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Airbag Suspension Systems - Part Two

We road test a Holden ute riding on fully adjustable airbag suspension!

Words by Michael Knowling, Pix by Julian Edgar

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At a glance...

  • Final of two-part series
  • Road testing a stand-alone airbag suspension system
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Airbag suspension systems can absolutely transform your vehicle for towing heavy loads or, alternatively, they can be used to create that eye-catching ‘low rider’ stance. In the first part of this series (see Airbag Suspension Systems - Part One) we looked at the different types of airbag systems, their advantages and pricing. Well, now it’s time to put airbag suspension to the test.

Let’s take a close-up look at Airbag Man’s Holden VYII Commodore SS ute and hit the road!

Airbag Man Development Ute

This VYII SS ute is Airbag Man’s R&D mule and, when we sampled it, it was using a Firestone airbag at each corner and in-cabin control with two preset ride heights. We spoke with Airbag Man’s General Manager, Brett Curtis, on the details of the system...

Under the nose, the ute uses an aftermarket replacement strut assembly which has its coil spring and spring platform removed. The new platform for the triple bellow airbag unit is a custom cast alloy item which is attached to the strut using grub screws. Mr Curtis points out there’s no need to weld to the strut body (which can be a dangerous exercise).

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At the top of the revised strut you’ll find another custom cast alloy mount which accepts the top plate of the airbag. Note there are no dedicated bump-stops because, when fully compressed, the airbag acts like a bump-stop.

“Maximum suspension travel is usually determined by the stroke of the damper and movement of suspension links rather than the airbags,” Mr Curtis says.

Click for larger image

At the rear, the Holden ute comes fitted with a separate spring and damper setup which makes airbag installation relatively straightforward. A double bellow airbag unit is mounted over the standard spring platforms and is attached only at the top using heavy-duty stainless clips. The airbag remains captive in the same way as the standard rear spring.

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Air pressure for the airbags is generated by a 12V piston compressor which is mounted under the rear. This particular compressor draws up to 17.5 amps and can generate up to 150 psi. Air pressure is stored in an 8.5-litre reinforced vessel which is mounted under the rear alongside the fuel tank. Mr Curtis says a large volume pressure vessel helps improve the inflation response time of the airbags.

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Air pressure is supplied to the airbags via 150 psi rated hose (as used in air-brake systems) together with brass fittings and solenoids. There are six solenoids in the system. One pair of solenoids controls air entry/escape of the rear airbags and the two remaining pairs control air entry/escape of the individual front wheels. In this configuration, the front wheels are individually adjustable but the rear airbags operate in unison.

The solenoids are controlled by in-cabin switches wired to a ride height control module with two presets. The ride height presets are programmed via laptop.

On the Road

The Airbag Man R&D ute is the focus of on-going efforts but is indicative of what can be achieved with a stand-alone airbag system.

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With the car set to just over the standard ride height, the ride is very compliant and feels well damped. However, it feely wallowy through corners and the handling isn’t aided by the alignment specs well outside of the front-end’s ‘sweet spot’.

“To get the most out of the system you really need to have the wheel alignment set to suit your most common ride height,” Mr Curtis says.

The car can be raised further but this isn’t advised for normal driving – it’s only for negotiating steep driveways and clearing obstacles.

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With the car dumped to its lowest setting - about 40mm lower than standard - the ride is much harsher over bumps. Mr Curtis says, at this ride height, it’s possible the airbags are reaching the limit of their compression and are functioning as bump-stops. This isn’t a specific problem except for the deterioration in ride quality. Take a close look at this photo and, again, you’ll see wheel alignment angles are clearly different to the elevated ride height. Some experimentation with alignment specs would certainly be beneficial.

The only other downsides are slightly increased NVH transmitted through the new strut top-mounts and an occasional popping noise from the airbags when lowering the vehicle. Brett also points out that this system uses relatively small 1/8 inch solenoids which don’t give the rapid ride height change achieved with larger diameter solenoids.

Interestingly, the system is also configured so - in the case of an automatic transmission vehicle - you can’t lower the car when in Park. This causes driveline windup which can damage the transmission. The solution is to adjust ride height only in Neutral and with the handbrake lightly applied.

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Since our photo shoot, Mr Curtis says they’ve revised the front upper airbag mounts for a neater appearance and are currently installing a more sophisticated control system. As we said, it’s an R&D vehicle...

Price and Availability

Airbag Man’s complete On-Air airbag system for the Holden costs around AUD$4500 plus installation (which takes about a day). That’s not too bad when compared to some adjustable coil-over suspension which, of course, can’t be adjusted from the cabin.

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At present, Airbag Man offers stand-alone suspension systems to suit Holden Commodore, Subaru Impreza WRX, Honda Civic and Integra. A system for Ford Falcons is also being developed. Each system comes backed with a 12 month warranty.

With some fine tuning in the area of wheel alignment, we reckon an airbag system would be a great addition to any car that’s receiving ‘the works’. No longer do you need to put up with a permanently slammed ride height and a jarring ride to impress your mates.

At last – there’s a real alternative to a coiled up piece of steel!


Airbag Man +61 7 3889 6556

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