On my mountain bike(s) suspension I have titanium springs all round. Huge weight savings. I paid an extra $800 tacos to float like a butterfly and sting like a bee. However, many people feel (myself included) that the compliance/plushy factor is slightly lacking in Ti, and much more “feel” can be achieved by using steel – if you can handle the weight penalty.

I naturally assumed F1 cars categorically use titanium springs, but I’m looking at pics and I’m wondering if that is true. Maybe iron springs allow for more “mechanical grip”, and are worthy of the extra weight penalty? I believe most of the springs are along the centerline of the chassis.

Or is some other spring metal used?

(And as a subnote, how in the world could one of these come loose on Barrichello’s car without catastrophic suspension failure?)

I'm not sure what the springs are made of, but I can give you some further information on how that all works. If you refer to your third photo, you can see there is only one spring present, in the center. The individual wheel springs are actually torsion bars mounted vertically which rotate about the green area in the linkage at the center of the photo.

The spring in the center is part of the "third damper" assembly. The linkages are constructed such that the third spring/damper only comes into play when the travel of the entire axle is identical side to side, such as when travelling at high speed and the car is under heavy downforce load, or hitting bumps perpedicular to the direction of travel. This makes the handling of the car easier to tune due to minimizing the effect that the downforce has on how the individual corner springs and dampers extract mechanical grip from the tires. The front end of the car is set up similarly.

As to how this part fell out fo Barrichello's car without a complete failure, you can see that the car would still be suspended by the torsion bar spring effect on the individual corners. The car would have still been somewhat driveable, but quite a handful through high speed corners and likely would have been bottoming.

Great photo, ipso, thanks!

F1 teams use either Steel and Ti springs in both coil and torsion formats. McLaren have used hollow Ti coil springs for their 3rd spring for many years, the penalty for the lighter spring is it is physically larger than the steel spring and in F1 packaging counts for a lot. Coil springs as ‘ferrarifan’ pointed out are not commonly used, aside for the third spring, even then a stack of Belleville spring washers sometimes replace them.

The third spring has a few mm of free play such that is doesn’t add to the spring rate of the rear axle until several mm of ride height have changed, then it kicks in. If its missing the car would sag at high speed, this would make the car feel awful, but not make the rear end of the catastrophically collapse. On Barichellos car, the 3rd spring is fitted to simple telescopic assembly (as often its not a damper), a bolt on the rocker linkage worked loose and allowed the spring to rattle free.

for information on the most used spring in racing, even F1....

http://eibach.com/cgi-bin/htmlos.exe/0961.3.058495132200031723

***Though most spring companies keep their metal content mostly secret, most are a spring steel (treated steel) and the Rockwell number (measurement "return" after applying a major weight to the spring) is of the most concern as far as the spring maintaining it's spring rate over time.
The biggest problem in using alternate metals is the Rockwell number and whether the spring can maintain it consistency over it's lifetime...
Quite a few teams have gone to using torsion bars instead of regular springs (for the four regular springs).

ferrarifan54 - 06 October 2009 09:44 PM

I'm not sure what the springs are made of, but I can give you some further information on how that all works. If you refer to your third photo, you can see there is only one spring present, in the center. The individual wheel springs are actually torsion bars mounted vertically which rotate about the green area in the linkage at the center of the photo.

The spring in the center is part of the "third damper" assembly. The linkages are constructed such that the third spring/damper only comes into play when the travel of the entire axle is identical side to side, such as when travelling at high speed and the car is under heavy downforce load, or hitting bumps perpedicular to the direction of travel. This makes the handling of the car easier to tune due to minimizing the effect that the downforce has on how the individual corner springs and dampers extract mechanical grip from the tires. The front end of the car is set up similarly.

As to how this part fell out fo Barrichello's car without a complete failure, you can see that the car would still be suspended by the torsion bar spring effect on the individual corners. The car would have still been somewhat driveable, but quite a handful through high speed corners and likely would have been bottoming.

So the green thing is the center of the torsion bar lever. OK… Presumably a piece of metal (the part that twists) extends downward from the green center. I can see then how the two shocks support the spring-enabled levers.

Or are the fiberglass arms serving as the “torsion” springs relative to the levers? That wouldn’t be torsion though, I don’t think; that would be more like a leaf spring actuation. In any case, I wonder what % the fiberglass arms serve on overall spring rate.

Your explanation of the third spring is fascinating. Conceptually it makes perfect sense. I can see how the linkages (both wheels at the same time) bear evenly against the center spring (assuming the spring is being extended vs. compressed) but I don’t see (visually) how they are not affecting each other. I don’t see any differential type mechanism. I’m looking at a lever with a direct linkage to a bar with a linkage directly connected to the other lever – so not sure how the top of the third spring is affected – other than maybe being pushed away, and that center vertical bar has a hinge (fore/aft, pitch) as well as some kind of bearing at top for swivel (yaw).

I’m missing something I think – even though I’m looking right at it.

ipso - 07 October 2009 12:01 PM

[So the green thing is the center of the torsion bar lever. OK… Presumably a piece of metal (the part that twists) extends downward from the green center. I can see then how the two shocks support the spring-enabled levers.

Or are the fiberglass arms serving as the “torsion” springs relative to the levers? That wouldn’t be torsion though, I don’t think; that would be more like a leaf spring actuation. In any case, I wonder what % the fiberglass arms serve on overall spring rate.

