Successful and Influential Motorkhana Specials

 

  The Terrier Honda special was built by Wayne Griffiths between 1993 and 1999. It features a light spaceframe with carbon fibre panels. It has fabricated independent front suspension by wishbones, shocks and torsion bar springs. Rear suspension is a four link beam axle with coil-over-shocks. The all alloy engine was from an early Honda Civic, bored and stroked to 1510 cc with modified head, two twin choke Dellorto carburettors, custom exhaust and numerous detail modifications. The transmission is a Hondamatic - a 2 forward and one reverse automated manual with torque converter, much modified with altered diff ratio and a mild LSD.

Front and rear Honda disc brakes are used, while the wheels are 13" Circle Track composites. Rear braking is by a pedal on the left side of the car, front brakes by a right foot pedal to the left of the accelerator pedal. Tyres are Avon slicks - usually 8.2/20-13 front and rear - in soft "hillclimb" compounds. Weight is around 325 kg.

The engine has evolved from the troublesome carburetted 1510 cc to a fuel injected 1380 cc Civic engine with Motec EMS, but doesn't seem to have lost any power.

This car and the Colliers' Renault special are currently (in 2008) the fastest motorkhana specials in Australia. Wayne sold the car to Bruce Antaw in late 2004 but has, with Bruce, continued to maintain and drive it.

Wayne won the Australian Motorkhana Championship (AMC) in the Terrier in 2002 and 2006 as well as winning the NSW Championship in 2004 and sharing it with Andrew Collier in 2003.

 

  The Renault Special driven by Andrew, David and Sam Collier was built by Andrew, David and their father, Bruce, in 1998. It features a light spaceframe and fabricated independent suspension by wishbones and coil-over-shocks all round. The all alloy engine is from a Renault 16TS, bored and stroked to just under 1800 cc with modified head, a Haltech controlled fuel injection system, custom exhaust and numerous detail modifications. The transmission is a Renault 17 automatic, much modified with the gears apart from first and reverse removed, gear change is by solenoids controlled by a toggle switch on the top of the fiddle brake lever.

Front and rear disc brakes are a combination of Renault 16 rotors and Renault 12 calipers, while the wheels are 13" composites manufactured in house by the Colliers. Tyres are Avon slicks - 8.2/20-13 front and the 9/20-13 rear - in soft "hillclimb" compounds. The radiator is transversely mounted at the rear. Weight is around 400 kg. A selective rear brake ("fiddle brake") operated by a lever on the driver's right locks either of the rear wheels to start a rear slide or, used more gently, reduces understeer.

This car and Wayne Griffith's Terrier special are currently (in 2008) the fastest motorkhana specials in Australia. It and its predecessor have won 10 NSW Championships and the 2007 AMC for Andrew and the 2006 AMC for David Collier.

 

Alan McConnell's Mini Special was built by Alan's father Keith in 1986. It featured a light spaceframe and fabricated independent suspension by coil-over-shocks all round. This was a departure from the usual Mini special setup of Mini front subframe and front suspension with a beam axle at the rear and saved considerable weight. The rear suspension was similar to that of the Delta SS below. The engine was Morris 1100S bored and stroked to 1435 cc with worked head (by Keith), Weber 45DCOE, Ivan Tighe 140 cam, custom exhaust, lightened flywheel. The gearbox was 4-synchro Cooper S with "straight shift" driving a Salisbury LSD.

Front and rear disc brakes were lightened Morris 1100 while the wheels were 13" Simmons composites. Tyres were various Avon slicks - typically 10/20.5-13 front and the same or 8/20-13 rear, initially in medium compounds but later in the softest available compounds. The springs were stiff to keep the wide tyres well planted. The large radiator was transversely mounted behind the seat and had no fan. Weight was around 330 kg. As well as the pedal for the rear brakes, a handbrake was a later addition for tests where a gearchange from forward to reverse had to accompany a rear brake initiated spin (a rear throw).

This car and Wayne Skyring's Mini special both employed LSDs, wide tyres and stiff suspension successfully and by the end of the 90s, most other leading Mini specials had moved in the same direction.

The car won six AMCs for Alan in 1989, 90, 94, 97, 99 and 2001 and also won numerous Queensland championships. The car was sold to Phil East in late 2003 with Globe alloys replacing the Simmons wheels. Phil shifted the seat forward, added a cooling fan, reversed the gearchange and shifted the battery forward from between his thighs.

 

Bill McCarthy's Delta SS, shown in Ipswich, Queensland in 1982, was built by Peter Tucker in 1979/80. It featured fabricated independent suspension all round by wishbones at the front, upper wishbone and lower 3 link at the rear, coil-over-shocks all round. A Subaru 1600 engine with automatic transmission fed 155/450-10 Dunlop wet compound slicks on 10" x 5", 5.5" and 6.5" wheels. The four pedals were, from the right, accelerator, front brake, front brake and rear brake - the left front brake pedal mostly used for restraining start line auto creep. The engine was improved by the usual Weber 45DCOE carburettor. It weighed 350 kg in 1982. The roll hoop was raised and thickened after the above photo was shot. The car was handicapped by the complex steering system which had to find its way over the transmission, and by taller than ideal gearing. The auto made gear changing on reversing tests much easier and quicker. Handling was inclined to be twitchy.

