Marks 4WD Adaptors first came up with the idea of a bolt on portal axle conversions for existing 4WD vehicles in 2002.

Now the idea was born the next thing to do was to decide which vehicle would become the first recipient.

After some deliberation the Nissan GQ Patrol was selected because of its popularity amongst the off road competition, and the serious off road driver fraternity here in Australia.

Some design criteria included:

A minimum of 100mm increase in differential height offset.

A wider wheel track for increased stability.

Retain as many of the original Nissan parts as possible.

Be fully road legal with 35" tyres. 

In 2005 the first concept Nissan portal axle was displayed at the Melbourne 4WD show. The original concept portal was designed to fit the GQ patrol front and rear ends. After talking to many 4WD competition drivers and keen 4WD enthusiasts at the show we decided that the GU Patrol having a much stronger front end would be far better suited for the conversion. Unfortunately the GU front end was quite different to the GQ model, this meant that a total redesign was required. By early July 2006 the first prototype actually turned a wheel.

Below are just a few of the photos taken while assembling the first GU prototype.

This photo shows just how may parts are involved.   Check out the input gear, all of the gears are 40mm wide. The input and output gears are supported by two 90mm roller bearings and the two idler gears are each supported on two needle bearings. The two cavities located on both sides, at the top of the main portal housing are used to provide a ventilation port which keeps the oil from exiting with the expanding air inside the housing. The portal cover is made from alloy steel. The oil in the portal transmission is separated from the wheel bearings by means of a seal fitted inside the stub axle, next to the output gear. The seal runner for this seal can be seen in the output axle in the above photo.

New disc rotors are fitted, they are all standard Nissan GU type, slotted rotors can be fitted if required. In the overall design strength and durability are paramount, the king pin bearings are beefed up by the addition of ball joint indexed into the lower king pin bearing support. The ball joint pin is secured to a strut which is fixed at the other end to the main banjo housing by four M10 high tensile bolts and two welded brackets.

The vehicle fitted was our 2004 model 3ltr turbo diesel. I drove the vehicle home and boy was I excited, a world first, portal axles specifically designed for a Nissan Patrol. The vehicle felt great from the start, it drives just like factory, except its 150mm higher and that's all under the diffs. No change in the steering and no increase in body roll. Back at the workshop next day we checked the oil levels and found them to be down a little, 15 to 20ml. Over the next few days we checked it again and added a little more. No visible oil leaks found at this stage.

The first real maiden voyage took us (Denny and I "Mark") on a 1100k, two day drive. This drive consisted mostly of road driving which took us from Melbourne through to Wagga Wagga in NSW and back to Melbourne Via Mansfield. While at Mansfield we dropped into see Alan and Barbara Johnston who own Piranha Off Road. Alan and Barb have a farm just out of town, Alan was pretty excited to see the Patrol on the road and was very keen to go for a test drive around his property. The following photos where taken on Alan's farm, this wombat hole was one of his first targets. The hole was almost as deep as the tyre was tall and the diffs didn't even touch the ground, by the way, the vehicle is fitted with standard height suspension. Alan was pretty impressed and decided to put it through a number of other obstacles to test the improvement in the approach and departure angles. All of the obstacles didn't bother it until he became so confident with its ability that he thought it could drive over a 3'/1mtr high embankment, unfortunately this wasn't going to be possible without causing a great deal of damage to the sill panels. Perhaps I should fit some rock sliders before we try that one again.

Back to the workshop for an oil level check, down a little, but not enough to worry about. It was thought that the sealed transmission bearings may be taking in a little.

Now to add a few bits a pieces before the next test run.

In went the Outback Interiors drawer system, cargo barrier, 60ltr water tank an Engle 40ltr fridge, and long range fuel tank.

Aaron built a new bull bar, and on went a winch, dual battery system, driving lights, and the usual HF, UHF, and GPS antennas.

  Back on the wheels again ready to go bush. The rims in this photo are steel and have a positive 25mm offset.

Time for some more serious testing, one aspect was oil temperature. This was considered to be of great importance as the portals contain a fairly small amount of oil when compared to a differential or transfer case. Some of the testing took place during sustained highway driving with the vehicle fully laden. More testing on rough corrugated roads and while tackling steep sand dunes was also thought to be required.  

Earlier on in the year we had planned giving the portals a good shake down as soon as they were completed. Denny and I got together with friends of ours Anthony (Ant) Kilner and his partner Jane to plan the portals first endurance test trip. Ant has a website for his business which is www.antefiction.com.au He has many amazing photos including outback scenery, competition and modified vehicles.

This trip of approximately 6000km, took us from Melbourne to Coober Peedy via Mildura, and Port Augusta. From Coober Peedy west along the Anne Beadell Highway to Vokes Hill and then south to the Nullarbor Road House on the Eyre Highway. Then across to Ceduna and north via Googs Track to follow the Trans Continental Railway line back to Glendambo on the Stuart Highway. From their we travelled back home via Port Augusta and Mildura.

A fantastic sunrise on the east side of Renmark, one day from home. Lake Hart just of the Stuart Highway South Australia.

The Breakaways just north of Coober Peedy. Westward bound the start of the Anne Beadell Highway just out of Coober Peedy. This road had plenty of corrugations, along here we periodically checked the oil temperature, the portals measured 44 to 48 degrees C while the diff measured 48 to 52 degrees C. These measurements were taken using an infrared thermometer.

