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THE CONCEPTION Powered By Docstoc
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THE CONCEPTION                                                                                                                       PART

MEV is well advanced on creating an                                            Bike engines
                                                                           weren’t even
exciting new track day car for 2007. Over                                  considered. “As a
                                                                           biker myself, I’m just
coming months, we’ll be taking an                                          not happy with the
                                                                           idea of a tiny
exclusive behind the scenes look at the                                    motorcycle clutch in
                                                                           a car with two
development of the newcomer and                                            people on board,” Stuart             Above: Computer generated
                                                                           comments. “They also result in a     image gives a rough idea of
serialising progress.                                                      Q-plate.”                            how the new MEV will look.
                                                                               In the end, the decision was
HAVING LAUNCHED TWO NEW              the Rocket, I want them to able       down to a choice of Fords thanks         Only once these dimensions
cars last year, it would be easy     to build it, register it and, if      to their massive tuning potential,   were known could the Rocket
for MEV to sit back and simply       they get the bit between their        and the Focus got the nod – not      begin to take shape. “You can’t
wait for orders to be placed. But    teeth and want to go racing,          least because of the fabulous all-   style the car and then try to fit
the relatively high overheads for    easily comply with 750 Motor          alloy Zetec SE engine. Donors are    everything in.” Stuart did have a
this new firm coupled with the       Club regulations.”                    plentiful (MEV sourced a             very clear idea of how the car
exclusive nature of the Trek 4x4         Two elements of the design        Category D write-off with just       would look, though.
and R3 sports car mean that a        brief were immediately                30,000 miles on the clock for            “I ride a Harley-Davidson
third new product is needed to       formulated by that decision. The      £1100), the transverse layout is     V-Rod,” says Stuart, “and I really
make a serious business case.        Rocket would have an integral         eligible for the 750MC series.       love the way they’re proud of the
Equally important is that there      roll-over bar made from 48mm          The rules don’t allow a              raw materials that have gone
should be no cross-over between      CDS tubing (to comply with MSA        north/south layout in a mid-         into the bike’s construction.” The
the three cars.                      regs), and the mechanical             engined car. Finally, the 1.8- or    Rocket, therefore, will be made
    Inspiration for the newcomer     package would be based around         2-litre units can be used by those   from tubular steel that will be
– known at this time as the          a 1.6-litre engine (to comply with    not going racing.                    fully on display. “The architecture
Rocket, a tag which may or may       750MC class regs).                        The very first task in           has to be interesting. It can’t look
not stay for production models –         Like MEV’s first two models,      designing the Rocket, once the       like it needs a body to hide the
came from the Donington show.        the Rocket would be a single-         mid-engined layout is decided,       chassis tubes.”
MEV’s MD Stuart Mills decided        donor kit car in order to keep        is to sketch a driver in place.          With a lot of the key decisions
to set about developing a track      build costs reasonable. A number      Then Stuart gets somebody to         made, MEV was able to tack
day machine.                         of 1600cc donors were                 sit in a seat with a steering        together the first prototype
    The first criterion he set out   considered. Rover was one, but        wheel and pedal box in the           chassis and get the engine in
was that the new car would be        uncertainty surrounding spares        relevant positions. These            position. As you can see from the
easy to convert from a track day     supply ruled that one out. The        measurements are then taken          photograph, that’s the stage
car to a race car. “A lot of guys    increasingly trendy Mazda MX-5        and offered to the sketch. From      Stuart is at now. By next month,
enjoy track days, which then         donor was also shortlisted, but       there, the wheelbase, track and      it will have progressed further
gives them a taste to go             discounted on the basis that it’s a   final engine position are            and, in the next issue, we’ll take
racing,” explains Stuart. “With      classic in its own right.             decided. “With a mid-engined         a detailed look at how it went
                                                                           car, I’ll work from the back to      from design sketch to the initial
Below: Prototype chassis has been tacked together to make                  the front, finishing with the        rolling chassis stage.
sure everything fits. We’ll bring story up to date next month.             position of the radiator.”

                                                                                                                The Story so far...
                                                                                                                 AT THE BEGINNING OF 2006,
                                                                                                                 nobody had heard of MEV.
                                                                                                                 By the end of the year, it
                                                                                                                 had two models in the
                                                                                                                 market. The Range Rover-
                                                                                                                 based 4x4 was launched at
                                                                                                                 Stoneleigh before
                                                                                                                 becoming the Trek after
                                                                                                                 customer comments were
                                                                                                                 taken on board.
                                                                                                                    At Exeter, the three-seat
                                                                                                                 Mondeo-based R3 sports car
                                                                                                                 made its debut. We haven’t
                                                                                                                 driven this one as yet, but
                                                                                                                 we’ll get behind the wheel
                                                                                                                 as soon as possible.

