Your advice on driving a bit faster (or very slowly) to iron out rough roads certainly works. But does the quicker option increase wear and tear or cause damage? Zak
Warning: There are a lot of “ifs” in this answer. After all, “Rough Roads” is a broad term, embracing anything and everything from broken tarmac to rock’n’roll cobbles, to potholes, erosion ditches, dried mud ruts, corrugations, truck-pummelled lava fields, dustbowls with humps and lumps and wallows, dirt tracks with erosion channels punctuated by large and jagged boulders…and so on.
Broadly, whatever you feel in the seat of your pants or your hands on the wheel (or hear) are messages from all the components between you and the road – the tyres, the springs, the shock absorbers, the bushes, the mountings, the joints, the bodywork, the interior trim…
What you are feeling and hearing is how much and how often every moving part has to work, and the amount of shaking all the static parts (including you) are having to suffer.
So, where the rough is moderate and consistent, if you feel less shake and bounce (and don’t hear any bangs) at a particular speed (high or low) the probability is that all the components involved are suffering less punishment, not more.
In this context, higher speed does not increase the number or size of bumps on a given stretch of road the systems have to deal with – only the frequency with which they are handled.
Indeed, it is more likely to reduce the degree of flexing to absorb the shocks, because the car is going fast enough to “skip and skim” over many of the irregularities.
And all the components are designed to cope with that – within the limits of their design! Whether they are flexing twice or five times a second is of little consequence to a steel spring, a lump of rubber, or a welded joint. What matters to them is how far they have to flex, and the force of the cause.
There are two red lines. One is when the capacity to flex reaches its limit - the bump stop – and instead of absorbing any additional shock the component is hammered by it.
The other is if the flex is well within its limits, but so short, rapid and sustained that it causes a “hot spot” of friction. This applies mostly to the shock absorber shafts, and if it is very extreme and sustained there is a danger of it reaching a temperature limit (several hundred degrees centigrade) that could cause the seal (which allows the shaft to slide without letting the oil out) to distort. At that point the oil does escape and the shock absorber fails.
So, in moderate and fairly consistent off-road conditions, higher speeds are often better for the car and its occupants. But...
...if there are occasional obstacles that the wheels cannot iron out and skim over - a single large rock or a deep, square-edged pothole - speed turns from friend to foe. Because speed is a component of power. And twice the speed not only doubles the force arithmetically - it multiplies it geometrically. The risk of damage skyrockets.
So, if moderate conditions change or include some severe surprises, whether extra speeds improve comfort and care or increase wear and risk of damage depends on the driver’s visual acuity, alertness, judgement and reflexes.
Whatever the driver’s call on those scores, the car will be the final adjudicator.
