VF COMMODORE: Steering a new path

While there are many changes from VE to VF Commodore, nothing has created more attention than Holden’s decision to swap from hydraulic to electric power steering assistance for the rack-and-pinion steering system.

Electrical Power Assisted Steering (EPAS) is often criticised for its reduced feel and decisiveness, yet here’s Holden trading in one of the VE Commodore’s greatest strengths for it! But the fact an electric motor is inert at the straight ahead, placing no load on the engine or the fuel tank simply makes it too important to ignore for VF in an age when economy is paramount.

“We embraced it,” said Holden chassis tuning guru Mike Barber.

“Fuel economy is so important, it [EPAS] is low-hanging fruit and you have to go after it. You can see the penetration of EPAS through cars now – if it hasn’t got it, it’s about to get it. It’s across the board, so you can’t stop progress. So absolutely embrace it, learn it, understand it and make the most you possibly can from it.”

While Barber contributed to the program, which was underway with Korean steering gear supplier Mando by early 2010, it was his equally talented colleague Rob Trubiani who led it.

The Nurburgring accredited test driver came up with three different tunes: Touring for the Evoke, Calais V and Caprice V; Sport for S and SS models; and Track for the SS-V hero model (which can be toggled between Sport and Track settings). Each one simply gets sharper, weightier and more responsive.

At the same time Holden moved back from a variable to a linear ratio rack because EPAS alone can provide the lightness it needed at parking speeds and the weight it wanted on the highway.

In terms of hardware, the biggest chassis change was the swap from cast iron to alloy front knuckles and a tension rod with new bushes and ball joints. Other changes include new upper control arm bushes in the rear suspension, redesigned shock mounts, recalibrated and quieter shock absorbers and new 18 and 19-inch ‘comfort’ tyres designed with Bridgestone.

Holden also swapped to an electric park brake (and because of its emphasis on refinement for the VF, it worked hard to eliminate the signature ‘whirr’ when it engages); improved brake response via a new pedal, master-cylinder and booster and an upgrade from Bosch ESP 8.0 to 9.0 (including trailer sway control and hill start assist on manuals).

“Small changes add up,” explains Barber. “If you can add several of them together you would be amazed how you can transform the car.”

There are three levels of suspension tune under the VF models (FE1, FE2, FE3), which are split up among the models the same way as the steering tune. FE1 has been worked over heavily to make it sportier and more controlled while retaining ride comfort. FE2 is broadly similar to its VE predecessor, but FE3 goes through a significant upgrade.

The obvious change is tyre size, with Holden taking a leaf from HSV’s playbook. The Redline now runs a new 245/40ZR19 on the front and wider 275/35ZR19 on the rear, developed with Bridgestone.

The FE3 tune also gets an internal rebound spring for better grip (but it also provides better comfort for the Calais V and Caprice V), fatter stabiliser bars, stiffer rear springs than FE2, a ‘competition’ mode for the stability control system and a launch control function for the manual.

“Moving to this big rear tyre is such a game-changer in terms of the grip it develops and how you can manage that grip,” says Barber.

“It doesn’t bear much resemblance to the old FE3,” he said.

Links to motoring.com.au’s VF Commodore news
>> Mission accomplished: Holden had simple aims for VF
>> Aero Dynamic: Pedestrian safety and aerodynamics have shaped VF
>> Inside Job: Fewer parts and better materials drive VF Commodore’s interior upgrade
>> Large car future proofed: VF’s new electrical platform plays a vital role
>> Power games: Carry over powertrains don’t detract from VF story
>> Getting connected: VF delivers impressive connectivity
>> Safely integrated: No US-spec kneebag but Holden says VF is safer

>> First Drive -- VF Commodore SS
>> First Drive -- VF Commodore Evoke
>> First Drive -- VF Commodore Calais V
>> First Drive -- VF Commodore SV6 Ute
>> Along for the ride: In a very small way motoring.com.au played its part in the VF

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