Here it is – a world first!
Australian handling and suspension gurus,
Whiteline, is the first company in the world to develop an aftermarket
controller for factory stability control systems. This groundbreaking product
puts another world of handling control literally at your fingertips. You want
to change the action of the stability control system? Just turn a knob...
Jim Gurieff, the head of Whiteline, says it’s no
longer enough to focus on traditional suspension modifications (such as springs
and swaybars) to deliver true high-performance handling. Sure, you can whack on
new suspension bits but, until now, there’s been no way to override the strategy
of factory stability control systems. The limits of oversteer and understeer
have already been defined by the control system.
But all that has now changed.
The Whiteline Handling Bias
Modifier
The prototype Whiteline Handling Bias Modifier (note - that
name is yet to be confirmed) is the product of two years development by the team at
Whiteline and a qualified electronics engineer. The prototype unit has been
developed exclusively for the Holden Astra Turbo. This might seem like an
over-investment in a car that sold relatively poorly in Australia, but Jim sees
it as an investment in the future – by ‘cracking’ the Astra Turbo system, he can
now turn his attention to other vehicles equipped with Bosch stability control
systems. He has also built a greater understanding of how to tackle non-Bosch
control systems.
Understandably, Whiteline don’t want to divulge
the nitty-gritty tech details but we can tell you their HBM operates on the
principle of intercepting and changing electrical signals related to the
stability control system. This might sound easy, but the Astra Turbo (like many
other cars with stability control) uses CAN bus communication which makes
intercepting much more difficult. A lot of effort went into refining the
unit so that it wouldn’t cause error codes in the factory system.
There are two primary control knobs on the prototype HBM
module – the left knob adjusts “bias” while the right knob adjusts “magnitude”.
The bias knob controls the vehicle’s balance toward understeer of oversteer. The
default position for the bias knob is 50 percent and by turning it up you’ll
trick the stability control into adopting an oversteer bias. In essence, the
magnitude knob controls the strength of the stability control system. The
default position for the magnitude knob is 100 percent and by turning it down
you’ll reduce the severity of stability control operation and cause the system to be
later in its intervention. So, put simply, one knob controls handling balance and the
other controls the power of the stability control system.
Whiteline purchased an Astra Turbo largely for the
purpose of developing a stability control adjuster but, in addition, there is a
range of suspension upgrade components available. At the time we drove the car
it was equipped with the Whiteline Works package. This comprises front
and rear swaybars (adjustable at the rear), front camber bolts and castor kit,
rear camber and toe adjustment kit, lowered springs and adjustable dampers. So,
without making any adjustments to the stability control system, the car already
handled better than a stocker.
On the Road
Driven with the two knobs at their default
positions (the bias knob set to 50 percent and the magnitude knob at 100 percent)
the stability control system performs like standard. In this factory calibration the
stability control intervens quite early – individual brakes are applied to
help limit understeer when pushed but it’s still far from neutral. In no
conditions can the car be provoked into oversteer.
From its default setting, the HBM can be adjusted
to give your desired handling characteristics.
Our preference was to turn down the magnitude dial
to give later and less severe stability control intervention. On the road, we
found this gave the best combination of speed, stability and control.
But what about the bias adjustment knob – the knob
designed to give oversteer/understeer control?
Well, interestingly, we found the bias knob is
best left near its default setting. By turning up the bias knob, the stability
control system will apply the brake to the inside front wheel through corners to
help induce oversteer. And surely that’s a good thing, isn’t it?
Well, this is where the water gets a bit
muddy.
From one perspective, the ability to dial-up
stability control induced oversteer in a car that’s a natural understeerer
equates to more neutrally balanced handling. But there’s more to it than that.
The type of oversteer induced by the stability control system is different to
the oversteer you’ll normally experience. The stability control induced
oversteer arrives in a series of wheel-specific brake applications which are at
the discretion of the control system and are not smooth or progressive. In fact,
when circling a largish roundabout at full-bore, the oversteer motion arrives in a
series of small lurches. In response to this, Jim points out that a lot of
testing was performed at Wakefield racetrack where small bias adjustments gave
no lurching problems through faster, flowing corners.
From our perspective, the concept of using the HBM
to alter the vehicle’s oversteer/understeer balance is not the best approach –
your desired handling balance will come tied to those small lurches that are
unavoidable when using on-off-on-off brake application. You can never achieve
smooth handling. In our opinion, a better approach is to combine the HBM with
some extreme suspension mods. For example, bolt on what would normally be considered an
overly stiff rear swaybar to help promote ‘natural’ oversteer and use the HBM to
set a safe oversteer limit. In other words, use the stability control system
primarily as a safety net when things get out of control - eg when that big rear bar causes a sudden throtle lif-off oversteer moment on a wet road.
Final Development, Installation and
Price
Jim from Whiteline says it will be late 2006 before
the HBM will be made available to the public.
Suitable enclosures are yet to be sourced and there are some important decisions
to be made regarding how much control will be placed in the hands of the
user. At this stage, Whiteline is considering releasing two different versions
of the controller. Whatever eventuates, Jim insists the unit will cost well
under AUD$1000 – and that’s a bargain!
Once released, it is expected that installation will be available at selected Whiteline dealers.
Contact:
Whiteline Suspension +61 2 9603 0111
www.whiteline.com.au
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