SPRING HAS SPRUNG

Delivery finds the coil-sprung Navara NP300 has some shortcomings in the spring department

It was in July last year that Delivery magazine was first introduced to the all-new Navara NP300. A drive programme through its home manufacturing base of Thailand enabled an early evaluation in the spectacular scenery of Chiang Mai where everything seemed almost perfect.

These were early days as far as the development of the NP300 was concerned. During the launch programme briefing by engineers involved in the development we discussed the proposed top-of-the-line model, the crew-cab with coil-sprung rear axle, but, at the time, the only vehicles available for the drive were those fitted with a steel semi-elliptical leaf spring rear end.

Discussions took place with engineers over whether it might be advantageous to extend the rear coil-spring alternatiNissan-Navara_NP300_P1ve from the dual-cab ute only to include the dual-cab/chassis version. But it was made quite clear the additional cost of the more sophisticated coil upgrade precluded it from being available on other models in the range.

Perhaps at the time that response should have rung some distant and perhaps rather faint alarm bells. Every development programme requires bucketloads of Baht (this being Thailand) to fulfil all requirements. If only one model was going to benefit from featuring coil springs, it could be the case that the bulk of the development finance went on the higher volume, more conventional leaf-spring suspension products.

Whether that is the case or not, Delivery has to voice its concern that all is not quite as it should be down in the nether regions of the coil-sprung Navara.

Ten months later, and the annual Delivery Magazine Ute of the Year contest enabled us to evaluate the NP300 Navara with coil-spring suspension, plus the other new ute arrival, the Mitsubishi Triton.

The Mitsubishi made the deadline with a week to spare, but, for Nissan, a slow boat from Thailand meant that as soon as the ship made its first landfall, which happened to be Perth, two Nissan gentlemen drove straight off the boat and headed for the east coast, aiming to arrive faster than the boat could manage and in time for the full drive evaluation.

The Ute of the Year awards this year was certainly going to be hard fought, with the new Mitsubishi Triton and equally new Nissan Navara NP300 hoping to take the crown from the reigning champion, the VW Amarok. Equally keen was Isuzu with its D-Max, Holden with the Colorado, Mazda with the BT-50, Ford with the Ranger and Toyota with the HiLux, albeit awaiting an upgrade.

As we drove the Navara NP300 dual-cab we were impressed with the styling, which shows a smoother outline than its predecessor and the interior benefited from what has been a major upgrade, with better instrumentation, clever graphics and options such as a selectable day/night screen brightness setting for the Sat/Nav display, rather than automatically going to a darker image at twilight.

If you despair when syncing your mobile phone with different systems, you’ll find the pairing option in the Navara to be foolproof and very simple. And, when you return to the car after driving something else it re-syncs automatically. The same comment applies to the new Triton, which begs the question why some media units are so awkward?

The front seats in particular, with power assistance for the driver and heated seat squabs for driver and front passenger, are indeed a major upgrade, with much better support and significantly improved comfort levels.

Nissan-Navara_NP300_3Load carrying in the second row of seating is made easier, especially when trying to protect the leather seat covers from scratches, by lifting the seat squab and clipping it against the backrest. The floor area underneath is covered by carpet and also contains two small lockers for tools and equipment.

Cab interior noise levels are very low, showing the amount of work completed in NVH control by Nissan. As has become the case with passenger cars, with much less noise intrusion from engine, transmission, tyres and road noise, it’s now possible to hear other sounds that were previously drowned out. The move to lower profile tyres has also brought more road noise that becomes apparent as all other noise levels drop.

On our first drive around the test loop used for the Ute of the Year evaluation, each of our judges felt the Navara rear suspension with an unladen tub showed a little jitteriness as it traversed the lower quality bitumen B-roads.

Adding the standard 400 kg load usually settles down the activity of the rear end, but, in the case of the Navara, the coil springs located on the live beam rear axle showed a major compression. Despite the maximum payload being quoted as 930 kg, adding the 400 kg load to the tub dropped the rear ride height by 60 mm, leaving just 5 mm of clearance from the rubber bump stops.

Displaying a noticeable tail down, bonnet up profile, a tape measure showed the NP300 had a disparity between the front and rear ride height of 40 mm, with the distance from the ground to the peak of the wheel arch for the rear to be 840 mm with the front showing 880 mm.Nissan-Navara_NP300_9

Delivery’s test course is selected for its variation of road surfaces and conditions. Some of the corners feature bumps on the inner line of the curve, and this unsettled the rear end of the NP300, causing it to hit the bump stops. This in turn added an element of bump steer from the back axle that upset the directional stability. Before a reader questions the speeds involved during this analysis, the road speed was well within posted limits and was the same speed at which all other contenders were driven.

