What makes a good chasis?

[beast20vt]

yeah but the s2000 isnt a good handling car because its too snappy on the limit,theres no progressiveness or warning that its about to do it although i only drove the older version so dont know if the update sorted it or not

 

[Simon]

yeah but the s2000 isnt a good handling car because its too snappy on the limit,theres no progressiveness or warning that its about to do it although i only drove the older version so dont know if the update sorted it or not

How long did you drive it for? Its not snappy, its just rear wheel steering working, once understood it is very handy for getting the car around bends quickly, lift off mid corner and the car punishs you for being a tool. All the crashes of them going backwards through the hedge is due to driver error, of course though everyone blames the car. I've had mine about 3 months and I would say i'm getting pretty close to knowing the limits of the car, you certainly won't pick that up on a quick drive

Updated version is softer for joe bloggs with a smaller ARB on the back and revised geometry and pick up points, the early ones are a lot rawer and more of a race car for the road. As said though the rear wheel steering really needs understanding before you can think about driving one fast

 

[ramirez]

simon, is it passive real wheel steering with soft bushes or something like that?

 

[Simon]

Yes, passive RWS is probably the most useful thing Honda invented, apart from 4WS.

(Acutally, it was discovered by FIAT in the 60s, but Honda turned a disadvantage into an advantage)

When you apply throttle in a steady state corner, the outer loaded wheel pulls forward, increasing toe in & resisting oversteer. lift off, it toes in less, the car turns into the corner.

Find a big roundabout & practice steering round it at moderate speed, using only the throttle & not the wheel.

With practice, you can easily balance an S2000 into beautiful four wheel drifts. Accurate throttle balance is alos the key to not reversing through hedges backwards.

Interestingly, the principal works on Civic/Integrae, S2000s NSXs. Three utterly different layouts, yet the throttle steer in what makes them great handlers. Double wishbones help too, of course.

Must be compliance in bushes

 

[beast20vt]

yes but in the s2000 you dont feel when its close to happening so it isnt a very forgiving car!in say a caterham you can feel the back end when its about to start a slide which is good handling
must admit im not really an s2000 fan,i like the look of them and the engine is a masterpiece but its just got no torque for its weight so its too easy to get caught out and have to drop 2 gears plus i murdered one in my old 20vt

 

[penski]

Rank Torsional Rigidity Nm/°
1 Rolls Royce Phantom 40500
2 VW Phaeton 37000
3 Audi A8 4.2 Quattro 36000
4 Ferrari F50 34800
5 Mazda RX-8 30000
6 Koenigsegg CC 28100
7 Pagani Zonda C12S 26300
8 Pagani Zonda C12 25500
9 BMW Mini Cooper 24500
10 MG ZT Sedan 24250
11 Gallardo >23000
12 Volvo S60 22500
13 Audi A4 22000
13 Saab 9-3 Sedan 22000
14 911 GT3 >20625
15 MG ZT-T Wagon >20000
16 ULSAB 19056
17 Audi TT Coupe 19000
18 Opel Vectra C 18000
18 Zonda Roadster 18000
19 BMW E46 Touring 17600
20 911 (996) Coupe 16500
21 BMW M Coupe 16400
22 BMW E46 Sedans (non-M) 16000
21 F550 Maranello 14715
22 BMW E39 15152
23 BMW Z4 14500
24 GTM Libra 14000
25 CLK Cabrio New 12378
26 Opel Vectra B 12000
27 Audi A2 11900
28 USA 1997 Current Average 11531
29 Saab 9-3 Convertible 11500
30 911 (993) Coupe 11380
31 CLK Cabrio Old ~11050
32 Alfa 156 11000
32 Elise 11000
33 BMW Z8 10500
34 BMW E36 Touring 10900
35 Fiat Bravo 10800
36 Audi TT Roadster 10033
37 BMW E36 Sedans (non-M) ~10000
38 Renault Sport Spider 10000
39 BMW 7 Series 9531
40 Lotus Elan 7864
41 Diablo 6500
42 1962 Lotus Elan 6101
43 BMW Z1 >5600
44 BWM Z3 (non-M) 5600
45 1954 Mercedes W196 5423
46 Ford Escort Cosworth ~4500
47 1957 Lotus Elite 4067
48 1962 Lotus 25 F1 3254
49 1962 Lotus 24 F1 1356
50 1961 Lotus 21 F1 949

Quite an interesting list. Of course, torsional rigidity is not the be-all and end-all of chassis design but the stiffer the chassis, the easier it is for the suspension to work correctly.

