4WD MODIFICATIONS - GENERAL MODS
Our Outback Travel Australia restoration project, rebuilding and modifying a LandCruiser 75 Series tray-back, is an ongoing exercise.
Our OTA project vehicle could hardly be more different from our first. We’d tested the revolutionary Land Rover Discovery 3 and reckoned it was the best wagon on the Australian market, so we bought one and drove it outback for three years and just under 200,000km.
It never let us down in the bush, went through trackless deserts without major issues and was the most advanced 4WD wagon in our estimation – soured by lousy quality control and computer-related issues that Land Rover Australia wasn’t interested in curing. If the Japanese or Koreans had built it we’d probably still have it!
Our current project is as far – electronically speaking – as you can get from a Discovery: it’s a LandCruiser 75 Series tray-back that already had 300,000+km on it. It doesn’t have a single piece of electronic gadgetry in it – apart from the radios, an infotainment screen and a Doran tyre pressure monitoring system.
We’d christened the Land Rover ‘Larry’, so the 75 Series HJ just had to be ‘Harry’.
The first step in this project was a wheelbase stretch, organised by a restoration mate of ours on the Gold Coast. Geoff Ansell ran Nuban Bodyworx and he was much better at painting than he was at spelling!
Harry’s stretch added around 750mm to tray length, allowing us space to fit a large toolbox/fridge box on the back and still have plenty of room for a slide-on camper. The extension was engineer-approved to tight NSW rego standards.
A mechanical check revealed the engine was in top nick and the fuel system should be good for another 50,000km. The extractors were repainted, the radiator was recored, a new power steering pump and reservoir fitted, and a new fuel filter pump installed. New swivel hubs, brake rotors, pads and wheel bearings were fitted. The wheelbase stretch required a jackshaft and centre bearing – the latter being an Isuzu light truck component.
A rolling kit upgrade included six ROH steel Blak Trak mine-rated wheels, with the two spare wheels mounted behind the cab.
We opted for a complete tear-down of the cab panels, clean up, filling, sanding and respray. The cab was bolted back together with new rubbers and plenty of Sikaflex. At the same time, Nuban organised a set of drop-sides and a tailgate, and these were finished in the same colour as the cab.
We did up the interior ourselves at OTA headquarters, in the NSW Southern Highlands.
This involved stripping out the cab interior and cleaning, painting and polishing everything that stood still.
Because the 75 Series isn’t renowned for its cabin ambience we resolved to quieten the beast, seeking advice from Tru-Fit Automotive Products.
Sound Shield under-bonnet foam went on easily, thanks to its aggressive adhesive upper surface. We applied sticky-back Resomat Premium sound deadener to the interior panels, finding it very easy to work with.
On top of that went Premium Underlay foam laminate and finally, replica vinyl floor coverings. We have a roll of aluminium/foam noise and heat barrier on standby, in case we need it.
Next came a furniture upgrade. The 75 Series seats weren’t real flash when new and these ones had certainly passed their use-by date. out they went and in went a pair of Recaro Specialist buckets, complete with adjustable centre arm rests and air-bladder adjustable lumbar supports.
A 2016 addition was a set of canvas seat covers that we’re still using.
We matched the new seats with new seatbelts. A Tailored dashmat dressed up the dashboard nicely and we’ve also fitted a Department of the Interior windscreen-top shelf.
Our next step involved brightening the road ahead.
The original glass-lens headlights were always on the dim side and vulnerable to flying stones.
Out they went, to be replaced by a pair of Narva 178mm (seven-inch) free-form-reflector halogens, with hard-to-crack polycarbonate lenses.
We checked them out with standard replacement H4 globes – very good – then a pair of Plus 50s – brilliant – and then a pair of Plus 120 globes – more brilliant, with obviously whiter light.
In 2015 the halogen headlights were replaced by a pair of Narva-distributed Truck Lite LED, dipping headlights. In 2017 we replaced these test lights with a pair of Hella LED test headlights.
We chucked away the standard radio and fitted a double-DIN nav/radio/Bluetooth/reversing camera unit we picked up from Hino Trucks. This unit was available with plug ‘n’ play wiring to suit the old LandCruiser.
Suspension Mark One
In August 2013 it was suspension time for Harry. We headed up to Newcastle, north of Sydney, and left him with the Powerdown boys for a day.
Out came the old suspension, with its tired springs and even more weary dampers and in went a set of new Kings Springs leaves, with greasable shackles and a set of RAW’s monotube dampers.
