The Big Car Database


The Grinnall Specialist Cars Ltd. ( Grinnall Cars) is an automobile and motorcycles maker founded by Mark Grinnall in United Kingdom. This company mainly produced three-wheelers. It is based in Bewdley, Worcestershire.


In the beginning, Grinnall Cars started to modify Triumph TR7 cars. By 1990 they produced 350 units of Grinnall TR8 based on Triumph TR8. In 1991 Grinnall started to produce three-wheelers (also known as Trikes). In 1992 they started Scorpion III development. In 1998 started Scorpion IV development.

Production list

  • TR8
  • Trike 1200C/CL also known as Trike I.
  • Trike 1150R also known as Trike II.
  • Trike R3T
  • Scorpion III
  • Scorpion IV

The company's reputation was first made by its extensively reworked and refined conversions of the Triumph TR7 and TR8. By the early 90’s some 350 Grinnall TR8s had been constructed. In 2006 The Triumph Register acknowledged the Grinnall TR8 as a marque in its own right, and has compiled extensive history files on the vehicles.

New concept needed

In 1991, in search of a radical but affordable high performance concept, Mark Grinnall turned towards his passion for motorcycling, and his hand to an innovative three-wheeler, which unlike any of its illustrious ancestors would be high-tech, mid-engined and rear wheel driven. This was to be the first in a family of unique, niche-market sporting vehicles. The Scorpion-III made its debut in 1992 when it was featured in CAR magazine, an article written by a young Colin Goodwin. Interest in the S-III exploded in the mid 90’s, with the breathtaking featherweight being featured in dozens of magazines worldwide.

The S-III is still in production over 20 years after its launch. This is testimony of the design quality and pleasing aesthetic. Using an online Yahoo social forum a global network of owners share their interest in the cars and experiences, with organised events and tours in the UK, Europe and the US. Trouble shooting discussions develop and an archive of history has been compiled to assist owners with cars some of which are over 20 years old. Full factory back-up guarantees all parts and service are available for machines new and old.

The latest S-III model features the state-of-the-art BMW 1300cc 4-cylinder motor from the K1300S motorbike. With 185bhp, wider track, billet uprights, stiffened rear suspension and many other new features, this machine is lots of fun and very rapid. With 460bhp per tonne this little cycle car is guaranteed to upset Ferrari drivers, and can still return over 50 miles per gallon.

The next stage in the company history was to create a four wheeled version of the S-III, to be called the Scorpion-IV. Development of this new car began in June 1998. Research had confirmed the plan was the right one.  At motor shows and demonstration days up and down the country at BMW Motorrad dealers - and via our website - a significant number of prospective customers, and some Scorpion-III owners too, had been asking us to produce a four-wheeler. They wanted a little more interior room, and even more performance, mainly for the growing track day market. Since that time, several more vehicles destined for this niche have appeared – and some have disappeared. Possibly one of the most successful arrivals is Simon Saunders' skeletal Ariel Atom.

Scorpion-III designer Steve Harper (SHADO) was again commissioned to style the S-IV to the same ‘form follows function’ design brief, and maintain a clear family relationship between the two.

Findings from the research and development of the highly-acclaimed Scorpion-III went into the building of the new Scorpion-IV chassis; a space-frame structure which is remarkably rigid, yet respectably light. The front suspension is a development of that which works so well on the Scorpion-III: Unequal length double wishbones in oval tubing with inboard coil springs over custom made gas dampers, with adjustable camber and castor.  At the rear, long, super-stiff longitudinal links give superb handling and now feature a top link to give camber control. The key here is the vehicle's distinctive styling was never compromised.

Exhaustive trials of possible power-trains were carried out to find the best power train solution included the Rover V6 K-series, Honda 2.0 litre VTEC and Fiat 20v turbo - all fine products. Eventually however, we decided to use the incredible Audi/VW 20v turbo unit, which makes 225bhp in standard form and up to 500bhp after the tuning wizards have done their stuff. The slick Getrag 6-speed gearbox compliments this superb motor perfectly.

In 1999 work began on the first of our motorcycle derived moto-trikes – with a single front wheel. For us the obvious starting point for a great trike was the BMW R1200C – a machine that had the twin advantages of BMW’s tele-lever front suspension and shaft drive. Launched in 2000, this has been a constant seller.

To the Grinnall Trike collection were added the BMW R1200CL, the Montauk, the sportier R1150R, and in 2005 the Triumph Rocket 3 based trike - the R3T. This has been a wonderfully successful machine, and makes probably the best moto-trike on the planet. Continuing with Triumph a new moto-trike will soon be launched based on the fabulous Triumph Thunderbird 1600 and 1700. This new machine will herald the beginning of belt/chain driven trikes to be rolled out of Grinnall's R&D department in the future. 

In 2013 we purchased a 2 acre former agricultural site on the outskirts of Stourport-on-Severn, Worcestershire (post code DY13 0TF). 

The new site will allow the expansion of our moto-trike range, and finally enable full production of the Scorpion-IV. Re-organisation and production conformity will also allow us to comply with EU regulations and thus EU Certification of Conformity (COC), opening up huge sales potential within the EU. Neither production of the S-IV nor COC for the 3-wheeled vehicles were possible from the old site.


Scorpion III - K40

The latest Scorpion III is powered by the amazing BMW 1200cc and 1300cc K-series engines. Power outputs are 170bhp and 185bhp respectively, giving the little S-III a power to weight ratio of over 460lbs/ton.

The latest motor signals a break from tradition for BMW, as it is transversely mounted like most Japanese motorbikes. The centre of gravity is very low which improves safety at higher cornering speeds. The new motor also has a dry sump, which eliminates oil surge.

There is now a choice of engine management systems. The Grinnall option eliminates the use of the CANBUS system used by BMW. Our plug-and-play system is very simple to install and it’s no longer necessary to connect the BMW computer for the engine install or servicing.

Handling is sharpened by a new wide-track front footprint (120mm/4in wider), that uses new aluminium billet uprights. Steering feel is improved with a new adjustable steering column which is fitted with sealed needle roller bearings.

The S-III is now offered in the latest colours including MICA paints and bespoke custom paint jobs.

Scorpion IV – production re-starts in 2015

This fire breathing monster was mothballed for several years due to lack of factory capacity and the resounding success of the R3T trike. However, the move into new premises in the spring of 2015 will enable production to re-start. We are currently developing a revised S-IV rear suspension that alters the rear camber in corners, thereby improving rear end grip.