Corvette leaf springs

[culver]

From what I have heard, you can do asymmetrical rates with these springs. I have not seen how. I would speculate it involves shifting the location of the spring mounts on the chassis. That is only speculation. However, I suspect that adjustability is if nothing else, different than working with standard coils and would likely require the race engineers to work on something new for a bit with potentially little pay off.

If F1 ever moves away from the current setup where most of their "suspension" is actually in the tires, I could see them using something like these leaf springs instead of coils. With the use of torsion springs they have already shown that they are willing to develop different ideas if they see any advantage in it what so ever. If the vehicle requirements and packaging allowed it I could see them using a compact, fiberglass spring in place of a coil or torsion spring. The fact that the fiberglass spring packs more energy per mass of spring than steal would be attractive to a team. I expect the actual implementation would look different than what we see in the Corvette. Given the silly high budgets of F1 these days I could see them paying the high price if it offered some bit of an advantage.

Any feedback on the illustrations? I seriously am soliciting feedback with the intent of making changes for clarification.

[henk4]

Originally Posted by culver

Any feedback on the illustrations? I seriously am soliciting feedback with the intent of making changes for clarification.

If allowed, I would like to make some feedback on the Wiki text. Reference to other cars is a bit bleak, in my spec sheet the Volvo 960 always used coils, the Fiat 128 dates from 1969. Its underpinnings may have been produced a long time as a Yugo, but AFAIK this might be the last case. (I don't know what GM W-Platform stands for). On the other hand you could add the Volvo 340, which used a variomatic driven Dion rear axle, suspended by two longitudinal leaf springs.
Of course (transverse) leaf springs have been used abundantly in the past, but have now been superseded. To avoid further discussion you may want to delete the section on perception/push rod engines....(I don't think we need discussions like: The world is wrong and Corvette is right on Wiki).

[Matra et Alpine]

Culver, that F1 hasn't gone back to transverse leaf springs kind of proves the point of the benefit of coils !
Packaging is a problem for tranverse leaf, though not insurmountable.
Where would you fit the damper ? WHen you take out the damper weight a spring of modern materials isn't that heavy.

The graphics are excellent and get over how it works as a spring AND anti-roll bar very effectively. Good job

Also, it's correct to say that you can alter the spring rate somewhat by moving the anchor points and altering the compliance at the pivots, but that will also affect the anti-roll bar component. It woudl require a much more complex sliding-sleeve on the leaf whci then creates stress points, so no real solution.

[culver]

Well I can't guaranty all the text as I didn't write much of it. The article is Corvette specific so I think it’s OK that it only mentions others in passing. It was originally part of the Corvette entry. I’m not sure why it was decided to make it a separate entry. I do think that the Corvette’s implementation of a leaf spring is different enough from the traditional style that it deserves separate mention.

The Volvo 960 wagon used leaf springs for packaging reasons.
volvo 960 leaf spring - Google Search
I really don't know much about Fiat's use of leaf springs. If I recall from, which I'm not doing well in this case, the Fiat use a metal leaf spring as both a spring and upper control arm. I have seen this on golf cars recently but I'm not sure about on road cars.
The GM W-body cars were cars for the North American market based on the "W-body" platform.
I partially agree with the point on perception. I would strongly argue that there is a perception gap. One has to look no further than the comment on the suspension when Top Gear reviewed their first C6. However, you are completely right that perception is not a technical point one way or the other. With that in mind it would be OK to pull the point.

Again, while I have edited the article in the past, as a Wiki entry no one person it 100% responsible for an article and anyone can edit it. My biggest concern is making sure people understand what I was trying to illustrate with the images. However, I'm also open to other feedback. And of course, anyone is welcome to edit the article themselves.

[culver]

Originally Posted by Matra et Alpine

Culver, that F1 hasn't gone back to transverse leaf springs kind of proves the point of the benefit of coils !
Packaging is a problem for tranverse leaf, though not insurmountable.
Where would you fit the damper ? WHen you take out the damper weight a spring of modern materials isn't that heavy.

The graphics are excellent and get over how it works as a spring AND anti-roll bar very effectively. Good job

Also, it's correct to say that you can alter the spring rate somewhat by moving the anchor points and altering the compliance at the pivots, but that will also affect the anti-roll bar component. It woudl require a much more complex sliding-sleeve on the leaf whci then creates stress points, so no real solution.