The Predator model fitted to our LandCruiser had a 46mm piston, 18mm hard-chromed shaft and a floating piston to separate the nitrogen gas charge from the damper oil.
Early impressions were favourable: more controlled ride, less cornering sway and better bump control.
We gave the springs and shocks a bush workout and found that the damper valving was a tad too firm for bush work on rutted roads. Two of the Predators leaked and we took them off. (See below for Suspension Mark Two.)
While we were evaluating the Predators we had some traction aids fitted. For the back end we chose our long-time ute-diff favourite, an Eaton Detroit NoSpin SoftLocker.
The beauty of this diff centre is that it’s locked most of the time, ‘camming out’ when cornering on high friction surfaces. Should a rear wheel start to lose traction the Locker immediately locks up, controlling spinout.
For the front end, where the main requirement is traction control to reduce wheel spin and the chance of busting a CV joint, we opted for a Detroit TrueTrac limited-slip differential.
This geared-typed LSD doesn’t have troublesome wet clutch plates, relying on geared action to reduce spin. At the same time, Craft Differential reset the diffs and fitted new bearings.
We ran the NoSpin in the rear diff for three trouble-free years until one day the pinion nut fell off, grinding us, literally to a halt.
Part of the diff rebuild was a new Harrop ELocker that has been getting a serious workout since 2016.
Harry came to us with a Toyota ‘roo bar, but it was too narrow for fitting side rails, so he went to Opposite Lock in Sydney, for some more robust bar work.
The body mounts that were fitted during the wheelbase extension looked a tad on the light side for our planned excursions, so we dropped Harry off at Betts Welding in the NSW Southern Highlands for some heavy duty attention.
The boys duplicated the Toyota factory mounts, put in a heavier cross member and shortened the tray rear overhang by 250mm. At the same time they modified the drop sides, to fit behind a storage box that neatly matches our slide-on Tray Tek camper.
The idea is that we can use Harry as a general purpose ute when we’re at home and then remove the drop sides and slide on a camper when we want to go bush.
Having the storage box and fridge slide allows us to have some secure stowing space and a fridge, even when we don’t have the camper on board.
Harry sported a towbar, but it looked like it had done a lot of hard work, so we swapped it for a new Carasel (not our spelling) unit.
After checking out the available slide-on campers in the market we chose a Traytek Tailgater Plus model. Traytek campers are now part of the Trayon lineup, giving this company hard pop-top and side-opening slide-on campers.
We picked up the Traytek in April 2014, but we made sure it would fit nicely, during a previous trip to Brisbane.
With the loaded camper on the tray, Harry’s rear suspension went down by around 45mm and we could feel the rear springs flexing as far as the helper leaves, giving a sudden increase in spring rate and and an uncomfortable ride.
Suspension Mark Two
We visited Sydney Shock Absorbers (Heasmans) in Sydney for some assistance. (Allan Whiting’s association with this company goes back as far as 1966 when Heasmans set up the suspension on his GT 500 Cortina rally car.)
R&D Manager Paul Joyner prescribed a pair of Polyair Bellows Series air springs to restore rear suspension ride height and a set of Bilstein monotube dampers to control spring action. What a transformation!
With only 30psi in both air bellows, unladen ride height was restored and ride quality was the best it’ had ever been.
The Polyair Bellows springs can tolerate pressures up to 100psi, for maximum assistance and are easily adjusted via remote tyre-type valves. They’re designed for heavier-duty applications than the familiar red Polyair units.
We know there are other air bellows products in the marketplace, but we’ve had bracket issues with some of them on bush trips and we were much happier to go with the Polyairs.
After 20 demanding outback treks the suspension was as tight and as fade-resistant as it was when new.
2019 suspension upgrade
After much research into suspension options we bought a set of parabolic front springs from well-respected Westralia Springs.
They fitted perfectly and our engineering mates at Bilstein checked that the valving of the front shockers was well-matched to the new, lighter and more flexible springs. To read about the design and characteristics of parabolic springs, check out our Tech Torque story.
Our initial impressions were good: ride quality was markedly improved and steering and handling were also more responsive. We gave the new springs a good workout during our winter travels in 2019 and had no issues at all.
However, after around 40,000km we noticed some sagging in the parabolics, so off they came and were replaced by conventional multi-leaf springs from Tough Dog.
We’ve also been testing Tough Dog adjustable dampers since 2020 and like them very much. Check out the test results.
