Home Page - Building Your Own GT40 MkI/II Chassis

Author & Designer - Mike Osborne (November 2011)

Why would you want to build a chassis for yourself instead of buying one off the shelf from a main line manufacturer? Well most people would probably be quite happy with a standard well tried chassis from a reputable manufacturer and why not.
Well there are several reasons that come to mind not least of which is the cost, use of better lighter modern materials which could be used but are almost certainly not used in an effort to cut costs to a minimum, there are also improvements which could be made to comfort, braking and handling, which would not distract from the appearance of your car but would greatly enhance handling, safety and performance.

This article and the drawings I’ve produced over the last 7 years or so goes a little further in the quest for accuracy and improvement on the original design in the form of more rigidity, better handling, more flexibility in what engine can be used i.e. 4.6 litre quad cam Ford 32 valve engine with injection and cat converter to keep the authorities happy or the original 302 or 351cu inch units, as for the  gearbox there are several more modern transmission units now available which are stronger and better suited for high performance machines being able to take standard limited slip differentials etc and are almost certainly cheaper than the standard Renault 21 turbo box which is becoming harder to find and more costly, these more modern transmissions like the Audi 5 or 6 speed transaxles won’t wear out like the Renault units which were never designed to take V8 power.

Figure 1 (above): GT40 MKI / II rolling chassis ready for its bodywork & engine/transmission.

The chassis is designed to take up to 500bhp and 500ft. lbs of torque with either 4 dual barrel downdraught carbs, weber or motec injection, AP road or racing clutches, Willwood or Brembo 14" vented disk brakes with 4 or 6 pot alloy calipers, balance bars to the twin master cylinders, pressure residue valves and twin servos connected to a dual braking system for safety.

The rear of the chassis is designed to accept either Renault 21 Turbo, 25 or Audi 5 or 6 speed boxes though others will fit if so desired. The front and rear body mounts allow for the removal of the body panels in under a minute using the original roll off / roll on Ford system used on the Le Mans race cars.

Fuel tanks (one in each sill) can be foam filled and are designed to take from 18 to 35 gallons (80 - 156 litres). Swirl tanks are recommended for the fuel delivery system and twin red top fuel pumps if the engines are tuned or the car is to be used on the track.