HDT Special Vehicles "Brock" Commodore VK

The HDT Commodores would be initially released as just two models, the HDT Commodore SS and HDT Commodore SS Group Three. Other models would follow, including the now highly prized and collectable “Group A”.

The HDT SS carried over the same grille from the donor VK Commodore, but had a small rear spoiler and 15x7 HDT wheels shod with Uniroyal ER60H15 tyres fitted.

But it was the Group Three that was creating all the interest, with its additional air dam, bolder side skirts, rear under-tray, letterbox grille and larger rear spoiler.

A rearward facing bonnet spoiler and bonnet wind splitters that ran atop the front guards were popular options. Colour options were restricted to either silver or white, the previous black never proving popular but we cannot determine just why red was abandoned.

Under the bonnet, the engineers enlarged the cylinder head ports, while the combustion chambers were gas flowed by Perfectune, before the engines were sent back to HDT for final assembly, including fitment of the bigger than standard valves.

Bilstein gas pressure shocks were fitted, along with a reinforced front say bar. Finally, the car was fitted with three-piece 16x7 alloys shod with Pirelli P7 225/50x16 tyres (although you could option Yokohama A008 or Goodyear NCT’s).

It was early in 1985 that Australian Touring Car racing moved from Group C to international Group A regulations, in the process changing the homologation rules to require some 500 examples of any car be manufactured before it could be raced. The General immediately turned to Peter Brock for the answer.

Starting out on the new “Group A” iteration, the HDT engineers needed to reduce the capacity of the trusty Holden 5.0 litre V8 to be less than 5 litres, so the first job was to reduce capacity from 5044cc to 4987cc – achieved by shortening the stroke from 77.8mm to 76.8mm.

In addition, the inlet manifolds were port matched and tubular exhaust headers were fitted. The engine was then mated to a M21 four speed transmission, the Group Three suspension fitted, the package then riding on 16 inch HDT alloys shod with Bridgestone Potenza 225/50 VR16 tyres. Cosmetically, the Group A carried over the Group Three’s grille, but was fitted with a “pimp my ride” large rear spoiler, and all were finished in “Formula Blue” duco.

Before the VK model was replaced, the HDT engineers had one more trick up their sleeve – the HDT Special Vehicles Calais Director. Most were built to customer order, and were twice the price of a standard Calais V8. Why would anyone want one over the Group A? You only needed to look at the corporate car-parks of the time, it would have been much easier to point to the Director and explain to your boss that your new company car was “merely” a Calais.

In all, some 700 HDT Special Vehicles Commodores would be manufactured, 200 Group Three's and 500 Group A's, while there were a handful of other HDT specials also.