Ultra Tech: Would A Torsion Shock Improve Ride/Handling?

To make it simple-A spring is a spring is a spring. All springs are simple energy storage devices, the amount of energy stored is a function of material type, material volume and to a degree-the shape/design of the spring. But the shape of the spring is not the critical factor for energy storage. The shape comes from other issues, such as packaging.

A standard coil spring, if unwrapped starts becoming a pretty equivalent torsion bar. (The are both functionally identical, only packaged differently.)

The standard coil spring works pretty well for cars, but the torsion bar is used quite frequently in F1 nowadays-but this is purely a packaging issue, not due to any superiority in energy stoarage.

The type of spring has no influence on ride/handling.

 

My machine book is at work, but it I recall correctly, a coil spring is the best for energy storage per lb, a leaf spring the worst.....I just don't where remember a torsion spring falls, although intuitively I'd guess about the same as a coil.

A torsion spring can easily be mounted along the bottom of the chassis, lowering the center of mass, but requiring the chassis to carry the load over a relatively large area, requiring a stronger chassis. I'd have to do some math, but a torsion spring probably has an unsprung weight advantage in that about 1/2 the mass of a coil spring is unsprung weight and moves with the wheel. A torsion spring doesn't translate, but does have a rotational inertia term that would generate some effective unsprung weight, but since the diameter is small, my guess is that it's a significantly lower number than a coil spring.

But as you said, normally it just comes down to cost and packaging.

 

Chrysler used torsion bar suspension into the 1970s. Of course it was used on the old VW Beetles. Former Porsche engineer Jobst Brandt has written somewhere in here http://yarchive.net/car/index.html that torsion bar suspension is only appropriate for amored vehicles (military) and not automobiles.

 

i just thumbed through my machine book and for cars of street weight it's not what i'd call a viable option. the leangth and wire dia needed would offset the supposed gains. then you have the inner support rod that needs to mount to the chassis. for F1 there low weight and exotic materails allow for the design. for an automotive set-up i'd probable use right/left wound for either side of the control arm, however that can be costly to manufacture.

 

I'm not sure I understand this one. Torsion bars have been and still are used on everything from VW bugs to 5000 lb Cadilacs and pick-up trucks. Coil springs are easier to mount and easier to keep friction/stiction low than with torsion bars. I'm not sure which has a weight advantage...I'd guess coils if compared to solid torsion bars, but torsion bars if hollow bars are used. I'm pretty sure a well designed torsion bar set-up would have the lower upsprung weight, but I'm not so sure that's true with the stuff I've seen in on production street cars...cadilacs and trucks which use(d) massive lower conrtol arms to transmit the torque loads.

 

i thought you guys are talking about torsion springs! that's what garage doors use. it seemed odd to me that one would want a torsion spring for a car.

 

for those not faimilar with torsion 'bars'
http://en.wikipedia.org/wiki/Torsion-bar

the problem is the stress is from bending not torsion for torsion springs, a torsion bar is resisting the 'twist' a torsion spring is un-coiling if you will. different design and different again from a coil spring.

so re-cap:
cars use torsion 'bars', and some valve train assy use torsion 'springs'

 

Yes, quite right....

and there are have been valve trains that use torsion bars.

 

i've always been intrigued by the various desmodronic versions for the valves, i'll see if i can dig up the dwg showing them all.

 

aah yes, the no springs at all trick....well I guess it's actually a form or torsion spring or bar because I think the return cam runs at less then zero clearance causing flex in the return mechanism.....which means it's acting as a spring I guess.