Does anyone have any general info on fasteners used on F1 cars? I am particularly interested in how the quick change nose operation goes. I think the Honda change was particularly slick. Any info would be great. Also, how do think they lock fasteners (or do they, based on Massa's spring accident). The FIC WRC guys must have that down to an art as well.

"The fasteners used on F1 cars" can mean all sorts of things, from high strength bolts to fast-pins to Dzus fasteners, which are quarter-turn, cam-lock fasteners. They use a hollow cylinder with a head that looks like a screw head (or sometimes a wing nut); the cylinder has two slots in it that engage a wire spring and snap into position. That holds the body panel in place, but still makes it easy to remove.

A typical Dzus fastener grip





A typical Dzus fastener spring.


This photo of a spring tension adjustment tool shows the basics of how the cylinder engages the spring.



As you would expect, there are many variations on the basic theme. Some grips are captive, others are loose; they can be made of plastic, aluminium or steel, depending on the application. There are also a number of sizes and shapes of backing plates for the springs.

In most cases, the fasteners are done or undone using a simple tool (see below) or a screw driver. There is even one version that is shaped like a wingnut.



Dzus fastener tool.



Oval, winged Dzus grip.

When you see a pit crew change a damaged nose section in seconds, they're using Dzus wrenches to turn the countersunk fastener grips, which are attached to the nose. It should be noted that the fasteners do not carry the entire aerodynamic downforce load -- the nose cone extends well onto the monocoque, which takes most of the strain.

In Felippe Massa's accident, a number of things went wrong. First, a bolt and/or nut must have vibrated loose. This would be a failure of the safety wire or lock-tite used on it; assuming anybody put some on the bolt in the first place. Second, when that fell apart, it freed the third spring -- which does not have a concentric damper -- allowing it to get loose and go bouncing around. One of the retainer and/or mounting fittings may also have broken in that incident. It's hard to tell from the fleeting glipses in the onboard camera footage. And I doubt Brawn Grand Prix is telling...

Good info GreyWolf74. I never knew what those were called. The cowling on my Honda CBR uses about 20 of them.



Visually, these are classics too.




I guess the guy’s last name (and hence fasteners) are pronounced like “Zeus”, an Ukranian American guy invented them.

http://www.qtrturn.com/history/wdbio.php
“So how does an aircraft fastener become world-renowned? Young guys returning from combat began building land-based fighters called hot rods. They'd experienced the virtues of the Dzus fastener during combat and deduced that it would offer the ultimate in utility and simplicity for souped-up street cars and all-out racing applications. You know the rest.”

http://www.americanheritage.com/articles/magazine/it/1997/2/1997_2_42.shtml
“In his book Carroll Smith says that “Dzuses tend to be easier to find, more forgiving of minor misalignment and more positive in their locking action” than other types of quarter-turn fasteners. This praise from a famous engineer would have gratified William Dzus.”

GreyWolf74 - 04 November 2009 01:23 AM

In Felippe Massa's accident, a number of things went wrong. First, a bolt and/or nut must have vibrated loose. This would be a failure of the safety wire or lock-tite used on it; assuming anybody put some on the bolt in the first place.

My guess, based on my own experience, is that Brawn used a 'jet nut' - a type of self locking nut with an extremely thin hex wall thickness and very light, much lighter than a nylock - that split on one of the flats and worked loose.

I saw this splitting happen a few times in IMSA and it usually wasn't a big deal, the nut would not work loose because the bolt sizes we used were a bit of overkill (think 24 hour races and Sebring); we weren't anywhere near as weight conscious as F1, and might have used a 3/8 (10mm) bolt where in F1 they might use a 7mm or even custom made 7.5mm to just barely meet the need.

wilmywood8455 - 04 November 2009 08:13 PM

GreyWolf74 - 04 November 2009 01:23 AM

In Felippe Massa's accident, a number of things went wrong. First, a bolt and/or nut must have vibrated loose. This would be a failure of the safety wire or lock-tite used on it; assuming anybody put some on the bolt in the first place.

My guess, based on my own experience, is that Brawn used a 'jet nut' - a type of self locking nut with an extremely thin hex wall thickness and very light, much lighter than a nylock - that split on one of the flats and worked loose.

I saw this splitting happen a few times in IMSA and it usually wasn't a big deal, the nut would not work loose because the bolt sizes we used were a bit of overkill (think 24 hour races and Sebring); we weren't anywhere near as weight conscious as F1, and might have used a 3/8 (10mm) bolt where in F1 they might use a 7mm or even custom made 7.5mm to just barely meet the need.

That's quite possible. Why anyone would skimp on the weight of a nut used in a high-stress application, I don't know, but that's racing for you -- save half a gram when you can.

For those wondering what the difference is, here are some pictures.



As you can see, a "jet nut" is a very thin-sided nut with a broader base to spread the load. It also offers considerable thread area (vertical height inside), which would help keep it tight and spread the load to a lot of threads. This would typically be used with a washer, or perhaps a lock washer, to keep it tight. If a jet nut was used on the Brawn, it may have split or vibrated loose, or probably one, followed by the other. Either way, the results were "not good."



These are "nyloc nuts." They look like ordinary nuts and are, perhaps, slightly taller. What they have inside one end is a blue nylon insert. When the nut is tightened, the threads on the bolt or stud cut into the nylon, which is flexible enough to withstand vibration. Thus, the nut is less likely to back off, which means you may not need a lock nut or a lock washer to keep it in place.

Signature:

If “Ignorance Is Bliss,” I’ve met some very happy people in my time.

This video shows the nose assembly replacement up close, and mentions "two captive bolts"; briefly showing the guy twist-tighten something. (at ~2:12)
http://www.youtube.com/watch?v=tzfRBVJrzzA

However – I’m fairly positive I’ve seen nose replacements where the nose was just pushed on, with no mechanical tightening at all.

Here you can see a Ferrari nose with 4 doweling set-pin connectors. I swag that there are captive bolts in the chassis receivers, and actuate under the heads of these set-pins. So you can just push the nose on to lock it, and have a simple recessed release push-pin in the chassis.



And similar for Redbull, which shows a flat match (i.e. no male/female connectivity between the carbon.)



(Also interesting here is the main upper suspension arms extending forward beyond the nose receiver into thin air. That geometry problem must have briefly beguiled Newey! Looks to be too flexy as it stands. The nose cone could serve as an “immovable” foundation for both bars to push against, but if that is the design, and the nose cone is ripped off … you couldn’t get the car back to the garage without total failure of the front suspension. Maybe they have that much trust in the security of the nose connectors…. Total wild speculation – and off topic to the nose connector question at hand.)

The only thing in the tech regs is the nose push-off test – talking about strength of the connection, with zero detail on what/how.