18 minute read
TECHNICAL REVIEW SERIES PART 2 ON SOFT ROADERS: MOD TO MAKE A
Article by Daniel Ho
Advertisement
Typically, a 4x4 enthusiast will consider making the following modifications to their vehicle, to improve the vehicle’s off-road and touring capabilities. 1. Underbody protection 2. Recovery points 3. Tyres and wheels 4. Car mounted UHF Radio
5. Throttle controller
6. Roof carriage system 7. Lift kit
8. Bull bar
9. Snorkel
10.Differential and transmission breathers
11.Suspension and brakes upgrade 12.Differential lockers
13.Lights (Spotlights, a light bar, etc.) 14.Winch
15. Solar / Dual battery system
Recovery points
Very few 4x4 come factory equipped with proper off-road recovery points. Traditional “old school” 4x4s are built using the “Body-OnFrame” design, where the cabin body of the vehicle is placed over a chassis rail frame. Modern vehicles have adopted the unibody design where the entire body of the vehicle is part of the load carrying structure. Unibody vehicles have better road handling and are typically safer due to the intricate crumble zones designed into the frontal structures. This makes installation of rated front recovery points more problematic.
Here we’ll examine which of the above are available for Subarus.
Underbody Protection
Underbody protection such as bash plates for the engine sump and the transmission oil pan are extremely important. The oil pans of both the engine and the transmission are extremely vulnerable to punctures from impacts when offroading. While some 4x4s, including the new Subaru Wilderness range, come equipped with factory fitted underbody protection, they tend to be light weight protection plates and owners who take their vehicles on proper off-road adventures usually upgrade to proper heavy duty protection plates.
In Australia, there are two main suppliers of bash plates for Subarus, being Road-LessTravelled (run by David Wilson, a S4WDVic Club member) and SubaXtreme in NSW. Guards are available for all models of Subaru vehicles, both for the engine sump and transmission oil pans.
The easiest way to incorporate a recovery point to the rear of the vehicle is by installing a tow bar that is compatible with a hitch recovery point (as depicted below). They are available from most 4x4 accessory outlets and simply slot into the square hitch of the tow bar.
Having suitable recovery points is extremely important when off-roading, as they provide secured points for recovery straps or winch cables to attach to, allowing a stuck vehicle to be pulled out without causing damage to the vehicle.
To the matter of front recovery points. As mentioned above, it is difficult to install front recovery points to unibody vehicles due to the safety engineering on the vehicle structure. Notable modern 4x4s that are of an unibody design include • Land Rover Discovery 5 (2017-present) • Land Rover Defender (2020-present) • Mitsubishi Pajero (1991-2021) While the unibody approach is still in the minority within the full size 4x4 segment, all vehicles in the SUVs and cross-over segment are unibody designs. Tradition “Body-On-Frame” vehicles can be fitted with aftermarket rated recovery points that are simply bolted onto the chassis rails.
Ironman 4x4 (recovery points for the Ford Ranger) - Subaru Ascent’s points are bolted onto the unibody with two rated bolts (same as how off-road rated recovery points are attached) - Some models of Foresters and Outbacks have points that are similar to those on the
XV, while others have points that are metal hoops spot welded onto the vehicle So what are your options as a Subaru owner? There are several
1) Rely on the factory tie down points, but use a suitable length kinetic rope bridle when being recovered from the front 2) Invest in the rated recovery system recently released by SubaXtreme 3) Invest in a custom engineered option The vast majority of Subaru owners opt for Option (1). Options (2) & (3) both have significant Pros and Cons and should be carefully considered before committing.
This option is not available for unibody vehicles. One question that is often asked, is whether the front tie-down points on an unibody vehicle can be used as recovery points? The answer is that “it depends”. For example, while not specified in their publicity material, Mitsubishi officially confirmed to the Pajero 4WD Club of Victoria that the front tie-down points on the Pajero are in fact rated for off-road snatch recovery. This is also the case for the Land Rover Discovery and Defender. HOWEVER, not all tie-down points on all vehicles are made to the same engineering standard. Subaru has not provided its customers with similar confirmation regarding the strength of the tie-down points on Subaru vehicles. It should also be noted that the tiedown points differ in design between different model and year of Subaru vehicles. For example, the tie-down points in a - 2014 Subaru XV are an integral part of the unibody structure
Third on the list of modifications is tyres and wheels. Driving off-road involves driving on low traction surfaces such as mud, gravel, dirt, as well as exposing the tyres to sharp objects and impacts. Consequently, it is essential to upgrade the tyres to off-road tyres that are designed for use away from tarmac surfaces. Off-road tyres, be it All-Terrain (AT) or MudTerrain (MT), are made to provide better grip on loose surfaces, with better puncture protection, and reinforced sidewalls for use with low tyre pressures.
