FINE TUNING

Buying a new or used ute is just the start of a process to ensure your purchase is fit for purpose

When asked by readers as to which vehicle we recommend for them, our answer is always the same, it all depends what you intend to do with it.

The aim of all the ute manufacturers is to provide a vehicle that is safe, complies with Australian Design Rules and is perfectly capable of conveying a combination of load and people. The problem comes after purchase when the buyer wants to mix and match the people and load carrying ability with towing a heavy trailer.

The manufacturers are almost universally claiming a towing capability of 3500 kg for their latest products, the exception being Mitsubishi, which, together with Mahindra, Tata and Great Wall, stipulate a lower maximum tow weight.

The Gross Vehicle Weight is the total weight of the vehicle plus the load it is approved to carry. The Gross Combined Weight is the total weight of the vehicle, plus the load it can carry, plus the load it can tow. When you add accessories to your vehicle such as a bullbar, driving lamps, winch, rear canopy, tow bar and perhaps long-range fuel tanks, you reduce the payload or towing ability by the amount of weight of this extra equipment. From that point on, your vehicle is going to underperform, and, in a serious case of overloading, it will neither be fit for purpose nor safe.

When towing a 3500 kg trailer with a towball downforce of 300 kg, the driver must reduce the amount of payloaUltimate-Suspension_P2d in the towing vehicle by 450 kg. So, your one-tonne potential payload in the cargo area is now just downgraded to 550 kg. If you add four tradies to the interior, each weighing 110 kg, your payload is then reduced to just 110 kg. And, if in the meantime you’ve added a bullbar and winch plus other accessories, you will actually have a vehicle that is overloaded before you put anything in the cargo area.

So, the option of heading off with all the family for a two-week camping holiday towing a heavy trailer is no longer feasible. Despite the best of intentions, the application required of the vehicle now means it is not fit for purpose.

Fortunately, there is a solution, and it comes in the form of visiting an Australian suspension specialist that is well versed in finding the right upgrade for springs and shock absorbers.

As a practical example, Delivery visited the headquarters of Ken O’Keefe’s Ultimate Suspension in Ingleburn, on the outskirts of Sydney, with our trusty Isuzu D-Max space cab. With 43,000 km on the odometer, the suspension was showing signs of sagging at the rear, with the helper springs on the semi-elliptical leaf pack being positioned against the upper leaves without the necessary clearance. The front coil springs were also looking a little depressed and the shock absorbers were not providing the correct amount of damping, especially on corrugated dirt roads where it set up a bouncing motion.

Ultimate’s technicians started off with a thorough examination of the complete vehicle, including measuring the weight downforce of each wheel, the braking ability and the attitude of the vehicle by way of height clearance at each wheel centre. During this examination it was also noticed that the bump stops were leaving their mark on the chassis, suggesting that it’s ability to carry heavy loads was certainly not up to par.

Armed with the weight readouts for each wheel, the team selected a King Coil tapered wire coil spring as a replacement for the front suspension, mounted with an Ultimate Suspension shock absorber.

Each Ultimate unit is specially adapted to achieve the correct valving and thereby provide the right control for the intended weight-carrying potential, plus achieving the correct handling response for the vehicle in the application in which it is used.

Now to the rear. With the leaf spring packs showing a definite sag they were replaced with new Ultimate leaf springs rated for the types of load to be carried and the road conditions on which this ute usually travels.

New spring hanger assemblies for the rear spring mounts were fitted and these differed from the original units as they incorporated grease nipples, meaning that servicing is now possible on a regular basis. The rubber bushes in the original spring hangers were showing signs of ovalising and were replaced by new neoprene bushes. At the same time, new “U” bolts were also fitted to secure the axle assembly over the leaf spring pack, and, once again, the replacement Ultimate Shock Absorbers were specially valved to match the intended payload.

Ultimate-Suspension_1With everything bolted back up, a final torque wrench check on the “U” bolts and other main components completed, the D-Max was then given a full wheel alignment at Tyrepower Ingleburn, adjacent to the Ultimate workshop. This was followed by an on-road test prior to running the D-Max back over the brake balance test unit. The weight downforce at each wheel was again checked, as was the ride height over each wheel centre.

For most suspension shops the work would probably stop there, but with the usual Ultimate attention to detail, the headlamps, Hella LED driving lamps and also the Hella LED light bars attached to the bullbar were checked on a beamsetter and repositioned to suit the different ride height and fore/aft aspect of the ute.

Before getting the Ultimate Suspension treatment the D-Max showed measurements from ground level to the top of the wheel arch through the centre of the axle of 865 mm for the front nearside and 875 mm for the front offside. The floor to underside of tray measurement through the centres of the rear wheels showed 910 mm on each side. After fitting the new springs the dimensions showed a consistent 900 mm for the front and 955 mm for the rear.

The return trip for the D-Max back to home base was a revelation in terms of how much improved the new suspension system was when compared to the previous original equipment. The harshness caused by the tired helper springs impacting even when unladen on the main spring leaf pack was removed completely, and the ride and handling was now better controlled and much more compliant.

What this exercise proved is that the original equipment suspension system supplied by the vehicle manufacturer at the time of purchase is at best a compromise.

In the same way that a mechanic tunes the engine to gain its best performance, so too does the suspension have to be tuned to be fit for purpose. This is especially relevant for those using a ute for business purposes where it carries a regular load and then may also tow a trailer.

You basically get what you pay for. It might seem to be an unfortunate additional expense to replace suspension, especially on a brand-new vehicle. However, when you add the additional weight of accessories and equipment to a standard spec’ vehicle, and want the final result to perform to your expectations, and provide safe and durable results, it’s the only sensible and safe solution.

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