Your explanation of the third spring is fascinating. Conceptually it makes perfect sense. I can see how the linkages (both wheels at the same time) bear evenly against the center spring (assuming the spring is being extended vs. compressed) but I don’t see (visually) how they are not affecting each other. I don’t see any differential type mechanism. I’m looking at a lever with a direct linkage to a bar with a linkage directly connected to the other lever – so not sure how the top of the third spring is affected – other than maybe being pushed away, and that center vertical bar has a hinge (fore/aft, pitch) as well as some kind of bearing at top for swivel (yaw).

I’m missing something I think – even though I’m looking right at it.

Again, this is all referring to the third photo. There are the two pushrods extending up from the torsion bar linkages up to the another linkage attached to the third spring. Call this the laterel linkage. If only one corner of the car goes up, it simply pivots the lateral linkage. If you look directly below the lateral linkage (think of below as though you are viewing the car directly from the side), you will see another bar bolted to the transmission that pivots fore/aft attached to the third spring linkage. Call this the longitudinal linkage. When both wheels move together, as when under high downforce, the lateral linkage remains perpendicualar to the third spring, and the top of the longitudinal linkage will move rearward, compressing the third spring.

The torsion bar pivot ratio is the length from the center of the torsion bar to the point where the carbon pushrod connects. And I'm trying to grasp this as I explain it to you, but I'm also missing something. The way I'm looking at it (and after I sketched it out), if the car rolls as in a corner, the suspension does not appear as though it is fully independent.

I just did some hand waving of the motions and might have had a light bulb as to how brilliant this may be. As the outside corner is compressed, it will draw the third spring lateral linkage on that side rearward. This must then push the outer side of the lateral linkage forward. Adding cornering load to the outside tire then also adds a similar load to the inside tire to maintain traction. Undoubtedly, the elctronic differential controls are going through all sorts of trickery to manage what this load-sharing is doing.

Anybody feel free to correct my assumptions on this. And by the way, I just found this forum last night. Thanks so much for the intellectual technical forum conversation!

Article explaining more about about waht is called inerter,j damper,jounce or heave spring.

It also shows what may be a more common transverse rather than longitudinal location. If I interpret the drawing right the whole assembly essentially "floats" between the suspension pieces which explains why it's control is only in the vertical plane when both sides compress it.

http://www.f1technical.net/features/10586

1.) If the “lateral linkage” pivots by inflection from one wheel, it looks to have to affect the other wheel. I don’t see how it can’t – and I don’t see that as a good thing. The way I see it, the mechanism will increase chassis roll – not decrease it.
2.) The aft base of the third spring looks to be attached to the same object (transmission top wall) as the fore “longitudinal linkage” bar. I don’t see how suspension is affected by their non-independent base points. Even if the base pivots – what does that give us?

(Note - it’s also possible the longitudinal linkage also serves as a torsional bar – so that may assist rigidity.)

Here is another view – of an R26 – but it’s not helping me with #1 and #2 above.




Perhaps here the longitudinal linkage bar itself serves as a spring – and perhaps the bottom of the T is a torsional bar (as well as possible longitudinal torsion).



Then this shows the current “pull rod” version RBR is using – but no internals.
http://www.formula1.com/news/technical/2009/0/626.html

My head hurts. I’ll try again in the morning.

I'm feeling your pain. One thing the version on the R26 picture (2006) technically predates the the pieces that are being used now and that are described in the F1 Technical article.
Also keep in mind that an F1 suspension really doesn't travel very far, it's very stiff and has to be to resist maximum downforce. I did find this explanation on another forum which took me several readings to become clearer.

"One end of the spring/damper unit is connected to the back of the gearbox case, the other is connected to the 'T' bar arrangement.

In one wheel bump ( i.e. one wheel moves more than the other e.g. roll ), the 'T' bar assembly will twist providing a springing force. Note each rocker has its own damper assembly so this roll mode damping can be controlled.

In two wheel bump ( i.e. both wheels move same amount ) the 'T' bar assembly does not twist put pivots in the fore-aft plane about its lower end ( somewhere deep within the gearbox case ). In this mode, the separate spring/damper comes into play to control the suspension motion.

This suspension design is not that unusual on single seater cars, the idea is to de-couple the roll and bump modes. On a 'normal' car with 2 springs and an anti-roll bar, the bump mode is controlled by the springs whilst roll is a combination of springs and anti-roll bar. This means that the roll mode is stiffer than the bump mode, as it has the additional force of the anti-roll bar.

On a high downforce car, this is the complete opposite of that is required - you need a very stiff bump set-up to stop the car hitting the ground. With a conventional system , this bump springing required is way too stiff for optimum cornering grip. The de-coupled system, allows you to have the stiff bump springing required along with much softer roll springing for optimum cornering. The use of 3 dampers also allows independent tuning of the damping rates in bump and roll."

The other picture is of the front suspension which is needless to say 180 out from the rear.

If it's any more help picture what is missing here that you find in almost every car and truck an anti-roll (sway)bar. If you look at roll bars they rest in bushings and only connect at each wheel. Rolling forces are transmitted to either wheel.

A better explanation is here:

http://en.wikipedia.org/wiki/Sway_bar