Legal wheel spacers?

[Forg]

Some of the Mercedes-Benz performance models have them OEM.

Volvo also ADR’d them for fitment of some of the optional wheels to their RWD models in the 80’s & 90’s

 

[Forg]

Completely agree but you have to give them some hope, who knows, sometimes if you find the right engineer who sees a "grey" area they might sneak it through...

That’s not really all that useful though; if most engineers interpret the rules one way, and you get an engineer that interprets it the other way, you’re opening yourself to your certificate being made null & void when the engineer becomes un-certified.

 

[Skylarking]

Wheel studs are held in tension by the wheel itself sitting between the hub and torqued up stud nuts. Thus the stud’s job is purely to hold the wheel hard up against the hub face itself. Sliding force across the hub face itself, and thus a cross the studs themselves will cause them to fail over time.

What stops the wheel from sliding along the hub face is the hub flange which engages with the big hole in the middle of the wheel itself. Surprisingly the flange at only 5 or so mm but is able to take all the sliding forces and make the whole shebang safe.

All,the spacers I’ve seen push the wheel away from the hub face so the the hub flange no longer locates the wheel and thus the studs take foxes they weren’t designed to handle. Rather unsafe.

So @panhead, @vc commodore or @Forg, since you’ve seen MB, Porche or Volvo OEM provided wheel spaces, do these spacers engage with the hub flange in the same way as a normal wheel would? Do these OEM spacers also provide another wheel mating face with flange that the wheel then locates on? How thin/thick is the whole EOM spacer?

I suspect that the OEM spacers must be made of a quality steel as I suspect aluminium alloy would be to soft. Do you guys have any pictures of these OEM spacers?

Just curious as to how they look and mount

 

[Sandman]

I've just bought some bolt on spacers (pictured) for my drift car actually to help with steer wheel fitment. As far as I see it as long as they are still hub centric and is a bolt on type not a slip on type there is no real disadvantage, other than the force travelling through more components making a slightly higher force on the base of the studs. But being hub centric this still should not be a big issue anyway. I wouldn't use them on the street for legality reasons of course, but on the track my mates have used (and abused) these for a few years with no issues. Never seen OEM ones so can't help on that side of things.

 

[panhead]

Wheel studs are held in tension by the wheel itself sitting between the hub and torqued up stud nuts. Thus the stud’s job is purely to hold the wheel hard up against the hub face itself. Sliding force across the hub face itself, and thus a cross the studs themselves will cause them to fail over time.

What stops the wheel from sliding along the hub face is the hub flange which engages with the big hole in the middle of the wheel itself. Surprisingly the flange at only 5 or so mm but is able to take all the sliding forces and make the whole shebang safe.

All,the spacers I’ve seen push the wheel away from the hub face so the the hub flange no longer locates the wheel and thus the studs take foxes they weren’t designed to handle. Rather unsafe.

So @panhead, @vc commodore or @Forg, since you’ve seen MB, Porche or Volvo OEM provided wheel spaces, do these spacers engage with the hub flange in the same way as a normal wheel would? Do these OEM spacers also provide another wheel mating face with flange that the wheel then locates on? How thin/thick is the whole EOM spacer?

I suspect that the OEM spacers must be made of a quality steel as I suspect aluminium alloy would be to soft. Do you guys have any pictures of these OEM spacers?

Just curious as to how they look and mount

Hub centric spacers sit on the hub and have their own flange for the rim to sit on.

There is one big difference between a Merc and a Holden, the Mercs don't have wheel studs, they use bolts that go through the rim and screw into the hub and one advantage to this is that you can purchase the wheel bolts at any length which means you can easily tailor a set to suit the extra length of the spacers and you can just swap back to the OEM bolts if you remove the spacers.

With a Commodore you may need to have the studs replaced with longer ones to suit the extra thickness of the spacer.

The hub centric spacers all work on the same principal and sit on the hub not the studs or bolts.

There are different types of hub centric spacers including the bolt on ones like Sandman has shown.

These are my 10mm aluminum hub centric spacers. You can see the spacer slips over the hub flange and the rim sits on the spacer flange.​

These are the type of bolts Mercedes use instead of studs, in fact these are a set I bought that are 10mm longer than the OEM wheel bolts to make up for the 10mm spacer.

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[Skylarking]

Thanks for those pic and for clarifying my terminology.

From an engineering perspective, whether studs or bolts are used to hold a wheel on a hub, it makes no difference. Stud/bolt tensile streangth is what is relevant. So as long as the length of the stud/bolt is increased to cater for the extra thickness of the hub centric spacer, there should be no engineering issue as I’d expect.

Why then is it seemingly so difficult/expensive for an authorised certification engineer to approve their use and why must it be done on a per vehicle basis? Even more frustrating when one considers the fact our regulators are seemingly aligning our rules to accept European certification (and TUV certified hub centric spacers are cheap).

So it’s exactly what I thoughts where OEM hub centric spacers are legal when fitted by the manufacture but the exact same product used on another car is not legal due to our stupid overly bureaucratic bureaucracy

 

[Forg]

Why then is it seemingly so difficult/expensive for an authorised certification engineer to approve their use and why must it be done on a per vehicle basis?

I imagine it doesn't have to be done per vehicle, you could probably get the spacer certified for a model of wheel & model of car via whatever the process is for type certification … ie. the way an importer gets an entire model certified. But that'll be even more time-consuming.

