Steering…arguably one of the most important inputs for our receiving apparatus, it is what we use to guide the car into the direction we want it to go.
From our hands outwards, force is put on the steering wheel to make it turn. That movement is transmitted down a shaft into a steering rack, where at the end of the shaft sits a small gear called a pinion. That pinion moves a shaft horizontally when it is turned over a set of teeth on that shaft (think of the shaft as a gear sliced through and pulled straight) At the ends of that shaft sit arms that are connected to the uprights pulling them in or out, forcing them turn about a (mostly) vertical axis. Because the wheel is mounted to that upright it enables the tire to enact a force on the road making the car change direction.
Phew……..anybody still there?
As you can see there are a lot of connections, and as in electronics, every connection is an opportunity to lose information.
where do we lose information?
Most of the information gets lost through either damping, or interruption of the information pathway (aka play).
Dependant on the type of car more or less damping might have been applied by the manufacturer in an effort to insulate the cabin from Noise Vibration and Harshness (NVH). This usually happens in the form of strategically placed rubber on mounting points. How do we find these devious rubber bits that stand between us and ‘perfect’ feeling? Start with doing a thorough inspection of the whole steering system. Look at how it is mounted, is any rubber used, can it be replaced?
Aftermarket manufactureres like powerflex, Strongflex etc probably make what you need(like a harder rubber/silicone, or maybe even solid mounted). Downside of course is that this increase comes with an increase in the dreaded NVH, it’s up to you how much you are prepared to live with.
This is why in a Bentley you won’t feel the wheels running over the road through the steering wheel, while in a racing car you can actually feel the stripes painted on the road surface! Most cars are somewhere in between, with the sportier cars moving closer to racing cars with increasing sportiness.
So where does play come into play?
Well, if you are like most of us mortals, the car you bought has a few years of use under its belt. If you were lucky enough to have the car from new and kept it for long enough, you might have noticed a gradual degradation of steering ‘feel’. As with anything mechanical, with use (abuse?) comes wear and tear, tolerances grow larger and the whole car feels less ‘tight’ What can we do to improve the situation (if required)? quite simple really, is there any play in the components, if yes….replace said components. You’ll notice a difference immediately! The car will drive like new with just the replacement of worn components,
Are there other ways to increase ‘feel’? Yes!, of course there are, these involve adjusting the geometry of the front suspension.
How? You ask
There are two ways that I know of, some cars come with this adjustability from the factory, otherwise most can be adjusted with the help of some aftermarket parts. The first method is increasing KingPin Inclination (KPI)…….
Wtf is KPI?
If you look at the front of the car and draw a line through the upper steering joint and the lower steering joint the angle between that line and a perfectly horizontal line is the KPI.
As you can see from this picture, increasing KPI does another thing aswell, it increases camber (which is a good thing for handling), it increases steeringfeel and gives better selfcentering.
Another adjustment is caster, (and before you ask).
Caster is the angle of a line drawn between the top steering joint and the lower steering joint when viewed from the side and a perfect vertical.
As you can see caster does nothing with camber in the straight ahead position but only changes camber when the wheel is turned, increasing it on the outside wheel. Increasing caster sharpens turn in and increases steering feel.
So why not increase both angles to the max, and your life will be better?
As a car is a complex system any change made in one part might have an effect somewhere else, too much of a change can have a negative effect somewhere else and on what you are trying to achieve. Too much caster will increase steering effort, and with wide tyres might actually decrease grip as you’re trying to force the tire onto it’s outer edge, the same goes for KPI.
Wow…for a short post this turned into a bit of a long one.
I’m going to add a section for longreads so the blog section can be more of a blog But I hoped you enjoyed it.