Mini Cooper Wheel Fitment (Stud Bolt Issue)

[qube 3570]

Came across an annoying issue recently thought I'd ask if anyone knows more about it.

Basically I got some wheels 4x100 to fit onto my Mini Cooper.

Later I found out that the bolt holes on the mags itself are only M12 and the mini uses M14x1.25 bolts so the bolt doesnt even fit through the hole.

option 1: get a machine shop to drill out 16 holes bigger to fit the m14 bolts (will it be perfectly centered if done so? worrying..)

option 2: bolt to bullet stud and nut conversion? Do they even have bullets that go from m14 down to m12??

What a pain in the a**.. why do they make wheels/cars with different sized bolts? as if having different PCD is not annoying enough as it is...

[aja540i 1906]

Any half decent machine shop should be able to drill the holes out perfectly, you would need to be happy that it won't compromise tbe strength of the wheels doing so.

[M3AN 4016]

#2 is the only viable option for the reasons you mention about #1.

Apparently a common problem, but also a common fix: https://www.outmotoring.com/mini-cooper/mini-cooper-M14_stud-conversion-kit.html

[qube 3570]

have seen this already thanks dave.. but for its over $200.. for a problem that shouldnt exist in the first place..

[M3AN 4016]

Okay Bill.

 

[qube 3570]

I have looked at so many wheels and not once had a problem with bolt hole sizes before..

Since I encountered this problem I have looked high and low but no spec sheet specifies a wheels' bolt hole size anywhere..

[M3AN 4016]

3 minutes ago, qube said:

I have looked at so many wheels and not once had a problem with bolt hole sizes before..

Since I encountered this problem I have looked high and low but no spec sheet specifies a wheels' bolt hole size anywhere..

I also assumed they were all the same and most seem to be 12mm which is obviously enough for most applications. Why BMW/MINI went for 14mm is beyond me. Any normal person could make this grievous error I'm sure. 

I'd still rather spend the $ on the studs than a machine shop.

 

[Herbmiester 923]

4 hours ago, 3pedals said:

Modern well engineered cars have wheel bolts for good reasons  and if you are concerned about saving nanoseconds in wheel changes you simply install a locating dowel. 

Curious as to what those reason are?

[KwS 2425]

7 hours ago, 3pedals said:

Modern well engineered cars have wheel bolts

Still yet to come across any Japanese cars with bolts, so not all "Modern well engineered cars" have them. Or are you just showing your ignorant bias and meaning European cars?

[kiwi535 538]

it doesnt matter if its a bolt or a stud does it?.All i know is if i google "mitsubishi pajero wheel specs it tells me it has m12 x 1.5 

If i google toyota landcruiser 200 series it tells me it has M14 x1.5 so the information is readily available but wether that information always goes with the wheel is another matter.

[KwS 2425]

Please explain it to us.

[M3AN 4016]

No, come on guys, do the mechanical engineering analysis 101, duh!

Anybody making even a casual scientific observation (or having a rational state of mind) would realise that in real-world applications it DOESN'T MAKE A F'ING DIFFERENCE.

Sigh.

 

[Gaz 1061]

What year mini do you have? Likey reason is that the early ones, R56 etc, were a Rover design so probably used different wheel bolt sizes. I suspect the newer Fxx Minis have the same as BMW. 

[qube 3570]

2008 R56. 

You may find it interesting to know that some BMW's also use the "odd" m14x1.25 bolts. Such as the new 2 series.

 

[M3_Power 636]

On 2/8/2018 at 10:39 AM, 3pedals said:

Modern well engineered cars have wheel bolts for good reasons  and if you are concerned about saving nanoseconds in wheel changes you simply install a locating dowel. 

 

On 2/8/2018 at 9:50 PM, 3pedals said:

Kelvin , all we can conclude from that is the Japanese don't engineer their wheel / hub connections as well as the Europeans. Do the mechanical engineering analysis 101 and you should be able to work out why it is a superior system. 

Hmmmm I don’t have an engineering degree but I am good enough with physics to know this can’t be true.

Nano second wheel change arguments aside, and ignoring wear and tear of stud or bolt, with appropriate material properties and thread pitch you can yield the same clamping force, sheer force and yield strength in both stud and bolt fastening methodology but you have the following mechanical advantages with a stud and lug\nut set up.

- consistency of tightening torque as the amount of thread engaged on a stud and lug nut is the same and not dependent on how many threads are picked up in the hub (more torque the more threads/friction or more bolt stretch you introduce - if any)

- safer and easier to inspect stud and lug\nut wear over bolt and hub wear.

- single vertical force acting on a stud and nut during the tightening phase vs two forces being acted upon on a bolt through stretch and twist in the tightening phase leading to a more accurate and even clamping between the two mating surfaces (think cylinder heads).

but apart from that I agree that the M14 to M12 stud kits are a bad idea vs enlarging holes in the wheel.

But give me centre lock anytime over everything else because “race car” lol!!   : )

Edited March 18, 2018 by M3_Power

[E30 325i Rag-Top 2956]

Centre locks FTW!

You just need the roof racks as well to carry the 10 foot long torque wrench required to tighten the bloody things up correctly, and be either strong or fat enough to exert enough grunt on the end of it!!

[gjm 3258]

14mm vs 12mm is a decision taken at BMW.

It started with the E53 X5. The MINI change came about during the move from the R50/3 to the R56, although some R50/3 cars also got 14mm bolts. The taper in the rim and on the bolt is the same regardless of 12mm or 14mm, so re-drilling is a practical solution.

[qube 3570]

Certainly there were a few mixed opinions and I have seen plenty of those on overseas forums running m14 to m12 bullet studs but if I were to do it I would have gone with drilling bigger holes. Anyway I have decided against it and have since sold the said wheels.

[Herbmiester 923]

All pretty much irrelevant for a street car.

[Herbmiester 923]

To expand on this then if Nissan sees fit to use studs rather than bolts on its GTR (Just one example of a performance car using studs) then I would say there is probably very little if any reason to worry. What is more important is the design of the hub the diameter of the bolts/studs etc..  Of the pointless arguments on this forum over the years bolts vs studs could be the winner.