Corrugations mean keeping your 4X4 and yourself in one piece is not always easy.
I LOVE TOURING this country and exploring the many attractions that are available and there’s little doubt that all 4WD enthusiasts like me really look forward to the challenges on offer. It’s the ever changing terrain, tracks and environment that excites me and just the thrill of being out there.
When travelling, you’ll experience all sorts of topography, some quite enjoyable and some no so, just to reach your destination. That’s the nature of the beast but there is one travel experience that most tourers will eventually come across, and one I don’t particular enjoy – that’s corrugations.
If you do a lot of long distance touring off the tarmac and even while travelling not so remote tracks in your 4WD, it’s inevitable you’ll come across corrugations and often there is little you can do to avoid them. There are however, a few suggestions to ensure your 4WD and passengers survive the unending pounding that can come with corrugations. It’s interesting to note that you do not need to travel far from the main city to come across corrugations but they’re more common on the longer stretches of tracks in the outback.
What are Corrugations?
Corrugations are continual ripples found on the surface of tracks generally but not always at right angles to the direction of your travel. They can occur on all sorts of tracks, though the consensus and my experience is that they are more pronounced on tracks of a granular formation such as sand, gravel and gibbers though they can occasionally occur on muddy clay based tracks too. They come in several forms and can last (annoy you more likely) for a just a few meters to many hundreds of kilometres and they can be found in many places throughout the Australian country.
There have many theories thrown around the campfire on what causes corrugations but to get to the nitty gritty you’ll find several scientific papers justifying that wheeled vehicular traffic at speed to be the main cause of corrugations. These results explain along with vehicular traffic, the manner at which the vehicle is driven and the speed at which the tracks are travelled at while the tracks are dry are the main culprits on how corrugation are created.
From my experience I believe there is also some impact from the effects of weather, such as rain and wind as water run off across a sloping track can certainly instigate corrugations as tyres hit these small divots and expel loose material. Of course the impact can last well after and can range from being just a small annoyance all the way to experiencing an extremely uncomfortable ride, shaking things loose on your 4WD to the worst case scenario of damage to a 4WD’s chassis. Whatever it is, there are some things you can do to ensure you and your 4WD not only survive but do so as comfortably as possible in safety.
Preparing for corrugations
If you’re to be a serious outback tourer and wish to travel beyond the blacktop and especially if you’re loaded up, the stock suspension generally won’t cope with the pounding of outback corrugations, washouts and the inevitable erosion of dirt roads over a longer period.
It’s the continual and irregular bouncing of the tyres and rapid movement of the suspension that reverberates throughout the rest of the vehicle which can cause an uncomfortable ride, possible component failure or impact on your safety.
The stock suspension supplied with most vehicles is a compromise on comfort, ride, handling and performance at an acceptable cost. My first few suggestions for any 4WD owner wishing to drive remote areas and wishing to improve the ride, handling but more importantly elevate safety while travelling corrugations (or any tracks for that matter) is to review the 4WD’s suspension and tyres. One of the more common suspension component failures (or let-down) on corrugation are the shock absorbers if left stock or are old. The management of the up and down movement of a 4WD is controlled by the shock absorber and subsequently will generate a lot of heat when confronted with corrugations. Even more so on lengthy stretches of bad corrugations. While most quality aftermarket shocks do a better job, inferior shocks can reach a point where they get shock-fade through boiling of the oil or aeration and are unable to cope.
Over the years, industry leading manufacturers have developed solutions to address this problem of contending with severe corrugations and really bad tracks with the introduction of remote reservoir shocks. These shocks better help dispel the heat while also increasing shock travel lengths. Some of the better (more expensive) shocks are adjustable, enabling you to virtually dial in to fine tune the performance to suit your requirements.
