to remove the entire old seat and make a new seat for the lugs. Since its such a small difference, it seemed like a good idea, and totally in the realm of possibility.

I searched the interweb for literally weeks, over a month really, various sites, boards, ect trying to find somebody else who had done this, i found nothing, and no useful info. I looked for wheel companies to do this work for me, but i was told it was not possible, and i would have to have the lug holes machined out and have steel slugs pressed into the wheels with the new pattern. It would work, its apparently common, but it can get expensive with shipping since nobody locally to me can do it.

I was about to saw screw it again, and just bolt the damn things on and go, admit defeat, and move on. But by dumb luck i stumbled on automotive head valve seat cutting tools on ebay, and they are available in pretty much any size imaginable and, more importantly, are available in a 60 degree cutting angle. This opened the possiblily of doing this work myself, so i ordered one.



So with that out of the way, i needed a way to pilot the cutter in the lug hole. I ordered some basic drill pilots from Mcmastercarr, threaded externally to 1/2-20 since i have axles with threaded studs available to use. They have a close enough ID as the pilot of the valve seat cutter, so i though i had it done. Parts arrived and i find the drill guides are left hand threaded, and are not available in right hand thread. Back to the drawing board. I was going to head over to a machine shop and have them make me something when i made another accidental discovery. The pilot of the valve seat cutter is .297", which is pretty much 19/64. With dumb luck on my side as usual, i found that 6AN plumbing fittings have that EXACT ID on the flare side, amazing coincidence! So all i had to do was stop by the speed shop and buy a 6ANx1/2-20 powersteering adapter fitting, and once i drilled the 1/2-20 side out since it was a little smaller, i had a cheap, perfect drill guide.

valve cutter and guide



So finally, the leg work was done and i could attempt to convert the wheels.

The plan, use a axle shaft i recently picked up off TGO as my work stand, threaded in 4 of the studs, and my guide into the 5th hole. Added the hub-centric ring to match the wheels and i was ready to go.




the c-clamp is to keep the drill bit pilot from spinning.

Due to a 5 picture limit, this will be
Continued.....in a couple minutes.........

//<86TA>\\

iTrader: (14)

The entire setup, excuse the mess, its been a long winter....


ok, ready to start, and either trash a wheel, or achieve greatness.

I placed the wheel on the axle, located by the hub ring, lightly and evenly tightened 4 of the lug nuts to just hold the wheel from rotating, and began.

I cut the first seat by hand, used a ratchet, and some wd40 to keep the aluminum chips from sticking and clogging up the cutter head. Took me 30 minutes to cut one seat, thats nuts, i have no patience for that, so i did what everybody does in that situation, POWER TOOLS!

against my better judgment, i grabbed my cordless drill, chucked the bit in and continued the job, drilling very slowly, and keeping everything lubed.


this worked very well, better than expected. took about 15 seconds to re-drill the seats, and probably 6 minutes each time to remove all the lug nuts, clean the chips up and move to the next seat, bolt i back down ect. After the first seat was drilled, that lug would locate the wheel by itself and the other studs were just needed to keep the wheel sitting flat on the hub, after 2 were done, i was in business.

drill baby drill


the seat is smooth as glass, the discoloration is wd40/chips, and crap.. It all wipes off. Honestly, that picture may have been taken before i finished cutting, i dont remember.

clean up detail


1 wheel done,


15 more holes to go.....

continued.....

//<86TA>\\

iTrader: (14)

here is a lug nut, just tightened to where it contacts the wheel, you can see the gap between the lug and the seat because of the difference in PCD. This gives you a better perspective of how large the difference is. Its more than most people think i believe. I would seem to me that once the lug bent to fit the taper, the nut would be seating on a slight angle, so the surface area of the taper of the nut vs the wheel would not be correct, resulting on very little contact area between the two. Possibly the reason some people mention the nuts not staying tight.



here is the pilot in the lug hole, you can see that its more toward the outside of the wheel.



cutter sitting on the guide



once hole cut already, locating the wheel for the second


finished product



All 4 wheels finished in a little over 2 hours of work. I can order tires now!

