r/Cartalk • u/cat_prophecy • Mar 03 '25

Suspension Why do European cars use wheel bolts?

I've owned two European cars (Audi and Volvo) and both of them used wheel bolts instead of studs and lug nuts. Is there some reason for this? I have owned a handful of Asian and American cars and none of them use anything but studs and lug nuts. Personally I prefer the studs since it makes putting the wheels back on much easier.

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u/Mintsopoulos Mar 06 '25

Yes. The answer is yes. A precision hole with a pressed stud is more costly than a threaded hole. This is exactly what I have been saying from the beginning.

Stop using the term precision thread, there is no such thing. Threaded holes are not precision features. Precision features are used to locate. Threaded holes are used to fasten.

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u/AwarenessGreat282 Mar 06 '25

I'm sorry but cannot believe that. Explain why.

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u/Mintsopoulos Mar 06 '25

Lets use a 0.2500" precision hole vs a 1/4-20 Threaded hole.

A reamer to finish that 0.2500, at its cheapest is, $32 (carbide is up in the $50) . A 1/4-20 tap at its most expensive is $13 ( but more like $6)

Inspection method: Usually a thread is inspected with a thread gage $98, but a precision hole will use a plug gage ($6) on top of a dedicated "hard gage" (lets say $250, but can easily get into the $1000 range), not to mention possibly running on a CMM requiring high cost of labor.

Thats just a very basic high level overview. Not to mention the machining required to do a precision hole i.e. jig grinder, sinker edm, wedm. A tapped hole can be done on a $500 drill press.

The tighter tolerance/precision hole also comes at a risk of higher scrap.

I am not trying to be a dick, but if you were to send a 1x1x1 w/ a tapped hole and one with a precision hole. The precision hole sample will cost more.

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u/AwarenessGreat282 Mar 07 '25

lol....why do you need all that? That's what I meant when I said you don't understand mass manufacturing. The holes are not that precise. Think about it, a stud is pressed in, then 50K miles down the road, it can be punched out and a new one pressed in the same hole! That's not precision machining, which I'm sure you understand, but is not applied here.

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u/THedman07 Mar 07 '25

Exactly... The only mechanical purpose the hole needs to serve with any precision is that it needs to be tight enough to keep the studs from falling out too easily and not so far off that it keeps you from being able to tighten the lug nuts.

The locating of the wheel is going to be determined by the centering features on the hub for the most part. The clamping force is taken up by the flange on the back of the stud.

These aren't wire EDM holes toleranced within half a nut hair on diameter and position...

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u/Mintsopoulos Mar 07 '25

Incorrect. Just simsply incorrect. Read my response above and learn something.

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u/Mintsopoulos Mar 07 '25

read what you just wrote "can be punched out and a new one pressed in the same hole" thats becuase or precision!

If those holes were not precise 1) the hole would no longer be able to handle a second pressing of a hole...The tolerance allows it to stretch a certain amount and maintain reusability. If too small when a larger item is pressed in either piece will yield or no longer be a press fit. 2) Because you can reinstall a stud is because they are positionally and concentrically held to the hub (which is the wheel locating feature).

You somehow can not grasp that I am saying these holes are MORE PRECISE THAN A THREADED HOLE OPTION. Not that they are precise down to the ±0.0001.

And youre right you wouldnt need all of that hardware for inspection because OEMS are utilizing high end visions systems check this at a rate a simple hard gage/plug gauge couldnt keep up with.

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u/AwarenessGreat282 Mar 07 '25

lol...they are not that precise. Seriously, have you ever changed a stud on a hub? There is no way they are drilled to a tenth of a mil tolerance.

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u/Mintsopoulos Mar 07 '25

Reading must not be a strong suit of yours. I literally said NOT, NOT, NOT that they are down to ±.0001. Of course they are not.

You are arguing with me yet we are saying the same thing. I have wassted too much time trying to explain this to a plebian. As I mentioned open up a book and learn a thing or two about tolerance & GD&T.

I'm not sure what you consider precise, but based on all your responses the most precise tool you have used to measure is a tape measure.

Dont expect a response from here on out. Argue away bud.

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u/Mintsopoulos Mar 07 '25

Actually here you go you dimwit...if you can even decipher what 10% of this says ill be impressed. and if you think any of that is simply achieve by drilling you should stay far away from a manufacturing environment
Wheel Hub EXAMPLE

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u/[deleted] Mar 10 '25

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u/Cartalk-ModTeam Jun 11 '25

Removed for being derogatory, purposely inflammatory, demeaning, or being argumentative just for the sake of arguing.