It was sold to Phil East in late 1986 and driven by Phil, Corinne and Lauren East. During Phil's ownership, the original coil over shocks were upgraded to Spax front and Koni rear.

It was repurchased by Geoff Thomson and Bill McCarthy in 2002. In the next couple of years, they altered the steering geometry a little, changed to 13" x 7" wheels and tyres, and had the heads shaved and ported by Brian Pope of Link Automotive to compensate for the taller gearing created by the 500 mm diameter tyres. Various suspension improvements helped the handling but it was still twitchy.

The car's major wins were: Australian championship in 1981, 83, 84, 85, 86 driven by Geoff and the Victorian championship in 1981 and 82 driven by Bill. Corinne East achieved 3rd outright in it in the 1994 AMC, the best ever AMC placing by a woman. Geoff came second in it in the 2003 AMC. It was sold to Jim Newell after the 2004 AMC.

 

The Delta S, shown in Adelaide in 2004, was built in April and May 1977 by Peter Tucker for Bill McCarthy. It was intended to be a lighter, better suspended and powered development of the concept pioneered by Rob Mutimer's Mini Special.

It started with a 1310cc Cooper S engine with Weber 45DCOE carburettor, worked head, Wade 240 cam, "straight shift" Mini 1100 gearbox with 3.44 diff, lightened Mini dry front subframe with light space frame attached, central seating and steering, Cooper S front disk brakes, rear drum braking by a fourth pedal to the left of the clutch pedal. It had a uniquely mounted rear beam axle with two double diagonal links with a central roller in a vertical track, and Honda 750 coil over shocks with shortened springs. All suspension joints were ball joints or rodends. At the front, springs were rubber and shocks were Koni. Another driver aid was the column gearchange with straight up for forward, straight down for reverse. This was made practical by the "straight shift" gear selectors designed by aeronautical engineer Neil Pollock.

On bitumen in 1977, it used 10" x 5" and 5.5" Minilite wheels with 155/450-10 Dunlop ungrooved wets front and 165/70-10 road tyres rear and weighed 320 kg. Extra panelling, slicks on the rear and two 10" x 6.5" Head Mod composite wheels at the front took it to 330 kg for 1979.

After Ross Whitbourne bought it in late 1979, he fitted a 13" steering wheel, 10" x 8" chromed wheels and 200/450-10 tyres and a mild LSD, tidied the master cylinder setup and increased the engine response with lighter flywheel, more compression and better manifolding. David Beames acquired it for 1982 and progressively upgraded it, adding a bonnet and converting to 13" wheels. Its tyres are now ungrooved 9" soft Avons or Dunlop wets on 13" x 8" alloys at the front and grooved 170/500-13 Dunlop wets on 13" x 7" alloys at the rear and it weighs about 350 kg.

The car won Bill the Victorian Championship in 1977 and 78 and the Australian Championship in 1977, 78 and 79. Ross took it to second in the AMC in 1980 and 81. David employed it to win the SAMC in 1982, 83, 84, 86, 87, 88, 92, 95, 99, 2001, 02 and 03 and the AMC in 1991, 92, 95, 96, 98 and 2003. With 14 state and 9 national titles, it is the most successful motorkhana special to date (2008).

 

Terry Goodacre's Subaru special, built in 1974, is shown in 1976 form with bonnet added. A quite standard Subaru 1400 engine with manual gearbox was mid-rear mounted. Terry built the spaceframe around some bulkheads intended for a Formula Ford. The front suspension was narrowed VW Beetle, the rear was by three very short lateral links and two trailing arms with coil over shocks. The front roll hoop was unique among leading motorkhana cars. It had the usual, for RWD specials, "fiddle brakes" - a push-pull lever operating one or other rear brake - which enable the car to be slid controllably under power. On both dirt and bitumen, the tyres were grooved 13" x 7" front and 13" x 9" rear Dunlop racing tyres on steel rims. Due to the tyres and no more than adequate power, the car's traction was outstanding on all surfaces.

Championship wins in Terry's hands were Australian 1975, 76, NSW 1975, 76, Victorian 1976. It was sold at the end of 1976 to John Woolcock and later, I think, to Mike and Anne Hayward. It had some maintenance issues by then and faded away.

 

Rob Mutimer's RWM Mini special, shown in its early 998cc form at Northland Shopping Centre in Melbourne's North, was built in 1974. This car led the Victorian FWD special charge which set the format for most top-level specials for 30 years. It started with Mini engine, gearbox and front subframe with light space frame attached, central seating and steering, unique unsprung, centre pivotted rear axle and rear braking by either a hydraulic handbrake or a fourth pedal to the left of the clutch pedal. It later gained a transverse leaf sprung rear beam axle, 1310cc Cooper S engine with Weber 45DCOE carburettor, "straight shift" gearbox, lowering and lightening. Its weight then was estimated at 350 kg.

The car won Rob the NSW Championship in 1977, the Victorian Championship in 1979 & 1980 and the AMC in 1980. It was then sold to Arthur Latta, then went to Wayne Griffiths from 1983 to 1993 during which time almost everything except the basic layout was altered, including an engine change to 1380 cc. It then went to Robert Budniak for some years before finding a home with Warwick Butt in 1999. With the engine now grown to 1430 cc, Warwick won the 2004 AMC and the 2007 NSWMC in it.