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In the past small/medium cars had four for each wheel and large cars had five(I know there were some with three and some six) but now there are large cars with four and small with five-WHY?
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Cars have been getting gradually heavier since the 1960's when monocoque contruction became universal - more weight means more strain/stress during cornering, etc so increasing the number of bolts/studs shares those strains/stresses out more.
In addition modern cars have larger diameter brakes/wheels than older ones which makes it easier to fit more studs/bolts in.
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Don't be fooled by some wheel trims which give the appearance of five bolts, but which cover a four-bolt hub!
I must say that I very much bemoan the modern trend to fit bolts instead of studs. Trying to get a large wheel with a minimal centring bore to stay put on the hub whilst fitting the bolts can be a very irritating process :-( Some manufacturers do provide a removable locating stud for this purpose, but that's the first thing to go 'walkies' just when you need it....
The move to bolts I presume stems from the increasing use of disc brakes (even at the rear), with the discs being retained by the wheel bolts - rather than by being bolted to the hub.
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Off at a bit of a tanngent on the 4/5 studs bolts.
Outside the house a handicapped chap's Scenic had a puncture and on calling motability helpline he was told it would be 90mins - 2 hours for a van.
With the help of a neighbour the whelle was changed -getting the alloy off was a small problem. The bigger problem was that the spare was steel and the normal wheel was an alloy - there were no other bolts in the car so we used the "alloy bolts".
Surely there should have been steel bolts and coppergrease on the hubs - After all it was a motabilty car! I told him to srive slowly and get the alloy fixed ASAP.
Not a good show for motability or Renault.
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My Xantia, and the BX16v before it had alloy wheels and a steel spare. The same bolts were used if the spare had to be fitted. The spare wheels had bosses welded on to the bolt holes to bring their thickness up to the same as the alloys.
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For over 20 years the Vauxhalls, and now Subaru, use the same bolts/nuts for alloy OE fitment and the steel spare.
The problem can arise on cars with OE steel wheels where the bolts/nuts may not be suitable for aftermarket alloy wheels.
M-B are the only manufacturer I've heard of that need different bolts/studs and they include an appropriate set with the steel spare.
Coppergrease ?? Never used it nor had problems getting wheels off.
Edited by Ruperts Trooper on 31/12/2007 at 11:25
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>>Coppergrease ?? Never used it nor had problems getting wheels off.<<
I've seen an alloy wheel fitted to a Megane so corroded on that the wheel had to be destroyed to get it off. The car was about 2 years old.
I managed to catch the Xantia just in time when I bought it before the wheels bonded to the hub. The car was ex lease and I knew that the level of service it would have received would not have included anti-sieze compound on the hubs.
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"My Xantia, had alloy wheels and a steel spare. The same bolts were used if the spare had to be fitted."
"M-B are the only manufacturer I've heard of that need different bolts/studs and they include an appropriate set with the steel spare."
Wife's Xantia (W reg) has different bolts which are contained in a "Citroen" box with the alloy lock nut socket thing.
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PhilW,
You've got me worried, now.
Mine's a T reg. I'll have to refresh my memory and have a look at the spare.
My Citroen box just has the alloy lock nut socket thing and the plastic false nut puller.
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Just had a look, and checked manual. Same bolts, bosses on spare to suit.
Brrr, its cold out there!
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I'm glad i'm not the only one to get coppergrease on the wheel hub mating surfaces smartish.
Know what you mean about lease cars and servicing, we are moving a lot of 6 to 12 month old vx's at the mo and some of the drivers door hinges are almost siezed solid with rust dust coming out of the hinges.
I know these extended service intervals have some good points but good servicing includes a lot more than changing engine oil.
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Extending service intervals from 12 months to 24 months isn't a good idea but has absolutely no effect on vehicles "6-12 months old".
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mjm,
I think the spare bolts are somewhat shorter than the alloy ones - may be different if alloys are different style? Ours are like the ones on this Xantia
www.gtsbillingshurstcars.co.uk/web%20site/gts/wpe3...g
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Same ones, PhilW. Standard fit on Exclusives, I think. The mounting holes in the steel spare are "built up" and shaped to take the standard bolt.
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"The mounting holes in the steel spare are "built up" and shaped to take the standard bolt. "
Maybe I'd better have another look at ours then!
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Coppergrease ?? Never used it nor had problems getting wheels off.
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Then you are a lucky fellow !
Previous detailed, researched advice said do not use copper or any grease on the threads. They are designed to be "dry".
Having experience serious problems getting wheels off, especially alloys, I use copper grease on the mating surfaces especially the hub.
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>>Previous detailed, researched advice said do not use copper or any grease on the threads. They are designed to be "dry".<<
They may well be. In my opinion there is so much over-engineering in the wheel nut/bolt area of normal cars that a smear of anti-sieze on hubs and threads does more good than harm.
I have never worried unduely about torqueing the bolts up, either. I just do them up "tight" bearing in mind that they have to be undone again.
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Using copper grease between the wheel and hub came up in a recent thread, when I suggested it shouldn't be used as friction between these surfaces is required to prevent the wheel moving arond, and straining the fixings. Number Cruncher replied with his usual aplomb to show that it's marginal. That is it's OK on low power applications, but could be dodgy on higher power/exuberant starts/heavy braking.
www.honestjohn.co.uk/forum/post/index.htm?t=58292&...e
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I read N/C's post and would not disagree with his calculations.
There is a difference between grease and anti-sieze compounds. A/S compounds are formulated to prevent corrosion and siezure, hence the copper content. They have the appearance of grease but not the lubricity. I think there is a tendency to call them copper grease because of their appearance, not their function.
I don't know what friction modifier N/C used in his calculation.
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The idea (and therefore the use of ) copper grease is that the copper acts as the anti seize compound, carried in grease for ease of application. Under high temperature applications (its best used for) the grease melts, runs away but leaves the copper behind to act as the anti seize compound.
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>>I don't know what friction modifier N/C used in his calculation.
mjm - the purpose of the calc was to estimate what co-efficient of friction ight be required to prevent any slippage.
The answer to the calc came out as something like 0.08, for the wheel size, and bolt types that I had considered.
A dry contact will easily exceed 0.08, and so there's no danger of slipage when dry - but a well greased one could be in that range of friction co-efficents - which is why I said it was marginal.
In another recent thread, I've estimated what margin there is between the stress in a torqued wheel bolt, and the yield stress for the bolt material - for a grade 10.9 bolt, approximately 60% of yield stressis used during torquing. If you grease the threads, this stress goes up, if you guess and overtorque the bolts, the stress in the bolts goes up. If you grease and guess, I would say it's likely that you damage the bolts. As steel is quite aforgiving material, and bolt grades represent minimum yield stresses, and there's still quite a bit of plastic strain left beyond yield, people tend to get away with it.
Number_Cruncher
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