It's time to accommodate the main man - the all-important driver...
GT40 Tribute: DIY SUPERCAR
Welcome back into the Roaring 40s shed, where we’ve been building up what amounts to a low-flying missile – a tribute GT40 – at something less than a tenth of what a real 1960s version would set you back. They’re a no-holds-barred sports car, though there is still a little room to customise the car to suit your own tastes with different engines, brake packages and a host of details.
Last issue we managed to get the chassis up on a set of shop wheels, and settle in a few major components, such as brake calipers and suspension arms. But there was still nowhere to sit and, as a whole, the ‘car’ was looking more like something feral that escaped the Meccano R&D department, rather than something you might actually get to drive on the road.
This time around we’re tackling stage three of the build, namely getting the driver settled in and attaching the bulk of the gear that carries fluids.
TAKE A SEAT
Right from day one, when we were first ordering the start of the project, the good folk at Roaring Forties need to get a little personal. This is, after all, a design based on a race car, so cabin space is at a premium. So if you’re very tall, that needs to be allowed for in the initial chassis build.
Almost anything is possible, such as a lowered floor pan, so long as you plan ahead. “The seats come with adjustable runners,” explains Adrian Sorensen of Roaring 40s, “but if your sitting height is critical, deleting those runners buys you back an extra 40mm or so of head height. Of course another option is to allow for this in the earlier chassis stages, via a lowered floor.
“We would have established the seated height of the client right back before phase one at our initial prefabrication of the chassis.”
By this point we’re down to fine-tuning the driver position. Sorenson says it all centres around the steering wheel. Apart from having a little room for height adjustment, it goes into a fixed position. “We put the steering wheel in and, longitudinally, that is a fixed point in space, because it’s not telescopic,” he explains.
Next, the seat is rolled in and its position is dialled in so you have the correct arm position – you’re not even thinking of legs at this stage. So, what is the correct position? Sorensen says that’s entirely up to you – after all, the whole point of building a car is you can suit it to your own tastes.
Next, the pedal box is introduced. Like the seat, it has a range of positioning available, so you should be able to get the reach and angle just so. “Normally people think adjustable seat for my legs,” says Sorensen, “but because the steering wheel doesn’t move and both the seat and pedal box are modular, you move the seat to get the arms right and the pedals to get the legs right.”
We’ve got the steering wheel, seat and pedal box in, we can now mount the shifter and you have a choice between central or right-hand mounting.
“Because it’s a nice self-contained module with two cables coming off the back of it, there’s a bit of freedom for exactly where you position it on the right-hand-side. The shift is an H-pattern, with a reverse lock-out so you don’t actually snag the wrong gear when you’re going for first. It was developed in-house.”
The last thing you come into contact is the centrally-mounted handbrake, which completes the rear brake package.
FLUID MOTION
Now it’s time to tackle the plumbing for fuel, coolant and hydraulics. This is where you fold up all the solid brake and clutch lines and mount those to the chassis, and mount them to the braided flexible lines that, in the case of the brakes, attach to the calipers.
Bending the solid hydraulic lines and flaring the ends for mounting to a hose is something of an acquired art. It’s something that will be rewarded by a bit of practice on a spare piece of line, before you start the job in earnest. Sorensen points out, “An area of critical importance is the solid brake and clutch lines, particularly the brake lines. You don’t want to work and rework a line and potentially fatigue and create a hairline crack in solid lines.” So the message is to get your head around the technique and don’t be afraid to ask for help.
We’re also doing the generic cooling system for the car, which includes the radiator, the cooling fans and the coolant pipes that run up the centre of the chassis. Then, later down the track, when you’ve chosen your engine and put it in, that’s when you buy the specific supplement system.
Fuel is carried by two precision-welded fuel tanks, under the sills, adjacent to the cabin. Total capacity is a very substantial 87 litres. “In the new fuel system, the tanks now cross-feed and we’ve only got one pump in the right-hand tank,” says Sorensen. “The old way, the right-hand tank was partitioned and there was a sealed section fed by small lift pumps, and then a high pressure pump drew from the rear section and fed the fuel rail. Very complicated, and then you had to have two fuel gauges and a switch on the dash to select the feed, (he rolls his eyes…), it was a nightmare.
“So now there are just two tanks, with a nice pre-bent crossover pipe, and the in-tank pump is in its own cylinder – serving as a swirl pot.”
About now, you might be wondering if there are instructions for all of this – the answer is yes, there is. “We’ve got a very comprehensive construction manual. Because so many changes have been made to the car in the last few years, we’re in the process of completely rewriting it,” says Sorensen. It’s computer-based, which means owner/builders can be sent the very latest upgrades as they happen.
If you find the whole idea of bending solid hydraulic lines a bit off-putting, Sorensen offers a solution: “Get us to do it.” In fact, Roaring 40s reckons it can offer a massive jump start to your project by doing much of the initial assembly, up to this stage. “What we’ve done for a couple of clients recently, is we’ve done the panel-fit for them and the solid brake and clutch lines and got the car to a rolling state, and then shipped it off to them. It’s sort of like a par-built car, still way less than the 49 per cent that we’re allowed to,” explains Sorensen.
“What it does is it alleviates the concern of doing something that’s safety-critical and if they’ve not done it or had experience with it, it could be very daunting. That’s something we’ve been doing recently and we’ve now got two cars on the go downstairs.
“It’s a great incentive to keep going because it actually looks a bit like a car by that stage. The beauty of it is if they’ve got us to do the panelling, then it’s a matter of getting a box of shiny new bits and bolting it on – so there’s instant gratification.”
Last and far from least is the air-conditioning system, which Sorensen says is a very straight-forward task. Air in a race car? Well, apparently it’s a necessity, as the combination of a small cabin with a big slanted windscreen one end and a big throaty engine the other, can get a little warm on a summer day. Last on the list is the wiring loom, which the crew at Roaring 40s swear is idiot-proof. “Everything is labelled,” says Sorensen, “and the way the connections are set up, it’s impossible to get them wrong.”
It’s essentially just one loom, regardless of the engine chosen, and it supports a dash that includes speedo, tacho, fuel level, oil pressure, water temp volts and clock.
What about a sound system? “That’s taken care of by the engine and the squealing passenger,” says Sorensen. Fair enough…
Photography: Stuart Grant