Horizontal vs Vertical Suspension?

[jsnyder49428]

I've noticed some cars have horizontal suspensions, like this:

http://cdn.24.com/files/Cms/General/d/9 ... d78f08.jpg

Why? It seems to be more common on high end sports cars and I doubt they would do it just to look cool. Is there some advantage over a regular suspension like this:

http://www.ferraricars.org/img/ferrari- ... ion-03.jpg

[tommylommykins]

I'm no engineer, so feel free to shoot down any of my bombasting.

There is nominally no difference between the vertical and horizontal suspension systems there. You can set them up so they are basically identical.

There may be differences because of the fact that you can do some funky geometry by having more moving parts in between the spring and the point where it attaches to the wheel. The sort of thing you might be able to do here is make it harder to compress the suspension than it otherwise would be at the top or bottom of the suspension's travel.
Look at the wikipedia article on linkages for more information on this sort of stuff.

Because the horizontal setup doesn't doesn't have to have any effect on how the suspension works, it's possible that they decided to do this for better packaging of all tho components at the front, or to get easier access to the springs themselves.

Perhaps also, having the suspension arms meet in the middle aids rigidity a little bit, if you can get all the forces the car experiences into one place, then that's the only place that you really have to reinforce. The rest of the car could be made out of papier mache without having a negative effect

[Mystery Steve]

That's correct, for the most part, it makes no difference how the dampers are oriented. When the layout is designed, there are a few things to keep in mind:

1) Your kinematics need to work out so that you use the damper efficiently. That is, you want to use the full travel of the damper as the wheel moves through its respective travel
2) It needs to fit in the space provided. This depends on the layout of the other components. Consideration for mounting stiffness is also important if you want adjustments to be noticeable.
3) Speaking of, if the dampers are adjustable, it's a good idea to put them in easy reach so they can be adjusted quickly.

In short, the layout and location of the damper is really just a balance of these three points. Other than that, the location doesn't matter.

[Caito]

To add to what was said.

It reduces unsprung weight. In cases like a formula car, it gets the spring/damper out of the way aerodinamically. A push rod generates less drag than the whole coilover.

One advantage of lower unsprung weight:

[jake_m]

Another reason that inboard springs/dampers were adopted is to overcome the geometric effects of a narrow chassis. An outboard spring/damper must be leaned into a fixed mounting point on the chassis, if the lean angle is large the suspension forces quickly become nonlinear*. Any lean angle other than 90 degrees to the lower wishbone will have a softening effect as the wheel moves upward which is the opposite of what is typically desired (although this effect is minimal above say 75 degrees between the lower wishbone and spring axis).

To summarize in no particular order:
- Aero benefits: remove spring/damper from open air
- Suspension design: pull-rod/push-rod minimize nonlinearities in suspension kinematics
- Lower unsprung weight: a bit difficult to divine perhaps
- Adjustment: push or pull-rod suspensions make ride height adjustment easier
- Packaging and other issues: simpler anti-roll mechanisms, torsion bars instead of springs, rigidity, etc.


* The forces become nonlinear because for an increment of vertical tire movement (say 1cm) the length change of the spring/damper decreases as the wheel moves further upward. Taking a tire displacement of 1cm at ride height you may observe a spring compression of 0.5cm. However if you move the wheel 10cm up and measure the spring compression it will be less than 5cm, how much less depends on the lean angle. The Porsche 956/962 Le Mans racer counteracted these effects in its front suspension using titanium springs with a variable wind and variable wire diameter to produce a spring rising rate (increasing stiffness).

[mach11]

My experience in suspension is relatively primitive but I would like to share my thoughts based on some of my experiences in FSAE,

The cars with a horizontal suspension system offer a bit more of travel for the wheels when compared to longitudinal ones, (i might be wrong, do correct me)but the suspension effect is relatively less as there might be feedback on to the Chassis much more than what it is in the longi system.

In longitudinal suspension system, the "suspension effect" is more when compared to the horizontal suspension system. But it depends on the characteristics of the Damper and mounting.

But i must say, the topic is really interesting and i am sure members in this forum who have greater experiences can share their thoughts on this.

Thanks