Smaller diameter wheel rims allows tyres with higher side wall heights to be used. High sidewall tyres provide improved off-road performance as well as protect the wheel rims from impact damage.
There is a reasonable range of tyre options for Subarus. Below are some manufacturers that make tyres in sizes that fit unmodified Foresters, Outbacks, and XVs. • AT Tyres: BF Goodridge, Toyo, Pirelli,
Hankook, Yokohama, Falken • MT Tyres: BF Goodridge, Hankook
With wheel rims, the early Forester models were factory fitted with 15” rims. Later models of Foresters, Outbacks, and XVs were equipped with 16” and 17” rims, with more recent models equipped with 18” rims. For most Subaru models, reducing one wheel rim size (i.e. from 17” to 16”) would not result in clearance issues between the brake calliper and the inside of the rim. However, reducing two rim sizes typically requires the use of specialised wheel rims. It is best to consult other Members of the club as well as check with your trusted tyre shop on options (note that not many tyre shops understand 4x4 setups and have knowledge of Subarus).
Beadlocked wheel rim options are also available for Subarus. However, beware that most beadlocked wheel rims are technically permitted for off-road use only. Why the need for a car mounted UHF radio? Can’t I just use my handheld radio?
The main reason for installing a car mounted UHF radio is their effective communication range, which is a function of the power output of the radio and the attached antenna. The second reason for having a car mounted UHF radio is the ease of use.
A car mounted radio typically has a maximum power output of 5W, whereas handheld units are typically between 1-2W. The effectiveness of an antenna largely depends on the height from the ground as well as the presence of RF barriers surrounding the antenna. Simply put, a car mounted UHF radio typically has a higher power output than a handheld one, while using an antenna that is likely to be mounted higher off the ground and away from RF barriers. A well positioned car mounted radio is also easier to access while driving, with communications being easy to hear over the noises inside the car.
The considerations and installation of a UHF radio in a Subaru are the same as that to a full size 4x4. You local 4WD accessories retailer should be able to assist you in choosing the right radio for you.
Electronic throttle controllers are a modification that can be done to modern vehicles with electronic throttles rather than use physical throttle cables. An electronic throttle is where the throttle pedal in the car is connected to an electronic sensor. The sensor detects the amount the throttle pedal has been depressed and sends a signal to the ECU, which in turns adjusts the degree to which the engine throttle body opens. This dictates the amount of air that flows into the engine. An electronic throttle controller is a device that modifies the relationship between the amount of movement in the accelerator pedal, and the signal sent to the ECU.
Roof Carriage Systems
Invariably, at some stage one would need to consider a roof carriage system for carrying items such as shovels and recovery boards, spare tire, or a rooftop tent. There are numerous options, and the considerations are the same for full size 4x4s and Subarus alike, being • Roof / roof rails load rating • Type and size of the roof tray G8 Racing Throttle Controller • Ease of loading and unloading
Lift Kits
The chart above is a simple illustration on how an electronic throttle controller changes the response between the accelerator pedal position and the operation of the engine throttle body (100% output = fully opened throttle). Depending on the model and year of the Subaru, there may be one or two lift kit options. Subaru Lift Oz (SLO) makes lift kits to fit Forester, Outback, and XV Subaru vehicles; Road-Less-Travelled makes lift kits for L-Series; and Ironman 4x4 makes lifted replacement struts Subaru vehicles using the new Global Platform. Several US companies also provide lift kits for Subarus
Almost every model of Subaru vehicle can be lifted.
All electronic throttle controllers work on the same principle. The difference is that they use different proprietary response curves, and some have more options than others.
Changing the throttle response to the pedal enhances the amount of control one has over the vehicle. For example, when driving on rocky technical terrine the ability to exert fine degrees of throttle control is an advantage. Conversely, a quick throttle response is preferred when driving on soft sand. A throttle controller allows the driver to pick the desired throttle response base on the nature of the terrain. found in the Australian market are - Ultimate 9 EVC (iDrive) - HikeIt x5 & HikeIt X9 - SAAS S-Drive
Generally speaking, Subarus equipped with Electronic Stability Control (ESC) systems can be legally lifted by 50mm without the need for additional engineering certifications to be done. Earlier vehicles without ESC can be lifted by 75mm without additional engineering certifications. However, please check the legislations that apply specific to your vehicle’s model before installing a lift as there are also differences in legislations between different States.
