Too complex for 7

[BusaNostra]

http://blogs.insideline.com/straightline/2011/09/2012-lamborghini-aventador-suspension-walkaround.html

 

....at the end of the day the simple 7 can keep up at the track.

Edited December 16, 2011 by BusaNostra

[S1Steve]

Busa, Thanks for sharing the suspension walk around, I am not sure what has blown my

 

mind more, Lambo or the MP4-12c.

Steve

[scannon]

Pure car porn. Thanks for sharing.

[DeanD3W]

smeaton1, oldcarsmell, and mk2mark all did a nice and polite job of pointing in their comments that push-rod suspensions do not reduce unsprung weight. They have other advantages, but higher unsprung weight is a disadvantage of using push-rods or pull-rods.

 

Very pretty components, but aren't those control arms too short to really be considered part of an excellent suspension design?

 

Dean

[BusaNostra]

if i remember my old audi almost has the same suspension design. having (something like) seven aluminum links. it's a money pit, if one goes expect the rest of the link to go....sort like a domino or italian sausage links. it's over engineered. but it's a breathtaking piece to see.

 

make it simple stupid....my preference.

Edited December 16, 2011 by BusaNostra

[Hank]

Couldn't the unsprung weight actually go down in an inboard suspension vehicle? Due to the ratios that can be achieved I would think the shocks could be smaller than units mounted outside the chassis. I know it really doesn't apply for the Lambo, but one of the major reasons for inboard suspension design was for the aerodynamic benefit of getting the larger shock/spring assembly out of the air and replacing it with a tiny carbon fiber rod instead. I agree, though, beautiful eye candy!

[Kitcat]

Very, very nice -until the over-exuberant owner slides it into a curb at speed.

[Croc]

Inboard suspension looks nicely simple on a seven:

 

 

http://mycaterham.com/mediac/400_0/media/DIR_175409/0049.jpg

 

http://mycaterham.com/mediac/400_0/media/DIR_175409/0106.jpg

 

http://mycaterham.com/mediac/400_0/media/DIR_175409/0105.jpg

 

Still uses the exact same shocks as a regular Caterham so no weight saving here, just the (ever so tiny) marginal aero benefit.

[MoPho]

It needs to be complex, it weighs over 4000lbs

 

 

I was at the press launch of the Murcielago LP-640 and we were able to take the cars out on the track, and despite hitting nearly 150mph on the straight, it was more fun to tell my friends about driving the car than actually driving the car.

It certainly was nice, but IMO the size, weight and luxurious appointment water down the experience, not to mention I didn't have the ability (and how many people do?) nor the wallet (and how many people do?) to drive it to the limits, do you really want to write off a $400+k car at 150mph?

Cars like this are also not that exciting on the road, you can by far break the speed limit in 2nd gear, so you end up driving a really fast car slow

 

That said, I was later taken for a ride with an Indy car driver at the helm and he pushed the car pretty hard we were sliding around corners, up on two wheels, late braking, etc., it was pretty exciting but at the end of the day it took an indy driver to get the car to be almost as fun as the Caterham is with me, a mere mortal, behind the wheel

 

Lamborghini's sure make nice jewelry though

[Sean]

Still uses the exact same shocks as a regular Caterham so no weight saving here, just the (ever so tiny) marginal aero benefit.

 

And the not-so-tiny benefit of going from the falling rate geometry at the front with Caterham's standard widetrack suspension to a rising rate geometry.

[JohnK]

Inboard suspension looks nicely simple on a seven:

. . .

Still uses the exact same shocks as a regular Caterham so no weight saving here, just the (ever so tiny) marginal aero benefit.

 

Yes, the Caterham's implementation is pretty!

 

The advantages of getting the mechanicals out of the air-stream aside, suspensions with more complicated mechanical arrangements generally are done to provide for greater flexibility in tuning the suspension. Simplest e.g. being able to change the curve of the motion ratio for rising or falling rate, and similarly the MR of the anti-roll bar. All I have read indicates that, while there are a large number of fundamentals that must be well-understood and taken into account, suspension performance is still a black art and from the git-go and only most conspicuously is a compromise between the bad effects generated by camber, scrub and caster in roll and bump. There was a PBS special on a while back about the Penske Indy team's development of their car. The take-home was that, even with huge resources and a large and talented team, they were unable to get the car to handle properly (push/loose) at higher speeds.

Wm.C.Mitchell's WinGeo3 allows you to look at how the suspension moves from many different perspectives and conditions and, if you have the patients to measure your car, you can give yourself a baseline to work from and explore changes. Watching how things mover around on your own car is great fun, but figuring how that translates into lap times on the track, it's still is a black art.