Has F1 moved back to coils? I thought they were still using torsion bars. Where I could see F1 using a leaf spring would be as a flexure based suspension pivot. It would have the benefit that you have no static friction in the movement (F1 cars already use flexure based joints in the suspension for this reason). It would also avoid the off axis loading issues that coils have when placed around a damper. Of course F1 teams have dealt with this in the past by using things like the Hyperco-ICP pivoting spring perches.

I do see the issue with changing anti-roll rates while changing spring rates. These are factors that aren’t an issue for a manufacture where you don’t have to spend as much time thinking about how hard is it to adjust this suspension on a weekly basis.

PS: Thanks for the feedback!

[RacingManiac]

The problem would still be in the adjustment of it, as it would necessitate changing of suspension arms or the likes when adjusting spring rate, where as you can swapout torsion bars no more difficult than coil spring....

[culver]

In the case of an F1 car I'm envisioning a spring/suspension flexure in one unit. I'm not saying I have all the details worked out, not even close. I'm only that I could see an F1 team using the technology.

[wwgkd]

Originally Posted by henk4

To avoid further discussion you may want to delete the section on perception/push rod engines....(I don't think we need discussions like: The world is wrong and Corvette is right on Wiki).

Well, getting slightly off subject it's not only the Vette that uses them. You can make an argument for the Viper being a brute force apporach, but it now has not only pushrods, but also variable valve timing. The Saleen S7, one of my all time favorite cars, uses 2 valves per with pushrods, too.

Seriously though, cool stuff in this thread. I didn't have the money to celebrate the end of projects for the semester by drinking, but I spent the night reading this instead. It was a great alternative. If I can find it I have an old printed copy of an article I found which discussed leaf vs torsion springs in 1,000ish pound cars. It is probably 6-7 years old by now, but at the time I was doing the research there wasn't a whole lot I could find on the subject.

[Matra et Alpine]

Originally Posted by culver

In the case of an F1 car I'm envisioning a spring/suspension flexure in one unit. I'm not saying I have all the details worked out, not even close. I'm only that I could see an F1 team using the technology.

Watch out as likely to fall fouol of the rules
A team had flexing parts but they were banned as they were deemed to be "movable aerodynamic devices".
If you kept the flex out of the airstream then I reckon you might get awy with it ... BUT .... what is the advantage ? How woudl the flex alter the suspension geometry and how woudl you control flex caused by torsion and flex by compression ? Too many difficulties I think ..... hence why springs have lasted 100 years

[culver]

Hey,

I have been of this forum for a bit. Sorry for the delay in getting back. BTW, some new info has come up since I last added this. I’ve added a finite element model of a leaf spring mounted as GM has done to the article. It shows how lifting the right side actually causes the left side of the spring to also move up.
Imageeformed spring model iso and plane.JPG - Wikipedia, the free encyclopedia

Also, there was a person who was arguing with me regarding the Corvette leaf spring acting like a live axle. The person had cited a MT article which stated something to that effect. Via the Motor Trend forum we found out what the MT editor had meant by his comment… and it was incorrect. He was basically assuming that because the two sides of the spring were connected, pulling up on the right would make the left go down like a seesaw. Completely wrong as the illustration above shows. Even the magazines get it wrong from time to time.

Matra,
The flex part and moving airfoils could be an issue. Of course the existing suspension arms do flex. All materials under load will flex to some degree… but most of the time the flex is so small as to not matter.

The whole flex idea has all sorts of implications. Mind you grand prix cars (and many other cars) in the past did use leaf springs as both spring and arm. Flexures as suspension joints are common in racing. F1 cars have used them at suspension pivots in recent years.

Opel’s racing version of the Astra did something similar. The rules for what ever class the Astra was running in said the car had to run the same rear suspension as the production car; a twist beam. Well the problem with twistbeams is their tendency to toe out the outside tire under hard cornering loads. The engineers were only allowed to have suspension “joints” where the existing Astra had them. So the engineers made a rather complex, triangulated looking twist beam that used a number of flexures. Like a real twist beam the assembly was supposed to flex as the suspension was articulated. However, unlike the production parts, this acted like solid links with pivots at the ends rather than a continuous, flexible structure. It was written up a year or two back in Racecar Engineering magazine.

Fun stuff.