Building the car took almost 1,000 hours between October 1997 and March 2001. Probably the same number of hours again was spent problem-solving and sourcing parts. That took me up to the stage that it was fit to be presented for the SVA test - but it still did not have a windscreen, wipers, washers a roof or a floored luggage space. (It is acceptable to submit a car for the SVA in this condition.)
If I had stuck strictly to the plans in Ron Champion's book "How to Build a Sports Car for £250" the build-time would have been much shorter. But all the changes I had to make because I used a Ford Sierra donor (which necessitated a 100mm widening of the chassis) added a lot of extra hours.
Also, a Sierra donor meant a far greater element of trial and error and, to a considerable extent, the car was redesigned, not by measurement and planning, but by the "it fits where it touches" methodology.
My aim was to use as much as possible from the Sierra donor to avoid problems caused by mis-matching components from a variety of donors. Only where a Sierra part was totally unsuitable, did I replace it with an alternative.
Another reason for widening the chassis was to accommodate a pair of aluminium bucket seats that originally came from the cockpit of a scrapped Royal Canadian Air Force Beech C-45 aircraft. I had "saved" the seats in 1972 when the aircraft was destined for destruction in Heathrow's fire training dump. The seats had been in another car I built in 1971 and I was determined to reuse them in this car.
The main parts imported from elsewhere were: steering rack (Escort); front hub carriers (Cortina); radiator (Volvo 340 1.6L); exhaust (Megane); silencer (Golf); Mirrors (Fiesta).The main variations to Ron Champion's design were -
The Pinto engine is a large and heavy (and some say useless) lump of metal. At the time I was building, there were doubts about it fitting into a 7 frame because of its height. It does fit without any of it sticking through the bonnet provided you (a) position it low enough and (b) get the heights of the scuttle and the nosecone right. Also, if you get the positioning right (back of the engine block 25mm from the bulkhead) the gearstick appears naturally out of the tunnel right where you want it to be - without the need for a remote extension. Reducing the depth of the sump by about 40mm also helps ground clearance.
If you are worried at all about the weight of your car, you would be wise to avoid my solution to the rear suspension. The traditional rear suspension is a live axle on trailing arms with a Panhard rod. A relatively lightweight set-up. However I couldn't see the sense in throwing away the Sierra's rear subframe complete with springs and shock absorbers and differential. 6 bolts hold the whole lot in place. So that's what I used. The springing is just right and the main penalty is the weight. Handling probably suffers a bit too - but as I have no intention of throwing the car round a track that's not too much of a problem.
If you make your chassis 46" wide, you'll need something like the covers shown in this photo to obscure the front ends of the rear subframe.The Pinto engine's exhaust and alternator are on the offside. These, along with the offside engine mount, conspire to make life a shade difficult when it comes to fitting a steering column. It is possible to use the Sierra's steering column to connect the steering wheel to the steering rack (just!). But it takes three universal joints and some additional lengths of column (and a lot of patience).
Click on this thumbnail for the bigger picture.
I had heard that retaining the Sierra's servo made the car over-braked, particularly in the rain, (due to the car being lighter than the Sierra) and that the front:rear compensator was unnecessary. So I left both of them out. In my experience, without them, the braking effect is just fine and the balance is right (with the front brakes locking before the rear ones - just like they are supposed to).
It is customary for Lotus 7 clones to have a one-piece lift-off bonnet. This gives you the added pleasure of chasing after a large aluminium sail if you remove the bonnet in a wind. It might be a break with tradition - but a centrally hinged (and secured) bonnet seemed like a much better idea to me.
As the overall dimensions of the car are not the same as the Ron Champion drawings, I was unable to use, or adapt, off-the-shelf fibreglass parts (wings/mudguards and nosecone). I therefore formed these parts in fibreglass myself.
The standard position for the fuel tank is along the extreme rear of the vehicle. However, on my car, that space is dissected longitudinally by tubes on which the differential is mounted: so there's no room for it there. In any event, I wasn't very happy about a tank right at the back of the car in the event of a rear-end impact. Initially, as I couldn't decide where to put a tank with a reasonable capacity, I adapted a 20 litre jerry can.
