Before we explore those issues, just a little history on the Cortina bodyshell. This event goes a long way to identifying why it became critical for the Tech boffins on both sides of the ‘go faster’ fence to morph into what we today know as race engineers. Race engineers being those unique folk who have the training & talents of factory engineers as well as the built-in experience and knowledge of racers. People who in today’s world are in my opinion among the smartest tech folk on the planet.
Back to that bodyshell…The late 50’s and early 60’s introduced a new era of unitary body construction by most manufacturers. The removal of a heavy chassis which was the norm previously, required that some smart tech went into ensuring that the new monocoque body shells could handle the attachment of suspension and drivetrain components directly to the structure and do so durably. The obvious advantage of these new designs would be the significant weight and cost reduction and as we learned later, provided a much more solid feel to cars by removing the ‘wobbly’ bits connecting the old-fashioned chassis arrangement. The Cortina development went a step further and Ford Dagenham had the foresight to employ an experienced aircraft structural engineer specifically tasked with optimising the Cortina bodyshell to arrive at the best combination of strength, rigidity and weight.
It is also little known that in the early 60’s both Ford UK and GM’s Vauxhall were under pressure to adopt front wheel drive packaging…in Ford’s case from the mothership…and a front wheel drive design out of the USA on the cards for the Cortina build slot. VM UK had also completed such a design for the first Viva.. The new FWD designs offered the now well-established advantages of packaging, cost and weight over the conventional rear wheel drive applications. Both companies were dealing with the evolutionary pressure at exactly the same time.*
Thankfully for us enthusiasts and partly as a result of the good work done by the body boffins, the decision went the RWD route for Ford Dagenham, resulting in the Cortina making it to production. The work done on the bodyshell was exemplary and resulted in the original 2 door base model 1200 Cortina weighing in fully built up at around 750 KG. This is significant because the Cortina’s little brother the Anglia came in at a relatively portly 739Kg. It is said that there was ultimately no sheet metal in the Cortina shell not doing its job…. an ideal basis for the Lotus Version…
However… you will recall that comment in the opening piece where I mentioned the two schools of ‘go faster’ thought contributing to these ventures. In this case, Chapman had his own ideas and pushed for changes to the rear suspension of the car to accommodate his ‘A’ frame coil spring design, similar to that used on the Lotus ‘7’. (His original idea was to go to a fully Independent RS but had that plan denied after giving the Ford engineers a collective heart attack) The ‘A’ frame design change required extensive reinforcement of the floorpan and the whole thing added to the weight of the car and torpedoed some of the diligent work done by our aircraft structural engineer in the first place. This was the type of lesson to be learned by the ‘hot rodders’ of the era simply because a rational, properly engineered solution could have happened at the start of this project…if the teams were on the same wavelength and pooling knowledge. As we will cover in this story, it took two years to correct a problem resulting from this design change..
At the start, Lotus Cortinas were equipped with aluminium skinned doors, bootlid and bonnet as well as the lighter dual front bumpers sourced from the rear items on the Anglia panel van. These parts offset the increased weight of the Lotus version to a degree (extras further included sidedraught carburettors, brake booster and trim changes) over the 2 door 1200 on which the car was based, however … the FIA Lotus Cortina Homologation docs show the original at 850Kg. This was soon paired down to 812 Kg at the start of the 1964 season but strangely the documents do not highlight the detail of this 38Kg diet.
* The VM decision also went to rear wheel drive for the first Viva and in that instance, Vauxhall decided to use the RWD option they had designed in parallel with Opel for the 1962 RWD Kadett)
Further to this and as is normal practise in order to minimise the probability of problems in the field, car manufacturers diligently cross the T’s and dot the I’s as best they can during development of a new product. The Lotus Cortina did not follow that path…this was a pressure cooker project and with 1964 0n the works race horizon, the homologation job had to be done pronto. Much of the design work was being done by Lotus, the extensive testing of revised designs did not happen as thoroughly as it should have and because the final vehicle build was carried out at Lotus, traditional production standards were not fully applied. The car suffered from a number of significant technical issues. These resulted in problems as basic as rust, as well as that coil sprung ‘A’ frame rear suspension durability problem.
The close ratio Elan gearbox was also an issue – first gear was too tall for puttering around town, with gradeability in 1st gear and clutch wear generating some owner resistance. In hindsight this was hardly surprising given the ethos of a properly geared performance car not being too well understood at the time. The Twin Cam Elan engine destined for the Cortina had also had a difficult gestation and ultimately the Cosworth team had a hand in tidying things up with that revised cylinder head arrangement. Did all that matter in the final analysis?…. Not at all. Despite the difficulties and a clearly flawed product, the concept just took off. Entrepreneurial spirit triumphed over conservative logic…… that sort of thing could work in the 60’s.
The relationship between Ford and Lotus did however, become strained because of all this and the rear suspension issue caused a rumpus between Ford Engineering and Chapman. … As things play out however, these mistakes eventually resulted in more effective development rules being established between the tech gurus in the respective ‘Hot rod’ and OEM engineering camps.
This is just how things happened in this turbulent but productive period..
So Ford upgraded and fixed as they went along, the rear suspension reverted to leaf springs, but only after back to back track testing showed the change to be OK and a return to that structurally good shell and associated weight savings. The gearbox was changed to that of the new GT ‘box (originally fitted to the Corsair GT) with more widely spaced ratios getting that first gear into a mode more acceptable to Mr Average…. and all was forgiven.