Wheel nuts should be expensive!

[Jersey Tom]

"Durability", eh? Interesting parameter that, can't find it in my material's handbook though?

Allright. Well if you're gonna keep bein a smartass I won't bother. But if you really don't understand durability as a design criterion I don't know what else to say anyway.

[xpensive]

Just take a look at the pic on the Brawn thread and tell me you believe those threads are made from steel?

[safeaschuck]

O.k. so we have 3 candidates for materials which have (almost certainly) been used, lets say in the last 10 years for formula 1 wheelnuts, they bein':

Ally
Steel
Ti

That something we can all agree on?

As far as I can see Ally still has the most doubt hanging over (including from me to a point) it so allow me to pose this-

If the nuts have this quick action anti undo mechanism as shown in some photo's surely they would need hardly any torque at all once in contact with the wheel? Provided the wheel was firmly pressed against the hub when the nut is fitted it only needs to be nipped up, the tension required against the thread to prevent loosening is unnecessary because it will not loosen until the centre pin of the release mechanism is depressed???
Then it's cornering forces we are worried about, which, taking into account the combined surface area on three/four threads on a nut that diameter would possibly allow the use of a high quality aluminium alloy with an anti gaul thread coating provided the wheel is very well braced against all other movement (which it will be) apart from londitudinally along the stub axle.

Then all 3 are possible? and indeed have been used?
As for Jordan using 1kg wheel nuts, good grief.

[xpensive]

Good analysis safechuck. Now, if you look again at that excellent pic on the Brawn-thread, that threaded shaft-stub is clearly an Al-alloy, while the teethed torque-transfer and tapered interface with the wheel, minimizes the need for preload.

As a concequence, shaft-stub, wheel and nut, all in Aluminium when Ti is too heavy.

[Jersey Tom]

xpensive - Which thread? The one that's 30 some pages? Do you have a link to which picture you specifically mean?

This one?



If so. That hub is not aluminum. Not a shred of a chance.

[n smikle]

That looks like steel.

I made a post two pages back. It was an interview from the Jordan Formula 1 team.

They said the biggest loads experienced by the Nut is from the Impact wrench. The Cornering forces is nothing for those threads.

Remember impact especially one that is repetive is the worst type of loading.

[xpensive]

According to scarbs, still on the Brawn GP thread, that hub is made from Titanium, which is also verified by the new picture on the same thread, displaying a very typical matt Ti-shine to itself.

Conclusively, Ti-male and Ti-female-thread makes sense, at least in the case of Brawn. Case closed.

But I would have gone for Al6082T6 anyway...

[humble sabot]

I think this thread has gone on as long as it has mostly because xpensive has a fetish for aluminium

[safeaschuck]

Wheel nuts should be expensive though, I almost changed my mind when I realised that ally was a potential material because with the safety mechanism deleted they would be quite cheap to make BUT, if you did that they would need torquing up, meaning yet another re-think and more than likely reverting to Ti to handle the increased impact stress's.
Basically the locking mechanism may negate the need for heavy torque and therefore Ti but what you save in materials and machining time on the nut itself being made is lost on the additional parts. It's got to be a 3 part design at least probably more like 4-6 pieces, some of which are probably Ti anyway (those being the locking pins/teeth/ring)

So to be light, strong, very quick to get on and off and with a high degree of safety a nut is going to cost enough to make most people curse and swear that teams are throwing away money, even if it is standardised across the whole grid.

For those weighing in on the side of simplification, even if it means backward steps I would only offer that the criteria above (light, strong etc.) I wouldn't consider as overly extravagant, just what people have come to expect from the sport, and indeed one of the largest differentiators between it and rival series, in fact a quick mental tot-up of circuits, chassis, engines, drivers, race formats etc. has me wondering: Is this sort of technology now F1's only unique selling point?

[xpensive]

Touche, humble.
But that might come from that in my world, I have to think twice before using 50 EUR/kg material, when 5 is an option.

[riff_raff]

Nice picture JT.

The stub axle and brake hat are likely Ti, in order to deal with the 1500degF plus heat from the CRC brake rotors. The centerlock nut however, is outboard of a forged magnesium wheel, so obviously temperature is not an issue.

An aluminum centerlock wheel nut is most definitely adequate. The race car I worked with was an IMSA GTP car that weighed 2000 lbs. and had a huge underwing. Much heavier than an F1 car, with more downforce, and with more rubber on the road. We used aluminum BBS centerlock nuts and never had a mechanical failure with one.

Maybe the F1 guys just like Titanium? Besides, they also use silicon nitride CV joint and wheel bearing components. And SiN is at least 10 times as expensive as Ti!

http://www.cerobear.de/index.php?id=37&L=1

[xpensive]

Finally, the words of a technical man with hands-on experience. Thanks, Terry.

Anyway, when you let engineers loose with an unlimited budget, you just never know they come up with, don't necessarily need to have a credible technical reason either.

Such as Magnesium-wheels, do they really use that? Saving what to a regular Al-alloy, 10lb all around?

[riff_raff]

xpensive,

to the best of my knowledge, the wheels are mag forgings.

http://www.bbs.com/en/motorsports/motor ... heels.html

A forged mag wheel would be 1/3 lighter than an aluminum wheel. And that's unsprung weight.

[xpensive]

Right, when density of Mg is 65% of Al's, which saves what, 10 lb all around? At a ridicilous cost when I'm sure teams throw them away after each race, no?

[humble sabot]

10 lbs on unsprung rotating mass is worth (without actually doing any math) at least 50 anywhere else.