[Automoda]

That Caterham's suspension is beautiful. Now thats a car. I dont know what to think of the Lamborghini. I suppose if i were going 200 mph I'd like beefy suspension, except that real F1 cars seem to have spindly suspension like the Cat, not the Lambo.

 

One thought I've had about the inboard suspension-- The more joints you have, the more inefficiency you create. You're moving force into a 140 degree change of direction .... so there has to be some kind of affect on the feel of the suspension, right? Plus the more little joints you get, the more chance of getting a few miliseconds of 'lag' in the works. I'm not sure what this would mean in real life but adding complexity to a system that has to respond in real-time and efficiently seems like it'd have its downside.

 

Its my understanding that you want to use mild steel in the suspension since it bends without breaking and is more or less immune to vibration cracking... While aluminum will develop cracks with vibration and would rather break in unpredictable, sudden ways. Of course perhaps this is not true with all alloys. But what are they accomplishing with all that aluminum? A small weight savings? It looks like those solid castings must weigh something close to what a hollow steel tube would weigh, but cost 50X as much to replace if you hit a curb. I do like the adjustable shims on the mounting points. Is it necessary to have ball joints that look like they'd fit a large cement truck though?

[speedwagon]

Think of unsprung weight as components that are subject to inertia no matter where they are located. Shock absorbers are an attempt to control inertia and if you reduce unsprung weight it makes their job easier. All suspension geometry is to maintain the most ideal tire contact for the largest percentage of time particulary in the most critical positions. to me inboard brakes make the most sense except for cooling. on the other hand; cars with live axles run pretty close to the same times and perhaps simplicity is best-- wait I just described a 7.

[HankMauel]

Inboard suspension looks nicely simple on a seven:

 

 

http://mycaterham.com/mediac/400_0/media/DIR_175409/0049.jpg

 

http://mycaterham.com/mediac/400_0/media/DIR_175409/0106.jpg

 

http://mycaterham.com/mediac/400_0/media/DIR_175409/0105.jpg

 

Still uses the exact same shocks as a regular Caterham so no weight saving here, just the (ever so tiny) marginal aero benefit.

 

 

Which explains why the shocks are mounted upside down...an upward movement of the wheel/tire now results in a downward movement of the (internal) suspension arm. Bounce and rebound movements are reversed from standard outboard shock position.

And I only had to scratch my head for a few seconds to realize that while looking at the photos. Not bad for a sleepy Saturday morning!:smilielol5:

[notakit]

Unless you have a pressurized gas/air type shock,

I don't believe it matters whether a shock is mounted "upside down" or not. I think this particular application was dictated by the springs to clear the steering rack.

[notakit]

Upon taking a second look, the shocks do not appear to be upside-down after all. I think the logic to keeping them upright for this suspension is so the lighter half of the shock is moved through the suspension's range of motion, not the heavier half which is properly "fixed" to the frame.

[Mondo]

Real benefit... it's easier cleaning a single bar of bugs than a shock & spring

[HankMauel]

Upon taking a second look, the shocks do not appear to be upside-down after all. I think the logic to keeping them upright for this suspension is so the lighter half of the shock is moved through the suspension's range of motion, not the heavier half which is properly "fixed" to the frame.

 

After a cup of coffee I, too, see the shocks mounted "normally"...piston rod up and valve unit down.

This still poses the question as to compression and rebound rates.

Way back in the dark reaches of my mind, I remember something about "jounce" and "rebound"...circa the 1960's. There were discussions that the two were different rates.

I went looking at gas pressure shocks and see a variety of input. SPAX coil overs, like on my Seven front end, do indeed have an adjustment for "stiffeness" and it does the bump and rebound simultaneously...up or down over a range of settings.

Koni shocks...at least the competition units...have a separate adjuster wheel for bump and rebound. See here: http://www.koniracing.com/images/File/2812_Reference_Sheet.pdf

 

Without a clear view of the shocks on the Seven chassis, I can't tell if they are adjustable or not. I would guess that they are adjustable and along with spring perch changes can alter the suspension for various handling needs at different tracks.

 

Perhaps the owner of the car can shed some light on the subject.

Still, it is a very trick setup and much simpler than the Lambo. And we all know "simple is good".

[speedwagon]

most shocks need to be upright for the fluid to drain down, but some are designed differently. just noticed the sway bar linkage and adjustment, this is a well engineered and quite light weight car.

[notakit]

I dont think rebound and damping, adjustable or not matters whether the piston is up or down. My reasoning is IF it's a sealed unit there is no "draining." because it's only oil inside passing through valves. This is different than forks, say on a motorcycle where you can add damping and/or rebound with air pressure. Then the shock IS directional because air is too thin for the valves to dampen.