I've noticed that the latest versions of some cars have five wheel bolts/studs compared with the previous four.
Is it for styling, or functional, purposes?
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Is this a continuation of the "leather or fabric" thread, to enable you to choose four or five bolt wheels on the V40 without committing a social faux pas? ;-)
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>> Is this a continuation of the "leather or fabric" thread, to enable you to choose
>> four or five bolt wheels on the V40 without committing a social faux pas? ;-)
>>
:-D
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Five has been pretty well universal for ten years or more, hasn't it? Certainly on the medium and large cars I've looked at. Last four-bolt wheels I had were on my 1.4 Astra in 1993. I presume it's to do with the greater weight and power of modern cars - and yes, even the torque at the driving wheels - increasing the load on wheel mountings.
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And that must be why a 2CV has three studs!
Mon Dieu, zat rice pudding has a skin...
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Car weights are probably 60% higher than in the 1980s. Braking is probably the biggest stressor of the wheel attachment system. Assuming similar friction between tyre and road the forces will be up 60% too.
I have noticed that the bolts or studs are much bigger now too than they were in the old days.
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>> I have noticed that the bolts or studs are much bigger now too than they
>> were in the old days.
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Does that mean that the hexagon size is bigger and that if I get a new car I'll have to buy a bigger socket?
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>> Does that mean that the hexagon size is bigger and that if I get a
>> new car I'll have to buy a bigger socket?
In the case of the handfull of different Vauxhalls I#ve had since 1986, it's the other way around.
The hex size of the bolt used to be 19mm, now it's 17mm, but the thread size remains the same.
Lucky I had a star wheelbrace as 3 of my bolts on my old Mk3 Cavalier were 17mm, and the locking wheel bolt (donated from an earlier Vauxhall I once owned) was 19mm.
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>> Last four-bolt wheels I had were on
>> my 1.4 Astra in 1993.
My 2003 Focus only has four studs.
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>> Five has been pretty well universal for ten years or more, hasn't it? Certainly on
>> the medium and large cars I've looked at. Last four-bolt wheels I had were on
>> my 1.4 Astra in 1993. I presume it's to do with the greater weight and
>> power of modern cars - and yes, even the torque at the driving wheels -
>> increasing the load on wheel mountings.
>>
The old Saab 9000 only had 4 (can't remember if they were bolts or studs), but they were pretty heavy and some of them had high torque loadings at the wheels. The 9-5 went to 5 bolts, but they are slimmer than the 4 bolt/stud fixing on the 9000.
I can't really imagine that it's fashion, must be a mechanical reason.
But whoever heard of ANY road car shearing the wheel bolts? Is this just a case of "bolts & braces)?
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Oh dear, decisions, decisions, four big bolts or five smaller ones. Or is it studs? Heaven forbid someone has a pickup or van with six. :-)
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They will have had loads of parts left over from the 5 stud top end model and thrown them into this "new style motor" to look different.
Had a astra belmont on a H plate 1991 it's rear brakes as standard were from the Nova and it's drums there were getting shut of quanties of parts.
There is more 5 stud wheels now so you can find alloys to go with it.
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All but accidental loads are applied to the wheel via the friction between the tyre and the road. Therefore, the loads at ground level are proprtional to the vehicle's mass.
The torque at the wheels which can be produced by the vehicle isn't usually the limiting factor defining wheel bolt loading if the vehicle is capable of breaking traction.
The geometry; namely the ratio between the rolling radius of the wheel and the pitch radius of the bolts defines how the loads at ground level are magnified at the hub.
It's usual to consider an accidental load as a proof loading event - typically a kerbing test. Here, the loads are proportional to the square root of the product of the vehicle's mass and the stiffness of the suspension in the loading direction.
In design, it's usual to perform the calculations for routine loadings assuming that the joint has one fastener less than the nominal number.
Interestingly, having a large number of wheel fasteners with taper seats becomes a serious tolerancing problem, because you know that unless the bolts and holes ALL line up perfectly some of the bolts will end up carrying a bending load as well as apurely axial load - this is very bad for fatigue, and is one of the reasons why the old British system of holding commercial vehicle wheels on was so bad for wheel security.
As I've mentioned before, the interface between the wheel and hub is really a clutch - the drive and braking torques are transmitted via friction - the bolts should not bear any lateral loads. This is why it's a bad idea to copperslip this interface. The bolts should only be subjected to axial loads.
In summary, it's vehicle mass and geometry which are the decisive factors.
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>> I can't really imagine that it's fashion, must be a mechanical reason.
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Perhaps. At one time we had 2x Astras in our household. Both from early 2003, both Elegance spec models. One was a 1.6 petrol with 100bhp, the other a 2.0 diesel with 100 bhp. Both had the same wheel design, except that the petrol had 4 studs, the diesel 5.
It made no sense to me at all. The only difference in spec (apart from the engine) was that the diesel also came with traction control. Maybe something indirectly to do with that for some arcane reason? Otherwise, I couldn't see why they should be different at all.
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More noseweight, possibly different brakes, certainly different gearbox.
Which means you pick different drive shafts and hence hubs from the "already being made" parts bin.
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Probably right Zero, now I remember it, the gear shift was rod actuated in the 1.6 and cable in the 2.0 diesel. Possibly had discs on the back of the diesel too, its front end was certainly heavier.
Last edited by: oilburner on Fri 21 Sep 12 at 12:14
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>> Perhaps. At one time we had 2x Astras in our household. Both from early 2003,
>> both Elegance spec models. One was a 1.6 petrol with 100bhp, the other a 2.0
>> diesel with 100 bhp. Both had the same wheel design, except that the petrol had
>> 4 studs, the diesel 5.
