<VV> Steering

[Alan and Clare Wesson]

Wrote this for another group I am in, but I thought I would send it to VV 
because the Corvair had the potential to have the best steering in history, 
but they blew it by gearing it unnecessarily low. I would be interested to 
hear the comments of the group - particularly engineers and people who know 
about steering and suspension design.

These comments apply to European cars (in particular the 1955 car I have in 
mind is the Lancia Appia, but those figures are also typical of most 
smallish (1100cc) European sedans from that era, most of which have 
FANTASTIC steering in comparison with the modern rubbish), but if you change 
the figures and dates a lot of them apply to American cars as well.

Cheers

Alan

P.S. Sorry about the metric measurements. Like most Brits I use Imperial, 
but this was written for a metric group.


Steering is the single most important aspect of vehicle design (apart from 
the gear lever and the seat base it is your only point of contact with the 
vehicle). And the tyres, your interface with which it controls, are your 
only point of contact with the road.

And it is the issue where I can best illustrate my oft-repeated statement 
that new is not necessarily better (in fact in the case of steering new is 
definitely worse).

The three issues governing steering quality are weight, feel and gearing. 
The weight of the steering is influenced by three things: a) the weight of 
the vehicle; b) the width of the tyres; and c) whether the car has front-, 
rear- or four-wheel drive. A light vehicle with narrow tyres and rear-wheel 
drive will naturally have light steering. If you increase the weight of the 
vehicle, the width of the tyres or switch from rear wheel drive, those 
factors will result in an increase in weight at the steering wheel rim.

The way that the weight of the steering at the wheel rim can be controlled 
(i.e. reduced) is by making it more low-geared (i.e. increasing the number 
of turns from lock to lock). The ideal is 2 - 2.5, because that means you 
almost never have to 'shuffle' your hands round the rim, and can turn the 
wheel very fast in an emergency situation. In the 50s most cars had narrow 
tyres, rear-wheel drive and 2-3 turns from lock to lock, and the steering 
was fantastic - extremely 'nervous', and giving you a sense of intimate 
contact with what was happening under the tyres (which, if you think about 
it, is pretty important from the point of view of controlling the vehicle, 
as it is your only feedback of information about the road surface you are 
travelling on). So if you encounter a patch of ice, mud or oil, or the car 
begins to slip or slide for some reason (intentional or otherwise...), you 
are instantly aware of it and able to control it.

Here is a timeline explaining how those issues have been compromised by 
industry developments, and why the steering on cars circa 1955 really was 
better than it is now.

1955-65 - rear wheel drive, average weight about 750 kg, tyre width about 5 
inches, gearing 2-3 turns. This was the golden age - it would be very hard 
to improve on this.

1965-75 - rear wheel drive, average weight about 850 kg, tyre width about 
5.5. inches, gearing 3-3.5 turns. The slide from perfection is beginning, 
influenced at first by increasing weight and slightly wider tyres.

1975-85 - rear wheel drive, average weight about 800 kg, tyre width about 
5.5 inches, gearing 3.5-4 turns. A bit worse than 10 years before but not 
much.

1985-95 - front wheel drive, average weight about 950 kg, tyre width about 6 
inches, non-powered steering, gearing has to be quite a bit lower to 
compensate for the extra weight, FWD and tyre width. Mostly 4-4.5 turns lock 
to lock, which feels very low-geared when being driven, and means that if 
you lose grip on a slippery surface you are unlikely to be able to turn the 
wheel fast enough to 'catch' the car. Andrew's Clio is one of this 
generation, and although Renault are better at engineering steering than 
most, I surmise that it will be around 4 turns if you go out and twirl the 
wheel.

1995-2000 - front-wheel drive, average weight about a tonne, tyre width 
6-6.5 inches, hydraulic power steering. Gearing can be improved because of 
the power steering, and so goes back to about 3 turns lock to lock (Alfa 
Romeos are 2, which is the best available). Satisfactory 'feel' because the 
hydraulics allow that, but not as 'nervous' as the non-powered steering of 
the 50s. As the power steering is one of the many factors adding to vehicle 
weight, the cars from this period are also less economical than the 
generation before.

2000-2009 - front-wheel drive, average weight about 1.25 tonnes (a Golf 
weighs about 1400 kg), tyre width about 7.5 inches, electric power steering, 
about 2-3 turns lock to lock, but no sensation of being actually connected 
to the wheels whatsoever.

Vehicle weights now so high that manufacturers are coming under heavy 
pressure from the environmental lobby and the EU to reduce them (and so 
reduce fuel consumption), and so are looking for ways to achieve this. One 
way is to replace the hydraulic power steering with electric. This reduces 
the drag on the engine (is it not belt driven) and also reduces weight, but 
offers nowhere near the quality of steering feel. The gearing can at least 
be kept satisfactorily high, so a typical 2009 vehicle has high-geared and 
extremely light steering which gives no sensation whatsoever of contact with 
the road.

So we have made our cars massively heavy (which makes them worse to drive 
and less economical) and then sought to alleviate this slightly by saving a 
few kg by fitting electric steering, which makes them even worse to drive 
but gives a minute improvement in fuel consumption.

And that, ladies and gentlemen, is why steering nowadays is considerably 
worse than 10, 40 or 50 years ago (but only a bit worse than 20 and 30 years 
ago). I am not making it up - it is an uncontroversial statement and easily 
demonstrated, and the reasons lie in the design priorities forced on the 
manufacturers.

It is just that we have got those design priorities all wrong...

Cheers

Al