Now how did that happen?
Ha ha … nothing against the lovely people from Australia. I was referring to the memes where going Australian implies that you are upside down. In this post, I will be discussing how to keep your 4×4 SUV from rolling or flipping over on different kinds of terrain.
Image Credit: MEANWHILE
Different types of terrain
In general, we can differentiate between three types of terrain – tar, off the tar but accessible to most vehicles e.g. gravel road and then offroad terrains such as mud, obstacles and sand.
Tar road: Accessible to all roadworthy vehicles
Image Credit: Tar Paving – The Best Tar Surfacing Roads services!
Gravel road: Accessible to most vehicles
Image Credit: Grading Gravel Roads: Motor Grader Adaptations
Offroad track: Only capable offroad vehicles need to apply
Long or short wheelbase SUV
We are specifically talking about offroad capable SUV’s here such as the Jeep Sahara or Rubicon and pre-2017 Land Rover Defenders. Vehicles with low range, solid axles and some sort of difflock configuration. Please don’t roast me slowly over hot coals, I know that there are many more examples of capable SUV’s, but I am sticking here to what is most familiar to me.
The important thing to keep in mind is that a long wheelbase is inherently more stable than a short wheelbase. Personally, I prefer a short wheelbase because it is more manoeuvrable but I have to adjust my driving style to compensate for an increased risk of rollover.
How not to flip over on tar
You have to accept that an SUV with solid axles is not going to perform around the corners like a sports car.
When you look at the Megane cornering around the track below, you will notice a few things:
- The tyre profiles are low to minimize sidewall flex. This increases grip on the tar.
- The chassis is low to the ground, contributing to a low centre point of gravity.
- The stiff racing suspension allows for minimum body roll around the corner.
All of these factors contribute to stability around corners at speed and therefore the car can safely do this (within reason). The vehicle is designed in a way to prevent rollover around corners.
Megane RS around the track
Image Credit: Renault Megane R.S. review: Sport to Trophy-R driven
Now consider the Jeep below. It has a suspension lift and bigger tyres.
- The tyre sidewalls can flex to accommodate deflation in offroad conditions.
- The chassis is high off the ground as the increased clearance decreases the chance of damage due to rocks or other obstacles.
- The suspension is flexible to maximize wheel articulation. It is a great advantage to a vehicle if all the wheels remain in contact with the ground at all times as it increases traction.
Jeep flexing its muscles
Can you see the two vehicles are on opposite sides of the spectrum as far as these points are concerned? The Jeep is going to experience a lot more body roll around corners and therefore it is much more likely to flip if you corner at high speed.
The key is to brake BEFORE the corner to reduce your speed to a safe level. Braking in the corner can increase body roll and should therefore be avoided. The second thing to keep in mind is that the Jeep is not designed to drive at the same speed as the Megane.
You may be able to (illegally) do 160km/h in the Megane and not necessarily put yourself at risk. The Megane can steer and brake properly at those speeds. Not so with the Jeep. The SUV can reach 160km/h or faster but then you better pray that you don’t have to swerve or do an emergency brake in the near future. The chances of exiting the tar in a most unpleasant and catastrophic way are simply too big. I would go as far as to say that the Megane is safer at 160km/h than the Jeep at 120km/h.
So the key is to drive slower in the SUV. With its brick-like aerodynamics, you will also thank me with all the fuel that you are going to save.
Another phenomenon to look out for with solid-axle SUV’s is steering wobble. If you hit a bump in the road or a pothole at speed, you will have a tough time keeping the steering wheel steady. For quite a distance afterwards, you will be riding rodeo.
Again, brake well in advance when you see something in the road ahead.
How not to flip over on gravel
Your SUV was designed for offroad driving, right? Your Jeep will make mincemeat of a level gravel road, right?
Hold on, not so fast.
Especially if you are driving a short wheelbase SUV, you really need to pay attention if you don’t want to see your rear end drive out in front of you.
When I enter a gravel road, I always engage the centre difflock on my Defender as a precaution. Remember, even though an SUV may be all-wheel drive, it doesn’t mean that much if one of the tyres lose grip. Let’s say one of your tyres hit an unexpected loose sandy patch on the gravel and you are driving at high speed. That tyre is going to spin and all drive will be sent to it if the axle is open. That means that all the other tyres are going to lose drive and traction for a moment. The same principle as when you are going around a corner and you suddenly take your foot off the gas.
The force of motion will make you want to go in a straight line – that means off the road and taking a tumble. And I’ve seen dashcam footage of this happening very quickly – Toyota Landcruiser doing 80km/h on gravel and then flipping in less than a second after hitting a patch of sand.
The moral of the story is to take gravel slow and easy and engage difflock (if you have it – the Sahara has traction control) if the gravel is loose. If the gravel is highly compacted and almost resembles tar, you don’t want to do this as you are likely to break something in the drivetrain.
I am not going to cover trail driving here. If you are interested, I have written a short blog post on offroad tips and techniques that covers a few of the basics.
Hope that you found all of this informative and that your worldview remains right side up.