So consider upgrading your suspension to a set-up specifically designed for your particular 4WD, taking into consideration any anticipated added weight, ancillary equipment that you may have added, intended destinations and distances you may travel. Speak with several reputable aftermarket retailers that are familiar with your 4WD and explain your intentions. Research the many online 4WD forums and groups to see what works well or not so well, so you get a better insight of real world experiences.
Some 4WD specialists may offer just one solution while others could have several options that may suit depending on budget but this is one area that really deserves money to be well spent.
If towing a camper or van is your thing, before shelling out the hard earned dollars, consult with the manufacturer to ensure that their product is not only capable of handling rough tracks and corrugations but that their warranty will cover any unforeseen breakage in such circumstances. If they hum-and-ha or cannot provide written supported documentation, then best seek an alternative product.
As a side note, while there may be some geographic restrictions, I highly recommend to take out the appropriate road side assistance for your circumstances that includes full vehicle recovery as it could be a very expensive exercise if your break down. Make sure that the level of cover includes trailers too. Unfortunately, the country is littered with garden variety box trailers that weren’t up to the task, so discuss this with your 4WD specialist too.
Improving your 4WD suspension is not a simple task of just installing a set of heavy duty springs and shock absorbers. While these are certainly major components, take into consideration your entire suspension system. Some other components needing particular attention and possible replacement, (especially on older 4WDs) are the control arms, suspension mounts and the numerous suspension bushes (rubber bushes offer less noise and more absorption of vibrations over polyurethane style bushes). Ensure the entire steering system is up to scratch and most importantly that your brake system is working as it should. Exam your entire steering system for excessive play, paying particular attention to the ball-joints, tie-rod ends and all the other components found on your particular 4WD.
If you are hands-on (or ask your 4WD specialist) take the time to go over all the nuts and bolts that hold your entire undercarriage with a torque wrench to ensure everything is torqued to specification. It’s quite easy to access the recommended specification for most 4WDs via on-line sources or work shop manuals.
A valuable technique I learnt to aid visual inspection, once you’re happy that all the bolts/nuts are set correctly is to use a white marker on all bolts and nuts. It’s a quick and easy reference to see if things have loosened over time.
Like the standard suspension that could do with attention, don’t forget the tyres. Outback roads, especially those containing corrugations made up of gibber and gravel are very hard on tyres. Road based tyres (also known as highway tyres) are generally fitted standard with most 4WDs off the show room floor. These are known as passenger style tyres. They are made of a softer compound and supple flexible side walls so that they can offer a comfortable on-road experience. But this compromises their longevity when it comes to contending with rougher roads, which can result in excessive chipping and possible destruction of the tyre.
I suggest that along with improving the suspension a set of all-terrain or mud terrain tyres be considered with a LT (light truck) construction. LT tyres offer stronger carcasses, deeper tread and an overall tougher construction to contend with the toughest of tracks. I’ve driven my Jeep with all-terrain as well as mud tyres and while the all-terrain tyres performed faultlessly, I think the muddies gave a slightly better ride over corrugation. I put this down to the larger rubber chunks being better at absorbing the irregularities of the track than the all-terrains.
Securing it all down:
Even though you may have addressed your suspension and tyres as well as having adopting a good maintenance regime, corrugations can still be very hard on your 4WD, passengers, ancillary equipment and everything inside.
Make sure all your cargo and contents are secured properly by using ratchet style straps and avoid the use of bungee style cords as they’re just too inflexible and don’t offer a tight fit. Even slight movement on a corrugated road can result in things wearing through or worse – breakage of cargo or 4WD interior fittings. I found carrying several smaller sealed packing cases and utilising rags, towels or even clothes helps to make sure contents are snug and protected against the ongoing jarring from corrugations.
If you’ve got a roof rack ensure the roof rack mounts are tight and don’t move. Having a roof rack will raise the centre of gravity of your 4WD. It’s bad enough that that a loaded roof rack will have a huge impact on stability, so it’s important that you ensure the safekeeping of items held up there. Confirm that any driving lights, UHF aerials and the spare wheel are all properly secured. If I suspect that something may be compromised due to overly rough roads, I use light-medium strength Loctite or similar to help prevent bolts loosening at the worst time.