>>
When my dreadful 1996 Vectra 1.8GLS (4 studs) was changed for my departing colleague's returned 1996 Vectra 2.0CDX I noticed that it had 5 studs.
IIRC in that particular model the 1.6/1.8 had 14" wheels and smaller disks than the 2.0/V6 models which had 15" or 16" wheels and larger disks. I think the 1997 Astra shared many components with this Vectra too? IIRC they brought out a tax-dodger 1.8 SRi which had 16" wheels with 4 studs because I remember making fun if a colleague who'd specced one (OK so I once succumbed to the company-car hierarchy, I am both repentant and reformed now).
it deeply saddens me that I know this.....
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I saw lots of recent 4-bolt cars this morning ~ a 2008 Mitsibushi Lancer, a 2012 Nissan Note, and enough Ford Fiestas to cobble dogs with.
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>>to cobble dogs with
Ooh, a new phrase (to me). Nice. Thank you L'es.
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>> Thank you L'es.
>>
No probs. wiki.answers.com/Q/Where_does_cobble_dogs_come_from
tinyurl.com/btxroaw
Last edited by: L'escargot on Fri 21 Sep 12 at 14:19
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>> I saw lots of recent 4-bolt cars this morning ~ a 2008 Mitsibushi Lancer,
The lancer has nuts, not bolts.
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Which is the most secure? - Screwing a nut onto a welded stud, or screwing a bolt into a threaded hole?
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Studs aren't usually welded. Usually they are pressed in from the other side of the hub, or screwed in from the face side. Not sure if that makes any difference.
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I suggest we compare the number of each type (bolt and stud) in which correctly fastened wheels separate from the hub and then decide it makes no practical difference.
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The Volvo 240 had 5 studs from new, 1974 I think, and probably its predecessor the 140.
LandRover 5 studs from 1948.
My 1947 Triumph Roadster had 5 studs.
The old system of bolting on wheels was to use flat nuts and split conical washers. This presumably avoided the problem mentioned by Number-cruncher of precise alignment to prevent bending forces on the studs.
I have a 1947 ex-army trailer with 5 studs using this system. The wheels were standard VW of the period, and have abnormally large holes to go with the large washers.
My 1949 Ferguson tractor has 8 studs on the rear and 6 on the front.
So I don't think it's anything new, nor to do with engine power.
Of course there is one obvious factor - the size of the wheel. Old cars had very large wheels - 16" was commonplace, 19 or 20 before the war.. Then wheels got smaller, 15, 14, 13 ", and now they have gone up again with low profile tyres.
Last edited by: Cliff Pope on Fri 21 Sep 12 at 20:28
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>>The old system of bolting on wheels was to use flat nuts and split conical washers. This presumably avoided the problem mentioned by Number-cruncher of precise alignment to prevent bending forces on the studs.
That's the very system which was problematic Cliff. As the split conical washers were a good fit on the stud, the bolt / hole alignment had to be spot on to avoid bending loads.
The system which replaced it on trucks was the spigot system where the bore of the wheel knave was made a good fit against a shoulder or spigot on the hub. The wheel stud then passed through a generous clearance hole in the wheel, and the nut had a hardened flat washer (whaich was retained with the nut). This design very clearly seperated the role of the hub geometry in locating the wheel, and the role of the wheel bolt to provide only an axial clamping force.
For those who remember Leyland trucks, the changeover happened in the early 1980's - those with Ergomatic cabs had the old system, and those with T45 cabs had spigot mounted wheels. Replacing broken studs was common work on the older type of truck as they got some age andmileage on them, while the spigot mounted wheels were much more robust.
The spigot system is a more logical high performance bolted joint design, whereas that used on most cars is quite a confused design in terms of function. In fairness, it would be difficult to reliably clamp a thin steel wheel without the pressed in taper feature, and that largely explains the continued use of the design.
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My Jowett has 5 studs but the 1930s models had 6. Good quality nuts in those days, and with a chamfer on both sides so you didn't need to fit them one way. Useful on a dark rainy night perhaps ?
My neighbour's Vintage and 1930s Rolls Royces ( Rolls Rice ? ) had 6 nuts as well. I noticed, on the Rollers, that a lot of the nuts on the engine were chamfered off. Presumably to prevent that knuckle barking, flesh ripping pain when the spanner slips.
Our 10/11 reg Fiestas have only 4. I did a puncture today on one.....well, a kerbing and I didn't do it, the mobile tyre man came and I watched. One simply can't be doing with dirty hands.
Ted
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>> I did a puncture today on one.....well, a kerbing and I didn't do it, the mobile tyre man came and I watched.
>> One simply can't be doing with dirty hands.
I had to change a tri-axle trailer tyre the other week (OSF) for the same reason, took a chunk out of the sidewall coming around the Park Plaza hotel on my way to Westminster Bridge. That wheel was a 5-stud.
I have a pair of decent rigger gloves for that kind of job :)
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I have rigger gloves in the bus as well but I don't want to get them dirty. Actually, I would have done it if the car had had a spare, rather than a pot of goo and a pump.
The only way would have been to remove the wheel and take it down to National but that would have meant leaving it jacked up on MY trolley jack in a Salford street...no way !
I discharged a can of tyreweld into in the hope it might get me going enough to take in but that only found the hidden split. Anyway, there was a nice cafe opposite with cherry scones to die for !
Ted
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Maybe they should just have one large nut in the middle, and a rawhide mallet?
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Five wheel bolts/studs or four? - Mike H