The reason for cost even if one-off has a few components. I think there's a fee to lodge the certificate, there's a crapload of insurance the engineers have to carry, and the engineers also get forced into spending a whole bunch of time sifting through the myriad of ongoing niggling/irrelevant changes the employees of the rule-making authorities spew-out in order to justify their jobs - so when you get something engineered, you have to pay for that engineer's 'wage' for a portion of that sifting. There's apparently a few hour's worth of paperwork just to engineer one Thing.

 

[Immortality]

Thanks for those pic and for clarifying my terminology.

From an engineering perspective, whether studs or bolts are used to hold a wheel on a hub, it makes no difference. Stud/bolt tensile streangth is what is relevant. So as long as the length of the stud/bolt is increased to cater for the extra thickness of the hub centric spacer, there should be no engineering issue as I’d expect.

Why then is it seemingly so difficult/expensive for an authorised certification engineer to approve their use and why must it be done on a per vehicle basis? Even more frustrating when one considers the fact our regulators are seemingly aligning our rules to accept European certification (and TUV certified hub centric spacers are cheap).



So it’s exactly what I thoughts where OEM hub centric spacers are legal when fitted by the manufacture but the exact same product used on another car is not legal due to our stupid overly bureaucratic bureaucracy

I would imagine that fitting wheel spacers changes the load on suspension components and particularly the wheel bearings/hub just like fitting much larger/wider tyres especially if they end up sticking out a lot further. Manufacturers spend countless hours designing and testing before it is ever released to market. Joe blogs who takes off his 8" wide rims and fits 10" wide rims with a 2" spacer because the new rims offset is wrong really has no idea what that does to the loading on his suspension components.

In the case of the OP, fitting a small spacer would probably make **** all difference but if he was allowed to what is going to stop someone else putting a 2" spacer into something that will make a big difference? At the end of the day the law should be written to cover the majority of situations and generally covers everything to stop the idiot from hurting himself (and more importantly) other road users.

At least here in NZ we have the LVVTA who can certify vehicle modifications from mild to wild and they have very specific rules and guidelines to what can and can't be done and what's better is they work with the authorities so there is no questions.

Edit: also, changing the vehicles wheel track widths can alter the handling of a car.

So as we learned from the Brembo brake upgrade thread/saga, what seems like a simple mod can have unintended consequences, especially in modern cars where the electronic systems are finely calibrated to tyre/wheel size, brakes etc with regard to modern traction control, ABS systems and what ever other myriad of systems moderns cars have these days.

 

[panhead]

Thanks for those pic and for clarifying my terminology.

From an engineering perspective, whether studs or bolts are used to hold a wheel on a hub, it makes no difference. Stud/bolt tensile streangth is what is relevant. So as long as the length of the stud/bolt is increased to cater for the extra thickness of the hub centric spacer, there should be no engineering issue as I’d expect.

Why then is it seemingly so difficult/expensive for an authorised certification engineer to approve their use and why must it be done on a per vehicle basis? Even more frustrating when one considers the fact our regulators are seemingly aligning our rules to accept European certification (and TUV certified hub centric spacers are cheap).

So it’s exactly what I thoughts where OEM hub centric spacers are legal when fitted by the manufacture but the exact same product used on another car is not legal due to our stupid overly bureaucratic bureaucracy

To put it in basic terms the Australian government works on the premise that we need to be protected from ourselves and therefore much of the legislation passed in Australia is aimed at the lowest common denominator and everyone else has to suffer because of it.

Spacers as already addressed by Forg and immortality have an impact on many areas of the vehicle's handling, suspension and structural integrity all of which then impact on safety and therefore are not something for the backyard enthusiast.

What I don't understand is they are allowed in other countries that have strong vehicle safety standards and they are common on race tracks around the world where vehicle safety is considered of paramount importance and therefore why can't the thinner spacers be engineered here for use on road going cars?

As Forg has pointed out it costs to attain engineer certification but I've had a few vehicles engineered for engine, brake and suspension upgrades and I see the certification cost as part of the ongoings for the mods and if spacers where okayed under engineering supervision a standard would be implemented and the costs reduced.





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[vc commodore]

Wheel studs are held in tension by the wheel itself sitting between the hub and torqued up stud nuts. Thus the stud’s job is purely to hold the wheel hard up against the hub face itself. Sliding force across the hub face itself, and thus a cross the studs themselves will cause them to fail over time.

What stops the wheel from sliding along the hub face is the hub flange which engages with the big hole in the middle of the wheel itself. Surprisingly the flange at only 5 or so mm but is able to take all the sliding forces and make the whole shebang safe.

All,the spacers I’ve seen push the wheel away from the hub face so the the hub flange no longer locates the wheel and thus the studs take foxes they weren’t designed to handle. Rather unsafe.

So @panhead, @vc commodore or @Forg, since you’ve seen MB, Porche or Volvo OEM provided wheel spaces, do these spacers engage with the hub flange in the same way as a normal wheel would? Do these OEM spacers also provide another wheel mating face with flange that the wheel then locates on? How thin/thick is the whole EOM spacer?

I suspect that the OEM spacers must be made of a quality steel as I suspect aluminium alloy would be to soft. Do you guys have any pictures of these OEM spacers?

Just curious as to how they look and mount

I don't have a picture of a Porsche spacer, and it has been years since I saw one, however from memory, they are alinimum and a style, which slide over the wheel studs on the rear and locate the rim...The 80's and 90 era 911's had them