i've noticed over the last few years that more and more cars are being fitted with 5 stud wheels.
why is this?
is it something to do with wheel security or weight loading?
i've got a four stud mondeo and wheels from other ford cars will fit.
is it the same with other makers? will vw golf wheels fit a passat? i even saw a newish vw polo with 5 studs today so it can't be to do with weight carrying, can it?
OR
is it a cunning plan by the car makers to do away with aftermarket alloy wheel companies?
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It's mainly a marketing ploy - wheel fixings are generally now visible and 5 gives perceived superiority over 4. With a target market of poorly educated customers, car makers go to great ends to produce visible "features" - lighting in various guises is a particular favourite. BMW door handles, indicator repeaters on mirrors are typical examples. The visual impact and "must have" reaction to such irrelevancies is high.
It's also easier to make alloy wheels using more fixings as this wheel material has poor strength compared with its steel counterpart and benefits from lower stress per fixing.
659.
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rubbish
its to give the 5th man a job
;-)
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If it's just for show why does my pick up have 6 studs and my truck wheels 8 or 10?
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obviously its to keep wheel nut manufacturers in business
i mean look at a lot of the cars young kids drive,they should run on 4 wheel nuts and studs but lots of them think only 3 is needed after the lockers are wanged
so its overkill by manufacturers
innit
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Citroen AX only had 3 wheel nuts too innit
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And there was me thinking it was all to do with superior engineering.
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>>its to give the 5th man a job
I thought his job (used to be) holding the horses... ;-)
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I seriously doubt it's solely for appearance's sake. Middling cars are about 50% heavier and more powerful than they were even 20 years ago, and often the range includes proportionately more powerful variants. Even though the extra weight is on the spigot (in most cases - our aged Land Rover doesn't have spigoted wheels but does have 5 rather thick studs, and nothing on that car is there to improve its looks!) the studs/bolts are still at risk from extra torque.
Or maybe I'm just one of those poorly educated customers ;-)
Now if you were looking for an explanation for the predominance of alloy wheels...
Edited by Manatee on 06/09/2009 at 16:30
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I would have expected the introduction of alloys, larger wheels (16-19 inch) and more powerful cars, to be accompanied by 5 stud wheels..
With 4 studs all the forces are transmitted through only those 4 studs and the stresses will be much higher than with 5 studs. I would expect 5 studs to reduce the stresses on the wheel considerably and prevent cracking, warping and any heat related failures. It ain't for fun that lorry wheels have so many studs.
I would expect very high performance cars with very large rims and a bit of weight to have more than 5 if space permits without weakening the wheel.
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Can't imagine anything much more powerful than an F1 car - and they only have one big central 'stud'! There must be more to it than power alone.
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F1 cars weigh a lot less than a Citroen AX but the wheels come adrift a lot more often. Just ask Fernando Alonso :-)
Edited by old crocks on 06/09/2009 at 17:53
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>>all the forces are transmitted through only those 4 studs...
If the design works properly, most of the forces between the hub and wheel won't go anywhere near the studs, regardless of whether there are 4 or 5 of them.
The bolts work rather like the springs which clamp together the clutch - the load goes through the clutch, not through the springs.
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>>The bolts work rather like the springs which clamp together the clutch - the load goes through the clutch, not through the springs.
Good explanation - I abandoned trying to think of a non-laborious way of saying that.
Interesting that hubs/drums usually have completely flat faces, and I have never seen any admonition against greasing them - on cars with alloy wheels I use some copper grease between the wheel and the hub to stop it sticking on as they often do.
The power and weight considerations are still relevant though - more clamping force is required than used to be the case.
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>>I have never seen any admonition against greasing them
After doing a fairly simple calc in an old thread, I found that slippage across a greased hub/wheel interface is possible under hard braking - which would result in the bolts bearing a load for which they were not designed, and, so, I cautioned against such greasing.
However, I agree, it's odd that there isn't usually any firm official guidance.
The wheel to hub bolted joint on motor cars is in most respects grossly over specified, and it usually copes well with malpractice during wheel mounting, and wheel loss is quite rare.
The same happy situation is not found with heavy vehicles, where a much more rigorous procedure must be followed if wheel loss is to be avoided. [As most of these heavy vehicle wheel loss incidents are the result of studs snapping, the plastic pointers are next to useless!]
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Don't worry N_C ... the copper in the copper grease will actually accelerate corrosion between the steel brake parts and the alloy wheels so the studs are safe.
............. ahem
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The forces on a wheel are not just turning moments. The car corners, is subject to lateral loads etc.. The studs take many more forces than you think as does the surface of the Alloy wheel....This would probably cause some designs to crack. In addition metals flex and are, is subject to expansion and contraction. Impacts can put unusual loads on all parts of the wheel.
Formula one cars are concerned with overall weight and so the wheels are lighter, or a different alloy to road wheels and fastened with a centre hub to facilitate speed of wheel changes. These central hubs will also have a continuous contact area around the wheel for even loads distribution. The also won't stay on the car for 100,000 miles or more!
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>>The car corners, is subject to lateral loads etc.
Although it's more difficult to believe, even lateral loads aren't borne fully by the studs - only about 10 - 15% of the load is seen by a well designed and installed stud. You should be surprised by this, because unless you've studied how bolted joints actually work**, you'll think it's untrue.
>>The studs take many more forces than you think...
You don't know how many forces I've been thinking about! I wrote about the clutch action, because it's the easiest for people not involved in bolted joint design to visulaise.
** Most people don't know how bolts work, not many mechanics actually know how bolts work even though they spend all day working with them. As engineering is such a broad church, it's also possible to be an engineer without really getting to grips with the subject.
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It's to make the number of studs a metric quantity.
;-)
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...It's to make the number of studs a metric quantity....
The CC3 has four plain studs (bolts?) and one locking one per wheel.
Total per car: 16 plain studs and four locking studs.
Looks more like hexadecimal to me, or whatever you call it. :)
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The CC3 has four plain studs (bolts?) and one locking one per wheel. Total per car: 16 plain studs and four locking studs.
You should also find the locking wheel nuts are not at the same torque as the standard studs otherwise the only way the locking nut is coming off is with a drill.
Volvo recommend the standard wheel nut is torqued to 140Nm. Torque the locking wheel nut to that and the adaptor will chew up when trying to remove the locking nut.
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You should also find the locking wheel nuts are not at the same torque as the standard studs otherwise the only way the locking nut is coming off is with a drill.
I've tightened locking wheelnuts/studs on alloy wheels to the same torque as that recommended for the standard nuts/studs (85Nm) on my cars since 1986 without a problem.
Check here for the recommended torque for your car.
www.etyres.co.uk/car-makers
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OK, maybe that was an over generalisation as some cars require less torque on the nuts than others. 85Nm is different to 140Nm to a locking wheel nut key.
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