VSB-14 is a good place to start your research.
• SubaXtreme (Goulburn, NSW, 2580)
• East Coast Bullbars (Clontarf, QLD, 4019)
• Irvin Bullbars (Midvale, WA, 6056)
Each of these bars have their own Pros and Cons as they are made differently and mount onto the vehicle differently. Consequently, they differ on their impacts on approach angle and durability. The choice of which company’s bullbar to use is very much a personal preference and is highly dependent on the reason on one’s requirements. Bullbars also offer additional real-estate for mounting of lights, radio antennas, and sand flags. In general • Irvin Bullbars’s products are of designs akin to those on trucks that drive on Outback highways and arguably offer better protection against minor impacts with wildlife • ECB’s bullbars are of a fit over design, which are easier to install and do not require irreversible modifications to the vehicle’s bodywork. • SubaXtreme’s bullbars are made from a light alloy with shapes that are more in-line with 4x4 bars designed for off-road use.
Andrew Westerland, QLD
www.subaruoutback.org
(subaruforester.org) “denzzkyy” uzhno-Sakhalinsk, Russia
Snorkels
This is a trickier modification to implement than the other mods for Subarus, as there is no commercial off-the-shelf system available. This is not to say that it cannot be done, as there are plenty of road legal Subarus fitted with Snorkels.
The traditional favourite for Forester owners is to use the external snorkel designed for the Mitsubishi Pajero Gen II, as the shape of this snorkel design conforms well to the Forester. More recently, Forester owners have found that snorkels designed for the Mitsubishi Triton to be a closer fit. For a snug fit, typically some heating (with a heat gun) and slight bending of the snorkel is needed.
Obviously, the custom built option is always possible and is the only option if one wants a snorkel that is a perfect fit. The reason for having a snorkel is to enable crossing of deep water without running the risk of flooding the engine. Therefore, it is crucial for the rest of the air intake system it also be watertight. This invariably requires modifications to the air filter box.
• Option 2 is to use an air filter box from a different vehicle, but one that fits neatly into the space available in the engine bay without needing much modifications. • Option 3 is to use an in-line air filter box and a
POD air filter.
• Option 4 is to have a custom air filter box made.
Which of these four options is the most suitable for you will depend on your budget, the “look” you wish to achieve, and the performance functions you desire from the system.
Option 1
1) The existing hole in the factory air intake box needs to be sealed. This can be done by using a soldering iron with a flat tip to plastic weld a piece of plastic over the hole; 2) Replace the air filter with an aftermarket air filter element that has a rubber seal around the edges. One such option is the reusable filters from BMC. 3) Create a new access hole at the bottom of the factory air filter box for the snorkel.
Option 2
The following air filter boxes from Toyota fit into the Subaru engine bay without much modifications required. These air filter boxes are already sealed units and do not require the use of “special” air filters. The snorkel connects directly into the intake port of the replacement air filter box. • Toyota Lite Ace 3CT air filter box (into a Forester) • Toyota Hilux 2.7L Petrol Engine, 19972004 model (into a XV)
Option 3
Companies such as SAAS and K&N make in-line housings for use with pod air filters. These can be used in-lieu of the factory air filter box and connect directly into the snorkel piping.
Option 4
Custom made air filter boxes are not uncommon in heavily modified 4x4. Cost aside, there are no impedements for similar units to be made for a Subaru.
Caution
Modifications to air intake systems and mounting of external snorkels are regularted by roadworthy requirements. Please refer to the following for the relevant applicable regulations • Roadworthy requirements of a Light Vehicle in VSI 26 • Acceptable modifications that do not require a VASS Approval Certificate are contained in VSI 8 • VSI 29 for specifications surrounding the requirements for the driver’s field of view to remain clear when fitting accessories to the vehicle Information provided by VicRoads
Transmission and Differential Breathers
When it comes to crossing water and bog holes, one should also ensure the transmission and differential breathers are located sufficiently high to prevent water being sucked into them. Differential and transmission breathers are at risk of water ingestion if the oil in them is warm when the car contacts water and the breather intake is near or below the waterline. The oil and air inside the differential / transmission contracts due to cooling, creating a negative pressure that can suck in water. Fortunately, most Subarus already have elevated breathers for the front transmission and differential. They are typically located above the engine, thus are not at risk of water ingestion. However, the rear differential breather is located near the top of the rear differential and is almost always at risk of water ingestion. It is therefore necessary to route the rear differential breather to an alternative location that is sufficiently high. -40-
New air intake location in a stock XV air filter box
Toyota Hilux 2.7L Petrol Engine, 1997-2004 model air filter, installed in a XV
Example of a K&N Apollo in-line air box Example of a universal fit in-line air filter box for use with POD filters
In many 4x4, the breathers are relocated to the engine bay. However, this is a long way from where the rear differential is on a vehicle. Given for most Subarus only the rear differential breather needs to be relocated, a closer viable alternative solution is to relocate it to the chamber behind the fuel filler cover. Behind the plastic / rubber spill cover surrounding the fuel filler port is a chamber that can be used as the rear differential breather outlet.