Over all, not terribly hard really, however, having the threaded axles made life a lot easier. I would have had to have a press in stud machined into a guide if i didn't have these. It would still work but would have added some cost.

the valve cutter, 6AN fitting and drill bit cost me just under 80 bux. Worth every penny to no longer have that though in the back of my mind of a failure. The hub thickness of the wheel is the same as it was when i started, so no loss of strength in the wheel, and honestly, since the 60 degree tapered seat is wider now since the cutter blended the taper to the flush top of the hub where the original didnt, if anything they are stronger since the lugs seat more.

Its amazing what can be done for a couple bux with a little backyard, ingenuity. Maybe a small project for some of you guys to try sometime.

-Phil

InfernalVortex

iTrader: (4)

I commend you for your unwillingness to bolt the wrong bolt pattern to our hubs! It's a dilemma I've had to contend with also. This is an interesting solution, gotta be better than just bolting them on as is.

91 1LE

iTrader: (1)

My wheels will be here tomorrow. You going to be in AZ anytime soon? lol. I have the same axle lying around (as they didn't fit my posi without serious machining) so I thank you greatly for this idea I am going to use. .325mm doesn't sound like much but after seeing your pic with the lug installed, I would not want to run my wheels that way. I have too much money in the car to chance it to something stupid. I have those same brakes and had the same problems finding wheels that would fit. I have C6 wheels with spacers now but they didn't look right to me. I bought a set of 18" staggered Miro 111's with BMW 5 series offsets and will soon be modifying them. Thanks again for the ingenuity.

FSTFBDY

iTrader: (33)

Very nice work.

87350IROC

iTrader: (2)

Very impressive. Good job making it work.

Now what are you thoughts on converting the bolt pattern of the car instead?

Lets just say one was getting new aluminum front hubs anyway. Easy to convert there. And it seems like with a hub centric rear axle, you could easily redrill and tap the axle flanges.

//<86TA>\\

iTrader: (14)

If using a bmw wheel .was in the plan, I would have had the.front hubs made with both patterns, the redrilled the axles myself, but unfortunatly it did not work out that way since I also had problems with different wheels and a companies before I ended up with these wheels. I also do not know if a 120 bolt pattern with 1/2 studs would fit rotors with gm's bolt pattern. Mine are snug and I don't know if they have enough play for the smaller pattern. With 12mm studs, they would work fine.

87350IROC

iTrader: (2)

I hear ya. Its amazing how hard it is to buy wheels. Another option to think about for others.

//<86TA>\\

iTrader: (14)

An update, i finally got the car out and the wheels are awesome, no vibrations or any craziness. Pics will come this weekend hopefully

87350IROC

iTrader: (2)

In case anyone is wondering why go though the trouble of doing it right.

Lost a wheel on the freeway!

//<86TA>\\

iTrader: (14)

the price of everything i purchased to do this modification is still cheaper than replacing a wheel and wheel studs after a failure, tons less than replacing/repairing a car, and infinitely less than the cost of your or someones life.

Think about it

Twin_Turbo

iTrader: (25)

Who says he didn't seriously overtorque those studs, or someone else did? Also sounds like he's not using a hubcentric ring either.

I have been running BMW wheels with hubcentric spacers for years and years, I never had a problem. I have run these things hard, flat out on the German Autobahn every now and then, not a problem.

87350IROC

iTrader: (2)

All possibilities. But the wrong bolt circle is just going to make any situation worse, including proper torque. When you tighten the lug nut it is forced into the seat of the wheel by the tightening torque of the wrench. If the bolt circle is not correct, the lug nut will still go into the seat, but will have to "bend" the wheel stud to get there. Fasteners are not generally designed to take bending moments. In fact that is generally a big no-no in the engineering world. You are compromising the strength of the stud by introducing bending and tensile loads.

Twin, at the end of the day, you typically have very well thought out and executed cars. Based on that I am actually pretty surprised you are running BMW wheels, however I am sure you have thought about it extensively.

The problem is, most of the time on this forum its the blind leading the blind. I just want to give those folks something to think about.

Twin_Turbo

iTrader: (25)

The reason is availability. If I want correcrt pcd wheels I have to order in the Us, adding shipping tsxes and so on runs up the bill quick. Bimmer wheels are easy to get here.