Over the winter of 2001-2, this tank was replaced by a purpose-made 35 litre tank mounted as far forward as possible and in front of the line of the rear axle and differential. The plan was to replace it with a steel one, but attempts at welding two tanks (one attempt mine and the other a blacksmith's) failed to produce a sealed tank. The main difficulty was that the tank was to be no simple rectangular shape - instead, it was a sort of "saddle" shape, to utilse dead space above the rear trailing arms. A solution came when I read in an American homebuilt aircraft book the words "fibreglass fueltank". That was it - I could do that. Only problem was that the resin needs a minimum ambient temperature of about 18 degrees C to cure - and this was winter coming on. Only thing was to get on with other things and leave the tank till spring. All I needed for a fibreglass tank was fuel-proof resin, as I had all the other materials left over from making the nosecone and wings etc.Rather than follow what I had done with the nosecone etc, ie make patterns then female molds, the tank was easier made by cladding a Styrofoam plug in fibreglass, then gouge out the foam leaving, hopefully, a fuelproof tank.
This worked well except that, despite applying coat after coat of paint to the plug, I couldn't get a smooth surface on it (which it needed if it was to separate from the fiberglass). I then hit on the idea of wrapping the whole plug in cling-film (to which fibreglass doesn't adhere). So that was how I applied the fibreglass - on top of the cling-film. That worked OK except the cling-film sagged in places, giving the tank a rather bulbous appearance. But as it was going to be hidden away in the bowels of the "boot" area I wasn't too bothered about its appearance. If I was doing this again I would wrap the plug in brown parcel-tape (to which fibreglass doesn't adhere either) which would adhere better to the plug and would give a better appearance. Getting back to the process - once the tank had a sufficient thickness, I cut two 150 mm square holes in the top of it and pulled out the Styrofoam. Before resealing the holes I fitted baffles (to stop the fuel surging from side to side on corners) and 2 copper exit pipes. And there I had it, a fuelproof fibreglass fueltank.
In the photographs below, the left one shows the shaped Styrofoam wrapped in cling-film. The one on the right shows the finished tank, with a coat of black-pigmented resin on the outside - to make it look a little more presentable. It also shows the lengths of flexible fuel-pipe that connect the bottoms of the tank to a T-piece.
As the tank sits in front of the rear axle, the filler had to be moved from the back of the car to the side of it. This necessitated lowering the rear mudguards to create an area for the filler to be fitted (involving much head-scratching and measurement!)
With the tank in place, I could get on with the job of forming a proper "boot" where up till now had been an unuseable void.
The recommended design for the front mudguard mounts looked a bit flimsy to me - and I've since heard stories of them breaking up - with much resultant flailing about/departure of mudguards. So it looked like a job for some heavy metal. 10mm x 25mm bar certainly does the trick! There is a tapped hole ideally positioned on the Cortina hub-carriers and a brake caliper mount sitting waiting to have mudguard mounts bolted to them. (Replace the existing caliper bolt with a longer one to accommodate the thickness of the mudguard mount.) Make up a couple of patterns in lighter gauge steel or aluminium, then borrow someone's oxy-acetelene to get your bar glowing at the points you want to bend it, then batter it into the shape of your patterns. A little trial and error in shaping them will give you mounts that will definitly not fall apart. And, along the way, you've had another satisfying afternoon beating hot metal into submission.
Click on the picture to the right for a better view.
Finding a way to route the exhaust was among the biggest problems I faced. On the Sierra donor car, the exhaust turns directly rearwards and disappears along the transmission tunnel. On Lotus 7-type cars, it has to exit the side of the engine compartment and run along the outside of the car. Unfortunately, its natural exit route is already occupied by the steering column! To get round this, I fabricated a 2 into 1 pipe (from steel plate and the bottom of a Ford Fiesta front-pipe) and connected it to a length of Renault Megane pipe via a section of flexible - routing it round the steering column (just). One day, when I can afford it, I should probably have someone bend up one length that will replace the lot.