On the Corrugations:
Once you’ve set up your suspension right, have a set of good tyres and secured all that needs securing then the only other advantage remaining to contend with corrugations is to adjust the tyre pressures of your 4WD and to adapt your driving style to the conditions.
Lowering your tyre pressures will result in several advantages and improvements. Think of your tyres as working hand-in-hand with your suspension. Properly adjusted tyre pressures along with your suspension will further help absorb some of the impact from the corrugations. With lower pressures, the tyres will provide a further cushioning effect and will improve the ride as well as traction. Lower tyre pressures have the extra benefit of protecting the tyres from sharp rocks and gibbers commonly found along with corrugations as they mould over the sharp obstacles. Really very important if your 4WD is fitted with lower profile tyres, like commonly found on many late model 4WDs and SUVs. On tracks with sandy corrugations lowering pressures increases your foot print and provides better traction, especially beneficial when you come across curves on corrugated roads.
Remember to adjust (read lower) your speed as handling and braking can be compromised when driving corrugations and at lower tyre pressures. There will be occasions when it’s safe to increase speed. Remember to gradually wipe off speed well before approaching dips or curves in the road as understeer will be more prevalent. Consider selecting 4WD high range or the appropriate terrain response option if fitted, to deliver you maximum control and safety.
It’s difficult to give an exact figure when it comes to tyre pressures as it depends on many factors including but not limited to the model of 4WD, 4WD weight, driver experience, track type/conditions or the severity of the corrugations. I suggest commencing around 26-32PSI or about 75% of your normal road pressures. Along with the lower pressures, you’ll need to lower the speed. Generally, when I travelled corrugations I’d never exceed 80km/h and often on really bad stretches I’d be travelling around 20-30km/h. To be honest, I’d rarely looked at the speedo as I was concentrating more on the road ahead and travelled at a speed that felt right for the circumstances. Naturally you’ll need to play around to secure the ideal ride, comfort while factoring safety for you and your vehicle.
During your Travels:
Whenever you travel it’s imperative to carry and use the best equipment that you can afford. This is even more important when travelling remote regions that can dish up all sorts of challenges such as travelling long stretches of corrugations.
Besides carrying all the usual recovery equipment and tools and knowing how to use them, when it comes to corrugations I carry a couple of analogue tyre pressure gauge (they are very sensitive and prone to failure if you knock or drop them, that’s why I carry a few). They’ll set you back well under $20 for a good and easy to read one. You’ll also need a means of deflating and re-inflating tyres to your preferred pressures. I suggest a purpose built tyre deflator for around $30 or carry a 4-way tyre valve repair tool for just a few dollars. It’s quite common that you could end up doing this multiple times throughout your travels. So don’t be lazy and do regular checks after lengthy stints behind the wheel or when conditions dramatically change. It will give you the best results. Remember to re-inflate to road pressures once you’re back on to hard surfaces and don’t skimp on buying a quality air compressor with ample hose to reach all parts of your rig.
Talking of regular checking, as mentioned, corrugated road can range from just a mild pain in the back side to corrugations that make your teeth chatter. So besides caring for your 4WD, it’s imperative that you take regular stops or swap drivers to give you a rest (corrugations can be just as hard on your passengers). It’s also wise to take the opportunity to perform a quick visual around your 4WD and it’s under carriage, looking for fluid leaks or overly shiny metal near joints that are a sure sign of loose components. Lastly give your wheel lugs a quick wrench to ensure they are nice and tight but not overly. For my alloy wheels on my Jeep Wrangler JKU, I set them at around 128 Nm–135 Nm (95-100 lbf).
I hope that knowing these hints will make life a lot easier when tackling those infuriating corrugations on your next adventure.