We know that the 75 Series comes with a standard snorkel, but ours was showing its age and had developed a crack near the top mounting. Another factor was the somewhat restrictive design of the standard snorkel, which is narrow in section and has a relatively small hole into the air cleaner. The entry is also restricted by a diffuser plate inside the air cleaner housing.
We picked up a replacement snorkel from an Opposite Lock outlet. Safari’s design employs a larger volume snorkel pipe and larger air cleaner entry nozzle. The diffuser plate is drilled out and discarded during fitment.
In conjunction with a scoop cap the freerer-flowing snorkel is claimed to improve performance, by reducing engine pumping losses. After around 10,000km with the new snorkel we could vouch for increased mid-range response, yet there was no increase in fuel consumption, suggesting that the engine was breathing more easily.
The snorkel kit for the 75 Series was boxed and came with cardboard templates for cutting and drilling, plus all necessary fasteners and fittings.
A comprehensive instruction booklet, with accurate pictures, made progress logical and simple.
The instruction sheet reckoned the whole process was a three-hour task, but it took me five. I think I could do it again in about four. Two people could share the job, with one fitting the snorkel to the vehicle body and one modifying the air cleaner, to bring the time back to around two hours.
I was impressed with the quality of the Safari kit that needed no additional fasteners and with the way the parts fitted. The instruction booklet was spot-on. (For step by step snorkel fitting check out the story in our DIY section.)
After some hard trips Harry’s injection pump began to falter, so in it went to AJ Automotive in Bowral for a rebuild, plus new injectors and glow plugs. He then pulled better than a new 75, thanks to the enhanced breathing provided by extractors and large-volume snorkel plumbing.
AJs also fitted a Water Watch with loud water alarm and, having picked up some moisture at a bush refill, we can vouch for its performance. It was easy to drain the water from the bowl and refit the electrical plug to the sensor.
Increased engine performance highlighted the marginal state of Harry’s brakes – never a 75 Series strong point.
Bendix suggested improvements, in the form of specialised Hybrid SUV pads and high-friction handbrake shoes, in concert with a set of new TRW discs.
The job was done at Heasmans and there was an immediate improvement in handbrake holding power, particularly when facing downhill.
The brake pedal felt more progressive and ultimate stopping power was greatly improved.
A year on, the brakes lost some bite, so we started playing around with some changes. First to go were the old brake lines: replaced by Safebrake PTFE,
stainless-steel braided replacements. At around $350 for the complete vehicle they weren’t cheap, but they came with a five-year warranty
Brake testing on-road showed an instant improvement in braking power, so the old rubber lines must have been tired.
On a bush trip Harry’s rear 90-litre tank sprang a slow leak. Rather than replace it with a newer stock item when we got home, we opted for a 160-litre replacement tank from LongRanger. That gave us a total of 250 litres tank capacity for long, remote-area bush trips.
Although Harry is a 1993 model, supplying the replacement tank was no problem for LongRanger, who produce tanks for virtually every 4WD in the market.
The replacement re-used the original fuel pick-up and gauge float and sender, and fitted snugly into place.
The kit came with all the hoses, fasteners and clamps necessary to complete the job.
The refit took around four hours and the service was typical of what we’ve become used to at LongRanger (Newcastle NSW). We’ve had LongRangers in all our OTA bush expedition vehicles.
Serious powertrain upgrades in 2018
By 2017 we’d decided that we didn’t want
to replace Harry with any of the modern utes in the marketplace. None of them would do what we wanted and all of them had electronics and emission control systems that we didn’t want to take seriously bush.
We bit the bullet and paid for a complete rebuild of Harry’s gearbox and transfer case, plus new propshaft, half shafts and swivel hubs.
Then it was time to assess the engine situation. With our fully loaded camper and topped up fuel and water tanks Harry used up all of his engineer-approved GVM upgrade to 3.3 tonnes.
With the boat trailer behind as well his performance on highway grades was, er…modest. We were running the risk of being shunted up the bum by loaded B-Doubles!
We took Harry to the experts at Berrima Diesel, for power and torque improvements. Andrew Leimroth checked out the 1HZ and pronounced it fit for mild turbo’ing. We’ve always been wary of fitting turbochargers to engines that weren’t designed for them, but Berrima Diesel has been doing this job for many years, with great success, provided people don’t ‘fiddle’ with their dyno-proved fuel and boost settings afterwards.
Also, we were reassured by the fact that Toyota did produce a factory turbo version of the 1HZ – the 1HZ-T – that was fitted to Coaster buses in Europe, before the advent of the direct-injection 1HD-T. However, that factory engine had different pistons and rods from the non-turbo version. More on that topic follows below.