87350IROC

iTrader: (2)

I believe it.

z 28 jari

iTrader: (1)

I have had also running 5x120 bolt pattern wheels at my Camaro cince 2000,only hub centric rings at them.Now with my current BBS wheels nuts like this:
http://www.ebay.co.uk/itm/PCD-WOBBLY...item4398456360

paul_huryk

Car looks great in person - love the 295s you have all the way round - lots of grip!!!

87350IROC

iTrader: (2)

Got any pictures of these? Sounds interesting.

//<86TA>\\

iTrader: (14)

http://www.youtube.com/watch?v=NVXljH8ms4s

thats a wobble bolt, but the idea is the same

87350IROC

iTrader: (2)

Well that is a pretty cool product. You would absolutely need a really good hub centric fit with those though since the lugs wouldn't be locating the wheel.

//<86TA>\\

iTrader: (14)

yup, thats why i opted to not use them, that and they dont make open ended ones

watajob

iTrader: (29)

Those "wobble" lug nuts just made my day! I never knew such a thing existed. I've been looking at these, ( http://4wheelonline.com/American_Rac....136096.613789 ), in an 18x9/120 and didn't know how to safely/economically pull this off. But, now I do! Thanks a bunch! BTW, you can get them on this side of the pond and, presumably, avoid international shipping hassles, ( http://www.tulipcitywheels.com/tcwst..._detail&p=1730 ).

87350IROC

iTrader: (2)

Just be aware, you MUST use hub centric wheels with the wobble nuts.

lowbird

I did'nt know they were even off i was thinking 120 is 120. I ran some bmw 19s for a long time. Never seen a problem with them. Thanks for the info . I will do this on my next wheels

watajob

iTrader: (29)

I'm gonna' do custom machined aluminum hub rings.

rayjay

I have a line on wheels for a 2011 Camaro, which have a 5x120 bolt pattern. Since this set-up will require spacers, and rather than use "wobbly" nuts or try to modify the wheels or hubs, has anyone purchased and used a set of spacer/adapters that bolt to a 5x120.65 hub and allow a wheel with a 5x120 to be bolted to it.

rj

87350IROC

iTrader: (2)

Yup. This the best way to do it if you are using adapters anyway. There are a few places that built custom adapters. I can personally recommend Motorsport Tech, but I am sure there are lots of other places that also do a good job.

rayjay

Thank you for such a quick answer, and for Motorsport Tech. I'll look into the adapter as it would seem to be the best way to go.

rj

rlewi771

axles with threaded holes for screw in studs......is that an aftermarket piece like moser or the equivalent, or is that something I could pull at the junkyard?

//<86TA>\\

iTrader: (14)

aftermarket only

DBLTKE

iTrader: (1)

Why isn't this a stickey yet?

akanitro

iTrader: (2)

Looks like I have a solution to fitment. Now just to find the cross lace GTA style wheels in 18 or 19".

Buloushie

iTrader: (-1)

Could the original poster please post the size of the cutter he used please. I'm going to be doing this soon and need to get the parts

//<86TA>\\

iTrader: (14)

1" 60degree

Buloushie

iTrader: (-1)

Thanks I saw the 60degree part just not the 1 inch

rgauder

iTrader: (1)

Could you please post the pictures again? This thread should be stickied.

jmd

iTrader: (4)

Well, that's coming soon.

https://www.thirdgen.org/forums/whee...crosslace.html

RT66ProTouring

iTrader: (2)

Reviving an old thread,
I used a similar procedure, but turned down a wheel stud from my differential upgrade project.



Note: What appears to be marks or scrapes on the wheel are actually only a reflection.

Cutting down the seat about 2.5mm did the trick.



The next pic may be a little hard to see, but the bottom lug nut was from a shallower cut and has marks on one side because the seat wasn't cut down enough. The top lug nut seated evenly all the way around when torqued to 100 ft-lbs (that's all the torque I could get with the axle and wheel mounted in the vice).

//<86TA>\\

iTrader: (14)

Good job!

91LsRs

hey what’s up. Back to the thread in 2022 again haha. So I read about this bmw on 3rd Gen setup but I’m curious. Does the hub bore matter? What if I were to get a 72.5 or a 74.1? I know our cars diameter is 70.3 I believe but what bmw wheel hub bore should I get? Thanks!

//<86TA>\\

iTrader: (14)

Suprised to see this one dug up again.

Doesn't make a huge difference, they make hubcentric rings to convert either one.