The true definition of payload is the difference between the maximum permitted gross vehicle weight and the kerbweight of the vehicle. When towing a laden trailer the weight of the downforce on the towball also has to be considered, with a further payload deduction from the ute tray being made to compensate for the added weight at the rear.

Nissan, like many other current models from different manufacturers, sets a maximum towing limit for a braked trailer of 3,500 kg. The company advises that, with a 200 kg downforce on the towball, the payload of the ute should be reduced by 280 kg. In the case of a towball downforce of 300 kg, the cargo carried in the ute should be reduced by 410 kg.

If you do the maths, when carrying five tradies weighing in at around 110 kg each, plus a 410 kg reduction when towing a trailer loaded to 3500 kg, the vehicle is already technically overweight to the tune of 30 kg, before putting the crews’ lunch in the tub. To save further weight, the customary Blue Heeler may also have to be replaced by a Toy Poodle.

The general expectation amongst the Australian ute buyer is that the payload equates to the amount capable of being carried in the tray or tub. So, if the payload states 1,000 kg, that’s what will get loaded.

With the exception of the NP300, adding the 400 kg test weight to each the utes under evaluation didn’t significantly affect their ride and handling performance. However, with its tail down and nose up attitude, the NP300 didn’t run with a level ride height and was not fit for purpose.

So serious were the concerns of the Delivery test team about the shortcomings of the coil-sprung rear suspension performance that we provided Nissan Australia with a detailed evaluation of our findings, prior to the publication of the Ute of the Year Awards and about three weeks before the planned first test drive days involving local motoring journalists.

As one might expect, bad news travels fast, and in rapid time Nissan engineers were re-evaluating the suspension performance of the early vehicles off the boat to ascertain whether the suspension rating of the first imports were in line with the expected Australian specification.Nissan-Navara_NP300_8Within two days we received information from Nissan that they had replicated our experience and that further advice was being sought from Japan for an early solution.

Four days later, after a phone hook-up with Japanese and Australian engineers working for Nissan, a plan of action was agreed that the company would fly one of its executives from Japan to meet up with Nissan’s Australian engineers. Together they joined the Delivery team to replicate our findings on our own test circuit, running preliminary testing for two days over the Delivery course prior to a final joint evaluation.

During this drive programme, the Navara NP300 used for the testing was coupled up to a Data Logger with input from sensors placed on the vehicle to evaluate the performance of the suspension.

GoPro cameras were installed to record vision of the suspension components in action and specific points on the test course were highlighted for their affect on the vehicle handling. External video vision was also recorded of the Navara negotiating specific bends on the course, with comparisons of other competitive vehicles to show the different handling characteristics.

The close cooperation between the Nissan’s Japanese and Australian operations and Delivery Magazine highlights how seriously the company reacted to the flagging of the problem by our testing programme for Ute of the Year 2015. It also highlights how, despite super computers and digital analysis, there are still times when boots on the ground can prove to be more intelligent.

We could have just run the story with our findings as part of our Ute of the Year test and watched a manufacturer suffer the consequences. That may be the way some of the media, particularly the new crop of inexperienced web writers, may be focused, but it doesn’t match the integrity or credibility for which Delivery has gained its reputation.

Our findings show that, with the expertise in the field of light commercial vehicle evaluation of judges Stuart Martin, Chris Gable, Kurt Grossrieder and Chris Mullett, a major multinational vehicle manufacturer not only listened to our concerns, but reacted swiftly to investigate possible solutions.

Since our initial findings, Delivery has also been in contact with experts in the suspension aftermarket industry to discuss possible solutions. After investigating the spring and damper performance of the coil-sprung Navara NP300, leading Australian spring manufacturer, King Springs of Queensland, has worked quickly to develop a progressive-rate front and rear replacement coil spring that takes the suspension performance to Australian expectations.

The suggested improvemenNissan-Navara_NP300_10ts by King Springs are to replace the standard front spring rated at 450 lb with a 600 lb progressive rate coil spring to reduce body roll. The rear original equipment progressive rate spring was rated at 140-210 lb, and King Springs recommends replacing this with a 180-260 lb progressive rate spring. This will raise the rear ride height by approximately 35 mm, improving the load-carrying ability and restoring a higher degree of vehicle balance. A heavier-duty rear progressive spring option of 200-320 lb is also currently under development by the company.

This high level of industry cooperation should result in a safer, more competent vehicle that will perform to a higher standard in the Australian market. There’s no denying the Navara NP300 is an excellent vehicle, but with some local Australian knowledge it can be better.

Delivery is looking forward to evaluating the other new Navara NP300 models as they are released progressively in the months ahead. These differ in specification from the coil-sprung, dual-cab ute version by being universally fitted with leaf spring rear suspension. In the meantime, it will be interesting to see what variations are made to coil spring rates and damper settings to cater for the higher weights associated with the Australian market.

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