The physical process and procedure for the relocation is the same as for all 4x4. It involves removing the cover of the rear differential and installing new barb connectors, hoses, and breather filters.
Behind this cover
Carrying heavier loads constantly on hilly terrain results in additional demands on the car’s braking system. Consequently, many owners also upgrade their brake systems. There is nothing special worth mentioning about a Subaru’s brake system, and the typical brake upgrades available to other vehicles are also available to Subarus.
Differential Lockers
While the virtues of having diff lockers deserve to be covered in a standalone article, it should be highlighted here that differential lockers are available for Subarus.
• Mechanical auto-lockers: Torq Locker • LSD: Cusco, Tomioka
• Air & E-Lockers: There are some hints that people have been able to make ARB airlocker and Eaton e-locker work in a Subaru rear differential
A rear differential locker will significantly enhance a Subaru’s off-road capabilities. On the modern models equipped with X-Mode, a rear locker transforms the Subaru into the equivalent of a twin-locked 4x4 and goes a long way to mitigate the lack of articulation issue, especially on cross-axle terrain.
Sintered breather filters
Suspension and Brakes Upgrade
When touring, because of all the equipment, food, and potentially fuel that needs to be carried, it is not uncommon for vehicles to be heavily laden. The stock suspension on most vehicles are not designed to maintain close to the vehicle’s unladen ground clearance when fully ladened. Consequently, it is not uncommon for 4x4 owners to install heavy duty suspensions into their vehicles. - King springs - KYB suspension struts - Pedders suspension (springs and struts) - Rallitek springs - Bilstein struts
Lights (Spotlights, a light bar, etc.)
While there is no doubt that additional lighting is essential for driving on remote highways and tracks at night, night off-road driving for most people is a novelty and not a regular occurrence. Nonetheless, there is nothing special about Subarus that preclude them from using aftermarket lighting systems available at common 4WD lighting shops.
For the mainstream 4x4, the most common way to install a winch is by installing a winch compatible bulbar. There current are no ADR approved winch compatible bullbars. Some Forester owners might be in luck, as SubaXtreme has purchased a design and is working towards ADR approval and manufacturing of it.
The new winch compatible bar being worked on for production by SubaXtreme
One option for Subaru owners is to use a winch cradle that sits behind the bumper bar. This approach is not unique to Subaru, with winch cradles being used in 4x4 such as the Ford Ranger, Mazda BT-50, Isuzu D-Max, Toyota Hilux, etc.
Solar and Dual Battery Systems
Dual battery systems are particularly important if one was to run additional electrical equipment such as fridges and winches in the vehicle. Several of the Club Members have installed dual battery systems on their vehicles to run onboard fridges. The same electrical equipment such as DC-DC chargers and inverters are used in Subarus as other 4x4s.
Lithium battery technologies have also improved significantly in recent years, with “drop-in” replacements now available. “Drop-in” batteries are designed to be direct replacements for existing flooded and AGM batteries without the requirements for additional charging systems to be installed. The development and availability of high-capacity drop-in battery options may eliminate the need for dual battery systems.
Behind bumper winch cradle, for the Ford Ranger and the Mazda BT-50
However, there are no manufacturers of such winch cradles for Subarus in Australia. One would need to import them from overseas. A winch adds to the vehicle’s off-road capabilities in the following manner • Ability to self recover, especially for ascending steep hills or getting out of bog holes. • Ability to rescue other bogged vehicles • Ability to pull large fallen trees off the track Subarus, being light weight vehicles, do not necessarily need heavy duty winches. The later generations of ATV winches are rated to 4500lb loads and have proved to be popular options by Subaru owners in the US. The added bonus is that these winches only weigh between 6-12kg.
Solar systems are typically used for recharging the onboard batteries and/or power fridges at camp. Solar and battery options available to other 4x4 are equally applicable for Subarus.