Of the few there I've driven, the one which stood out the most was the GTM Libra - it's a sweet little thing and a true daily driver. I'd love to own one...I'd certainly pick it over an Elise.

Anyone else had a spin (whether literal of figurative ) in one?

*n

 

[Firestar_3x]

Nope but we did think about building one a few years back, guy up the road has one.

 

[penski]

Found a couple more figures:

The core of Libra is a tub-like chassis weighing just 98kg and yet has a torsional stiffness of 14,000Nm/degree, which compares with 68kg and 10,133Nm/degree for a bare Elise chassis.

When you take into account that the Elise uses a heavy steel subframe to mount components on and the Libra mounts them all directly to the chassis, the GTM becomes an ever more attractive prospect...

*n

[Edit - the Libra's fully-adjustable from the Factory too ]

 

[Del Lardo]

You should try an Elise then, 100x better

Until you bought your Elise I often wondered how much better the Elise was than the MR2. I always suspected that it was a league ahead but didn't want to cause an unjustified stir given how highly rated the MR2 is.

 

[beast20vt]

Quite an interesting list. Of course, torsional rigidity is not the be-all and end-all of chassis design but the stiffer the chassis, the easier it is for the suspension to work correctly.

which is shown by how bad a handler the torsionally stiff audi tt is

 

[digitalwolf]

I'm not sure, but the french seem to have mastered it on hot hatches.

I've never,ever felt my vtr body roll, it has soo much grip it's never ending.

Lift off though =S

 

[Simon]

If we are talking of chassis we should be looking at technical details and stiffness. Suspension shouldn't be a factor. Not surprirsed the BMW mini is up there, they feel very 'tight'.

The TT roadster must feel soggy as hell after driving the TT coupe.

The Elise is a lot lower than I would have expected though

 

[Jonnycoupe]

Found a couple more figures:



When you take into account that the Elise uses a heavy steel subframe to mount components on and the Libra mounts them all directly to the chassis, the GTM becomes an ever more attractive prospect...

*n

[Edit - the Libra's fully-adjustable from the Factory too ]

You seem to overlooking the Elise has no roof?

 

[silversurfer]

If we are talking of chassis we should be looking at technical details and stiffness. Suspension shouldn't be a factor. Not surprirsed the BMW mini is up there, they feel very 'tight'.

Nissan Micra has a good chassis in that case, terrible suspension (except over speed bumps, its great on those) but it can handle well considering.

MG ZT in the top ten rigid chassis!

 

[penski]

You seem to overlooking the Elise has no roof?

That's irrelevant - it's strength is in it's chassis. Not it's body panels.

Remember that list isn't an all-encompassing one; it just gives some good numbers to compare with.

*n

 

[Simon]

That's irrelevant - it's strength is in it's chassis. Not it's body panels.

Remember that list isn't an all-encompassing one; it just gives some good numbers to compare with.

*n

The Elise would be a lot stiffer if it had a roof, it is not a body panel its the chassis.

What would the GTM be with no roof ?

 

[Jonnycoupe]

So far from irrelevant its not funny. The roof of any car is pretty integral to its stiffness. Were not talking yank cars here with chassis frames and body shells that drop on.

Think of a car with no doors on, the roof plays a huge role by thickening the section of the car massively!

 

[Guigsy]

Lots of bikes have started to REDUCE stiffness in certain areas to improve feel and grip. It's been happening in MotoGP for a while. Frames are reworked to be less stiff along certain axes. Obviously having a floppy chassis isn't good, but the highest rigidity isn't always the best.

That table of torsional rigidity... I'd guess they clamp one axle and twist the other. Shorter cars are going to have an advantage. Also, aluminium is a hell of a lot less elastic than steel (doesn't mean it's as strong though). These two factors may explain why the Audi A2 is in there....

 

[Jonnycoupe]

On something that corners with slip angles you want a stiff chassis.

Aluminium is good as you can add plenty more thickness to increase the second moment of area without any weight penalties. Strength to weight is where it excels but you have to over engineer it a fair bit to avoid fatigue issues.

 

[silversurfer]

The Elise would be a lot stiffer if it had a roof, it is not a body panel its the chassis.

Thats the exige then..