Why are Modern road cars set up so stiff

[Smokes]

I hope Richard Parry-Jones will beat the marketers with a baseball bat and give us brilliant handling cars like the focus and fiesta again.

[Greg Locock]

RPJ retired years ago.

[Jersey Tom]

I think one of the trends that is being ignored is the one towards better handling.

UK car magazines worshipped BMW for so long that everybody in Europe moved towards better handling, at the expense of ride. For a given architecture the two are more or less direct tradeoffs, if you want better ride and the same handling, or vice versa, you can't tune it with springs sta bars and shocks and bushes (assuming the original setup was competent), you have to change something more significant (most easily and most expensively the tires).

This is, of course, crazy. Most people drive so far within the limits of the car most of the time that all they get from that compromise is rattly cars and bent wheel rims, the positives from the improved handling are rarely experienced. OK, I do think that a modern car is a better one to avoid an accident in, it'd be interesting to see data on whether real people do actually drive themselves out of danger using 0.8g, or if they just point the car in the right direction and brake very hard. I suspect the latter.

Hmm. Think it still depends by OEM and market. Hell, depends on your definition of "good" handling! I can think of one OEM/project putting a BMW sedan as their reference standard / bogey. I can think of another where the end outcome of a RWD sportscar was a totally numb front end and diabolical amounts of understeer, which I think was attributable to the use of a competitor's tires

Though I'd agree, most probably just smash the brakes in any sort of emergency "maneuver" !

[neilbah]

certainly in europe during the 80and early 90s many compact and medium hatchback models came in under a tonne which is a rarity these days with all the safety equipment,insulation and generally extra metal used in these bulkier bodies. I mean compare a mk1 Golf 800KG with the current model @ up to 1400KG..

[Greg Locock]

For which you get several airbags, and the structure to hold them. Bigger wheels bigger tires bigger brakes. Stiffer body. Bigger car. Bigger inside. A sound system not a radio with two speakers. A climate control system, not just a heater. side intrusion bars. far better crash performance. Five gears. Electronic gizmos. Fast glass. power steering. 84 instead of 49 hp.

etc etc. Also your curb weight for the Mk7 is wrong, they start at 1200 kg.

[DaveW]

I have recently driven a lot of modern road cars nothing sporty, one thing annoys me is they are set way too stiff, so every bump (incuding the road undualations created by the road rollers) get fed into the chassis and not into the dampers.

Ride quality depends on many factors which include tyres, springs, damper "shape", suspension isolation, and mass (as others have noted). The perception of ride quality is rather more complex. It depends upon structural integrity and build quality because (arguably) the ear is a remarkably sensitive "transducer".

It is also true, I think, that road cars are now increasingly biased towards handling (as Greg noted), perhaps driven by regulation (the lane change manoeuver for example).

The elise also has a relativly soft setup which makes the ride smooth but is still quick on the track. How did they do this?

Objectively, the Elise has a stiff set-up, so the short answer to your question is they don't. Here is the evidence. The plot contains estimates of "Comfort Rating" (CR) plotted against Heave mode natural frequency (FoH) for a range of road vehicles all taking during a rig test. CR is an accelerometer based measure of transmissibility (lower is better), whilst FoH is a measure of stiffness/mass. The trend line shows a very rough correlation between the two parameters. Over-plotted is the result obtained from the Elise, compared with a few other examples.

So why your perception? I don't know, but the car has a good structure, and it could be that you sampled it open-topped (i.e. without the sound box, and with other distracting sound sources).

[Greg Locock]

I haven't driven an Elise, but I did spend a day in my SiL's runabout, a VX220 which I imagine is similar. Personally I thought the impact harshness and shake was completely unacceptable for a daily driver, nowhere near what we were aiming at with the FWD Elan

Your plot is missing, Dave.

[marcush.]

I remember driving the Speedy with the original Ohlins package back then it was just horrible,close to what the series dampers did .
We certainly found setups that behaved very well on your german 3rd order country roads .I never drove the elise or a speedster in foreign countries though but did drive my Mini frequently to the UK .again and again i was gobsmacked how the impossible Mini changed completely his character as soon as you had crossed the channel....

[DaveW]

Your plot is missing, Dave.

It loaded for me OK just now. It is a .png, if that makes a difference.

Marcus: Mini character has something to do with a motion ratio of around 4, perhaps. I should have added motion ratio to my list.

[gixxer_drew]

one thing I noticed when I worked in the automotive industry was that the marketers listened to the customer demands of bigger wheels and lower profiles tyre and a sporty ride.
So i guess the engineers gave the customers exactly what they wanted.

I'd rephrase it to say... the engineers deliver what the marketers want, and the marketers want whatever they can sell the customer. But yes, the customer (particularly those with disposable income) think that big wheels and slim sidewalls and stiff springs are good.. so they'll pay for them.

Customers are weird, and the way they survey them is even weirder. What they answer on a questionnaire or focus group I think is totally different to real world reality or how things would go down on a showroom floor.

[Greg Locock]

True, which is why to be honest most vehicle dynamics targets are set by 'experts', or by comparison with known, good, cars.

Thanks dave i can see the plot now, I couldn't see the link before.

[Tommy Cookers]

it seems that small cars are not made these days
rather something called a city car, that is a small car with a body so shortened at the rear that it just covers the rear wheels
laden with driver only the weight distribution must be about 75 : 25, worse even than the original Mini
at low speeds it feels as if the wheels are bolted directly to the body

given that such cars rear suspension is intended to accomodate up to 5 occupants, can they ever ride properly 'driver only' ??
no 2 seater could have such poor weight distribution, and so would appear able to have a better ride ?

[autogyro]

it seems that small cars are not made these days
rather something called a city car, that is a small car with a body so shortened at the rear that it just covers the rear wheels
laden with driver only the weight distribution must be about 75 : 25, worse even than the original Mini
at low speeds it feels as if the wheels are bolted directly to the body

given that such cars rear suspension is intended to accomodate up to 5 occupants, can they ever ride properly 'driver only' ??
no 2 seater could have such poor weight distribution, and so would appear able to have a better ride ?

Having worked on the original mini development and raced them for years I can say you have a good point Tommy.

It is interesting to look into the future where electric city vehicles will be far better served for weight distribution and therefore potential for ride comfort without handling compromise.

[DaveW]

I haven't driven an Elise, but I did spend a day in my SiL's runabout, a VX220 which I imagine is similar...

Your SiL's runabout (according to my test) is rather worse than the Elise. Its FoH was lower (1.98 Hz) but its CR value was higher (6.68). The latter was caused by unfortunate power train dynamics that resulted in an effective rear mass of just 17 percent of static at 16 Hz, not far away from the rear hub mode natural frequency.

[Greg Locock]

Ta, hmm so about twice as bad as it should be for a given heave frequency.