The job started with a third-gear dyno test that revealed Harry’s very modest rear wheel horsepower figure of 59.8kW.
Off came the standard inlet plumbing and
the extractors, and in went the DTS turbo kit’s inlet plumbing and exhaust manifold. Because the extractors had replaced the standard exhaust system a length of exhaust pipe with flange had to be made up to mate to the turbo-kit’s exhaust manifold. Then on went the Mitsubishi turbo.
Oil lines and water pipes were connected and an exhaust gas temperature probe was fitted to the exhaust pipe. The gauge fitted neatly beside the LandCruiser instrument binnacle, giving a clear readout of boost pressure and exhaust temperature.
Back on the dyno there was an immediate improvement in output, even with the standard fuel pump settings. Rear wheel horsepower went up to 63.1kW. After pump adjustments the final figure was 75.6kW – a 25 percent increase.
Third gear calculated torque was originally 374.5Nm; went up to 425.6Nm before fuel pump adjustment and finished at 502.2Nm – an increase of around 130Nm, or 30 percent.
In its original form the 1HZ engine operated
under load with an almost exact stoichiometric air/fuel ratio of 14.7:1 (the weight of air required to burn the corresponding weight of fuel injected).
A stoichiometric ratio is critical for safe and efficient combustion in petrol engines, but diesels are happy to operate at lean mixtures and suffer no penalty from excess air, unlike petrol engines that run hot when leaned off.
The advantage of a lean diesel mixture is less smoke, thanks to better combustion at full load and when accelerating. With his new turbo spinning Harry ran an air/fuel ratio mostly in the 18:1 to 21:1 range.
On road, the difference was stark. Harry was a gear better on our test hills and made no smoke at all, even under harsh acceleration. Flexibility in all gears was improved and engine noise levels were much lower, thanks to the ‘rotary silencer’ that chopped up the inlet tract noise.
We tested Harry under load by pulling a car trailer with a mate’s ancient Land Rover on its back. Very satisfying, that! Towed weight was exactly 2.5 tonnes. On the flat Harry was unfazed by the trailing weight, so we pointed him up the 10-percent grade from NSW’s Kangaroo Valley to Moss Vale: a 25-kilometre slog on tight, winding bitumen.
Our eyes were glued to the Redarc pyro
throughout this climb, which we managed mostly in second cog, with a feathered accelerator pedal and revs around 2000rpm.
The gauge registered maximum boost of only six psi; the exhaust temperature ran in the 250-350C range and the coolant gauge needle didn’t move for the entire climb. Not much combustion stress there, we reckoned, even allowing for the fact that the pyro probe’s positioning after the exhaust manifold is likely to register around 100C lower than the actual exhaust valve temperatures.
We tried third gear at times, but the pedal went to the floor,
revs fell back, road speed didn’t increase and boost and exhaust gas temperature started to rise, so we reverted to second.
Before the turbo fitment we know Harry would have held second on the straighter bits, but with a flat foot and he’d certainly have need to drop into first for the tight corners.
On-highway driving, with Harry only lightly loaded, was done mainly in fifth gear and hills that previously saw us back to fourth at 80km/h were conquered in fifth at 105km/h. Boost never exceeded 10psi and exhaust temperature was typically 300-350C, with one climb to 400C for a few seconds. The coolant gauge needle didn’t move off its normal position.
Our next trip was done with the Tray Tek camper slid onto the back of Harry and the Hobie trimaran and boat trailer bobbing along behind. Flexibility was greatly improved and we found a two-day highway driving stint quite relaxed. We managed all the freeway and highway hills in fourth and fifth, where before we needed third on quite a few climbs.
Overall fuel economy was a slight improvement over previous 12-15L/00km figures.
Longer term testing proved successful, but we keep a careful eye on vital fluids, because the weak links in turbocharged 1HZs are the pistons and rods that weren’t designed for turbo combustion pressures. Factory 1HZ-T engines were fitted with different pistons and rods.
We were disappointed, but not entirely surprised, to find oil and coolant leakage from the back of Harry’s cylinder head at the 520,000km odometer mark, in July 2022. There were also small flecks of oil in the coolant. Rebuild time.
For a full report on the rebuild, check out our story in the Powertrain section of the website.
Once the rebuilt engine is run-in we’ll do some performance and fuel consumption comparisons. Early impressions of the new engine are better mid-range acceleration, cooler, smoother running and reduced fuel consumption. Watch this space during 2023.