Granny Smith Racing Mini Marcos

Bodyshell

Standard Mk4 Mini Marcos fibreglass monocoque with modified rear arches and removable front end, rear diffuser starting from rear subframe mounting face and extending to rear of car. Front end, bonnet, diffuser and rear arches designed and made by Pete Crudgington. Roll cage supplied in kit form by the Rollcentre. Fibreglass is 6 to 10mm thick resulting in a weight of 593kg without driver. The car is not a spaceframe but a fiberglass monocoque fitted with a 6 point cage.

Motordrive clubmans seat and 4" wide OMP seatbelts.

Suspension

Front: AVO coil overs mounted in modified sub frame, modified low arms and modified standard tie bars. Modified uprights using Mk1 Metro lower ball joints to position front rollcentre 1" above ground. Standard steering rack with steering arms repositioned to reduce bump steer.

-0.5° camber, 8° caster

Rear: Spax coil overs, Metro rear arms mounted with rose joints on a Pete Crudgington designed and made subframe.

-0.75° camber.

Brakes

Front: Metro 4 pot Iron Calipers and standard Metro Vented Disks, DS3000 pads used for races, EBC green stuff for sprints.

Rear: Minifin ally drums with standard cylinders and shoes.

Standard master cylinder is used with an adjustable pressure limiting valve for the rear cylinders.

Engine

1380cc A-series, full race head with 37mm and 31mm valves by Billy McMillan formally of Nick Stagg engineering, Omega offset bowl forged pistons, lightened Metro rods, wedged, cross drilled and bladed crank, Kent 310 scatter cam, 1.5:1 full roller rockers, ARP fasteners used through out. Aldon yellow distributor with ignitor and Lucas sports coil, Dellorto 45 on 7" Maniflow inlet, large bore Maniflow LCB with modified 2" Maniflow system that exits through the rear panel. All built by Ollie Howell of O S Built Racing and set up by Dave Young at MechRepairs.

Gearbox

Jack Knight 4 speed dog box with Jack Knight Mk6 LSD and Jack Knight drop gears. 3.93 final drive used. Hardy Spicer inner couplings with OS Built UJ's, fabricated extra large driveshafts and Allegro 1500cc CV joints. All assembled with ultra high melting point Redline synthetic grease.

Cooling

Standard Metro radiator and 13 row oil cooler.

Wheels & Tyres

Dymag 8" x 13" wheels adapted to fit car with Dunlop 180/490-13 slicks with a softer compound run at the rear of the car. Avon slicks are used for sprints.

Instrumentation

AIM Mychron 3 Gold dash and data logging system, records speed, rpm, cornering g, oil temp, oil pressure, water temp, lambda and lap time.

Performance

Maximum speed on present gearing: 126mph.

Maximum power: 130 bhp (flywheel)

Maximum torque: 102 lb.ft

0 to 60mph: 5.8s

Standing quarter mile: 14.4s, reaching 101mph

Typical cornering ability 1.2 to 1.4g depending on speed and circuit.

Lap times: Silverstone 1:07.1, Castle Combe 1:17.6

History

Car was purchased in 1988 as a road car and used in this form until 1994 when it was fitted with a roll cage and arches were added, it then became the "Granny Smith Racing" Mini Marcos due to the VW Apple Green paint and the white apple on the bonnet. Competed in sprints and hillclimbs in road going classes before moving to the modified class in 1998. Car has gradually evolved to current spec over the last 10 years of competition.

Acknowledgements

All photos by Pete Crudgington and Ron Howell.

Thanks go to

Ollie Howell, OS Built Racing
Coombend Auto Electrical
Julian Howell and Dean Robertson
John Weeks, Little Dave
Sarah Levics, Mike Taviner
Monty Sadler, Ron Howell
Dave Young at MechRepairs
Wives and Girlfriends of all the above
Daniel and Kevin at Jack Knight Developments
MasterCard and Visa

Open the link on any photo to see a larger image.