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

 

Interesting link, it's a shame it only mentions full compression and droop of the suspension, rather than the effects you'd get when hitting a pothole or rock with one wheel.

 

other than lower unsprung weight, it really doesn't cover that eh?

 

Golden your theory is all wrong... Put the back half of the car on jack stands. Place your jack under the drivers side shock mount and start jacking it up. Tell me what the passenger side of the spring does..

 

I don't need to, look at the link Jason kindly put up.

http://www.vettemod.com/forum/showthread.php?t=2302

 

It won't let me look at the link Jason put up, but it seems likely to me that if you do as Vette_Xpress said the passenger side of the spring will do nothing.

 

The link you can't open is an interview with Leland Decker, GM designer, explaining how the centre section of the mono spring changes shape and transfers load between sides under different conditions.

 

I've been in two cars that had them, mine doesn't. They ride a little nicer but my car with the cut 550 coils handles better. But I'm sure with a high enough spring rate they would handle just as well.

If you want a nice ride but you want it to handle, go big on the front sway bar. And get a decent rear sway bar to match. But go a little softer on the springs.

 

Vette_Xpress and Priya if you sign up to vettemod.com the link will open and you can see that mono leaf springs are not independent side to side.

 

We do this all the time with anti-roll bars. The system as used on the Corvette (which I think was first used by Fiat) is a great design.

I think something that isn't clear to many people is what independent suspension really means. It a rather poor term because it implies movement of one side doesn't affect the other. However, that isn't how it's used. As the term is used on cars it means geometric motion of one wheel doesn't change the position (caster, camber, etc) of the other wheel.

However, all cars for the most part WANT some level of interaction between the left and right wheel. That is exactly why we have anti-roll bars. An anti roll bar effectively transmits forces from one side of the car to the other. This system does the same thing. The only difference is it doesn't look like a traditional U shaped anti-roll bar.

Yes, the transverse, dual pivot leaf spring does provide some anti-roll effect (the rear springs on the C2-C4 were truly left to right independent as they were rigidly clamped in the center). However, those forces can be calculated and worked out into a roll rate. Once you know the roll rate contribution of the leaf spring it is simply added to the roll rate due to the anti-roll bar and you now know the total system roll rate.

The system is miss understood but actually is an excellent design. The one and truly only killer flaw, the reason why just about every car doesn't use this system, is cost. The fiberglass spring is simply more expensive. Yes, it saves weight and in some cases packages better than a coil spring. However, in most cases the cost benefit analysis kills it in favor of traditional coil springs.

 

Those effects that you mentioned are the same regardless of spring type. The rear spring rates at the tires are defined by a ride rate and a roll rate (ignoring shocks and tire related rates). The tires and chassis for the most part don't care what those springs look like, they care what the effective rates are.

 

Have you quoted the wrong post? Your post has no correlation to mine, it makes no sense.

 

Yes I did, sorry. This is the one I meant to quote:

 

That still makes no sense, why are you talking about, what I assume are wheel rates when I'm talking about the load on one side of a mono spring effecting the spring rate of the other???

 

Unless I misunderstood your post (which is possible) you are suggesting that connecting the left and right side together via this spring creates a problem when you hit a bump with one wheel. I am asking why you think the use of the leaf spring makes this different than a system with coil springs.

I'm saying that from the point of view of the tires, they don't know or care what combination of springs are pushing them against the road. In the end the spring loads on the tires can be thought of a wheel rate and a roll rate. It doesn't mater what the linkage and springs look like. Now in the case of the Corvette the ride spring rate is mechanically coupled to the other side of the car. However, we basically have the exact same thing with a conventional coil spring setup. I compress the left wheel. That twists the anti roll bar and which then pushes up on the suspension on the other side. Net result, the instantaneous spring rate acting on the other wheel is reduced.

The long and the short of it is there is no fundamental dynamic disadvantage to the leaf spring as used on the Corvette. That doesn't mean people will be happy with the factory spring rates nor does it mean the factory shocks are good or bad. The only fundamental problem with the leaf spring is the high cost of the part.

 

My conversion to the V.B.P. suspensions have been a very positive investment for my car...one of the unstated quailities of the mono spring is how the fiberglass strands are arranged in the manufaturing process...once you have researched this...your decision could be ....how fast can I get these onto my car...I feel that both component assemblies
have redefined my understanding of "Performance Suspension".

 

Almost completely off topic, but something I've been wondering...

What is the "life span" of a monoleaf? Is there a danger, for fiberglass models, of it ever just cracking or breaking? Any actions that would reduce or increase longevity of the spring?

 

You've made so many assumptions.

You've assumed that a sway bar is essential.
You've assumed that a sway bar has to work through the entire suspension travel.
You've assumed that a sway bar has the same resistance throughout it's travel.

If you take the two extremes, a car with no front sway bar and coil springs and a car with a monoleaf and no sway bar, the car on coils has truly independent suspension.

Take both cars onto a rough surface and the car on coil springs will massively out perform the mono spring because the wheels will be allowed to follow the contours of the road independently. The monoleaf by comparison will cause wheel skip and body pitch and roll as the two sides of the spring interact unevenly together.

I'm not saying the monoleaf doesn't offer a good compromise, working as sway bar and springs but it wouldn't be my idea of an 'upgrade'.

 

Assuming the epoxy doesn't fail the spring should last the life of the car. Fiberglass springs are used for some heavy trucks in part because their cycle life is effectively infinite. However, they can fail quickly due to exposure to chemicals or heat which can degrade the resin.

 

I think we need to clear up your definition of independent suspension. In automotive terms "independent" suspension only means the path that a wheel travels as you compress the suspension is not affected by the position of the other wheels. So long as the wheels are connected to the same chassis you will never have truly independent suspension where the actions of one wheel can not be felt or observed in the others. Basically NO car has truly independent suspension.

I've made no such assumptions. A sway bar may not be needed. However, I am assuming that we are comparing mono-leaf + sway bar to a case where the alternative is coils + sway bar.
Aside from off road vehicles I can't think of a single vehicle road car where the sway bar doesn't work over the whole articulation of the car's suspension. Perhaps we are misunderstanding each other. If so please tell me which car has this feature.
I actually made no claims about the sway bar resistance through its travel. I would actually assume that most swaybar systems (including what we see on the Corvette monoleaf) have a spring force that follows F=k*(difference between wheel positions). The force is linearly proportional to the difference in wheel positions. This would be the same spring rate but not the same force.

That might be true. However, the lack of a sway bar would in most cases hamper the car in almost all measures of handling. Once you add the sway bar to the coil design you have the same issues as the mono-leaf.

It's not at all a compromise. It basically does the exact same thing as a pairing of coils and traditional sway bar. It can be considered an upgrade because it weights less for the work it can do (more specifically, it weighs less for the energy it can store).