Some damp spots after recent rain. This seamed like an unlikely spot for a give way sign, heading south from Vokes Hill.

On the Nullarbor Plain just north of the Nullarbor Road House. Nullarbor Road House for some fuel and a much needed shower. We set up camp out behind the road house, at this point we had travelled around 3000klm since we had left home so I decided to check the portal oil levels, all were fine except the front left hand side which was down about 50ml.

Our first camp site on Googs Lake. On the shore of Googs Lake. Sunrise at Googs Lake.

Heading north along Googs Track. This track has many sand dunes which have been compared to the sand dunes of the Simpson desert. Mount Finke in the back ground.

While at Mt Finke I did the usual look around the vehicle to make sure nothing was going fall off. Good thing I did as the front right hand side free wheeling hub had decided come loose. Fortunately for me none of the socket head cap screws had been lost. The had all worked their way out with almost a 3mm gap between the wheel hub and the free wheel hub. From then on I checked all of the socket head cap screws whenever we stoped.

  We were the first 4wd's to travel this section of new track, it was completed the day before.

Crossing the Trans Continental Rail Way Line. From here we headed home via Glendambo, Port Augusta and Mildura.

In the following 3 weeks the portals had clocked up a total of over 10,000km in the Nissan.

It was now time to strip them down for an inspection and find out why the oil level was changing. Internally everything looked perfect, no apparent wear to any of the bearings, shafts or gears.

The oil level fluctuation problem in the rear was found to be due to the sealed bearings used on the input and output gears. When filling the portals the seals prevented the oil from entering the pockets between the housing and the back of the bearing. It was found that after driving the vehicle some distance the oil would eventually fill the pockets, thus lowering the oil level. To overcome the problem we machined some oil ways around the bearings allowing the oil to flow freely behind the bearings.

When the front portals where striped we found that the seal used on the input gear to prevent oil from entering the swivel housing was damaged, the seal lip had been partially turned inside out. This was the case for both sides on the front end. The reason for this was due to poor seal design, the seal lip had no chamfer which caused it to be caught by the seal runner on the gear, during installation. Even though the gear is machined with a 2.5mm chamfer and the seal being well lubricated we where unable to install the gear without turning the lip inside out. New seals with a suitable chamfer were sourced and tested with 100% success.

The free wheel hub which came loose was addressed by manufacturing some special studs made from high tensile steel.  The new studs are used on both the front free wheel hubs and the rear axle drive flanges. The new studs are machined with a shank having a very close tolerance in the drive flange and free wheel hub, bolt holes. The studs are M10 and when fitted, loctite is applied to the thread on the wheel hub side to prevent them from coming loose. The rear drive flanges and free wheel hubs are such a close fit that they need to be gently taped onto the studs using a soft hammer. They are then secured using nuts and spring washers.

The next 4WD trip was into the Victorian high country via Licola. Our destination was some of the tracks around Mt Skene such as the Barkly River Jeep Track. We headed to Licola Friday night with Danielle and Aaron in the Bundy. On the way we stoped of to see some friends, Rom and Liz who live near Glengarry just north of Traralgon. Saturday morning we headed of, up the Licola Jameson road to the Barkly River Jeep Track.

We headed north along the Australian Alps Track over Mt Mc Kinty, the rock outcrop below stopped the Bundy in its tracks. With front and rear lockers in, the Bundy was unable to scramble over this one, instead the front diff locked itself on to this rock, well and truly. Danielle wasn't able to go backward or forward, the winch was the only way she could get it moving.

The Portel cleared it easily without hesitation. On this occasion both vehicle where fitted with 35" BFG muddies.

We kept heading north via the Mt Sunday Road and then south along Son Of A Bitch Track to Mountain Ash Track were we camped on the Barkly River.

Danielle seemed to be happy with the days drive.

The next day we headed south along the river and back into Licola, morning tea at the general store seemed like a good idea. At this point we decided to head across to Walhalla via Burgoyne Track and Deep Creek for a Late lunch at Walhalla and then home via the car lovers at Moe.

The next trip was over to Perth to take part in the Perth 4WD Caravan and Camping Show. This trip consisted mostly of driving on the black top with exception of approximately 400km of dirt road between Norseman and Wave Rock. Danielle and Aaron flew over from Melbourne to help us out with the show. After the show Denny and I flew home while Danielle and Aaron drove the Nissan back home. Several side excursions took place while on their way home, between the four of us we managed to clock up well over 10,000km.

Early in February 2007 we headed for Robe in South Australia. Robe is a seaside town about 450km west of Melbourne and about the same distance south west of Adelaide. Robe is a popular place, renowned for great fishing, camping and above all. driving on the sand dunes and beaches.

On this trip we clocked up another 1,500km plus.

On the weekend of the 24th and 25th of March we attended the Tuff Truck Challenge located on a property near Singleton, North West of Sydney.

The following weekend we attended OzRock 4X4 at Walbundrie NSW.

The following weekend we where back to NSW to visit some friends in Cowra. This trip bought the total distance travelled on the portals to over 38000km. In the next couple of weeks we will hit 40000km, and will be striping down the portals for another routine inspection. We have travelled 30000km since the last inspection.