WHICH KIT CAR? FEBRUARY 2007                                                                                                                     41
MEV Rocket                                                                                                                        PART

Our behind the scenes look at the                                          unit, which also happens to be
                                                                           very affordable.
development of the new MEV Rocket deals                                         In order that Rocket
                                                                           customers don’t have to use
with the critical relationship between the                                 a modified steering rack,
                                                                           the wishbones are
front suspension and steering components.                                  designed to coincide
                                                                           with the length and                                        absorbers,
                                                                           layout of the rack.                                     Stuart took
IN PART ONE OF OUR STORY             degree, a great foundation.               Next up is the                                   into account the
on the development of MEV’s              The CAD sketch also lacked        upright, once                                    height of the
Rocket, we showed a                  the longitudinal tubes to which       again sourced                               chassis and decided on a
photograph of the first chassis.     the steering and suspension will      from the Hyundai.                     Protech unit that’s 12in fully
One point of interest is the car’s   mount. “I would rather design         With zero camber                    open and 9.5in fully closed;
distinctive outer chassis rails,     the suspension and steering           set, the adjustable top balljoint   anything bigger would need a
with a gentle curve running the      physically than by CAD,” says         allows positive or negative         higher top mount on the
full length. This is achieved by     Stuart. “It’s intricate work, and I   camber to be introduced.            chassis. The dampers will
using a CNC controlled section       prefer to have the parts in front         Meanwhile, the king pin         ideally be half way through
rolling machine, rather than the     of me.”                               inclination is determined by the    their travel when the car is
more conventional radius                 Indeed, the steering and          upright. At 7deg the Hyundai        static in order to have equal
benders used for roll cages etc.     front suspension were the first       unit will provide good self-        travel up and down.
Before the frame was tacked          things Stuart put in place. “You      centring – just what MEV needs          Once the ride height was
together, designer Stuart Mills      don’t want any compromise             for SVA approval.                   determined, Stuart could mount
sent a sketch of the chassis to a    here, so this goes in first and           Before fully developing the     the damper unit to the chassis
structural engineer.                 everything else will then fit         top wishbone, the castor angle      and bottom wishbone. After
    The chassis’ strength could      around it.”                           needs to be set. This is altered    that, it was time to test this
then be tested using a CAD               With the steering, it’s           by moving the position of the       high stress area of the chassis.
software package. As a               important to align the rack’s         top balljoint fore or aft.          The subsequent introduction of
consequence, the structural          inner balljoint with the inner            “With a mid-engined layout,     a triangular, 3mm thick fillet
engineer introduced two              bushes of the wishbones – vital       steering weight isn’t such an       plate into each side completes
diagonal members at the back         to minimise bump steer.               issue, so the Rocket will run       the design of the front end.
of the car – the result of which         After grubbing around in          with slightly more castor angle         Next month we’ll look at the
is a highly impressive torsional     salvage yards with a tape             than, say, a typical hatchback.”    back suspension – always a
rigidity of 4920ft lbs per           measure Stuart chose a Hyundai            When deciding on shock          tricky area for mid-engined cars.

Below left: Positioning of the rack is critical to dial out bump steer. The steering’s track control arm should be parallel with the
bottom wishbone, and remain as such throughout any suspension travel. The steering rack’s inner ball joint is offset from the
centre line of the top and bottom inner wishbone mounts, as shown with the left ruler. This mirrors the set-up of the outer
balljoints in relation to the track rod end. The latter is set to the right of the steering axis line shown by the right ruler. When
turning a corner, it means the inside wheel turns more than the outer – which it needs to because it’s turning through a tighter
radius. Camber is another critical element of steering feel. You can see that the top wishbone is shorter than the lower one. As
the body rolls during cornering, the top wishbone tracks a tighter arc than the lower one, thus altering the camber angle to
compensate for the geometry changes brought about by the body roll – the aim being to keep the tyre contact patch constant
by keeping the wheel vertical. Below right: Static adjustment of the camber angle is done by winding the top wishbone outer
ball joint in or out. Here a camber gauge is clamped to the brake disc and is showing 2 degrees of negative camber.

60                                                                                                             WHICH KIT CAR? MARCH 2007
MEV Rocket

The rear suspension’s now taking shape
and some of the basic body panels are
being moulded. MEV’s Rocket is coming
together nicely.

THINGS ARE MOVING ON NICELY       What MEV didn’t want to retain
up at MEV’s Nottinghamshire       was the standard MacPherson
workshops. Last month we          arrangement which is tall, heavy
looked in some detail at the      and lacks adjustability. So the
design and fabrication of the     basic design is a double
front suspension and, pretty      wishbone affair with outboard
obviously, before the Rocket      coil-overs (as per the front).
chassis could be dropped on       While a rose jointed location for
wheels, the rear suspension       the wishbones will also be
needed sorting.                   available as an option, more        Above: Focus Zetec SE engine being tried for size. Looks
    In order to keep the build    conventional bushing will be        perfect. Below: Rear suspension is a double wishbone affair
cost down, the rear suspension    the standard factory fitment.       utilising donor parts from the Focus in a fabricated hub carrier.
has been developed to utilise     “It’s important to remember
the bearings, hubs, discs and     that rose joints tend to wear          Packaging suspension              limited angle at which the coil-
calipers with handbrake from      relatively quickly,” comments       around a mid-engined                 over dampers can be inclined.
the Ford Focus donor which will   MEV’s Stuart Mills, “so I           configuration is often tricky, and   By its nature, every suspension
be providing the Zetec SE         wouldn’t recommend them for         on the Rocket one difficult area     design is a compromise, and
engine intended for the Rocket.   road use.”                          to overcome has been the             locating the coil-overs in an

64                                                                                                            WHICH KIT CAR? APRIL 2007
upright or heavily inclined
location will offer both
advantages and disadvantages.
More upright, and you can get
away with softer springs, but
may suffer shorter suspension
travel. A more angled location
may aid suspension travel, but
spring rates must increase and
loads on the suspension
components go up accordingly.
    For the Rocket, Stuart’s
confident that the set-up will
give good overall suspension
travel while not having to
introduce stiffer than necessary
spring rates. Certainly, going
too stiff can be a disadvantage,
with any benefits in reduced
body roll being countered by
loss of traction over more
uneven surfaces. “The all
important goal,” explains
Stuart, “is to keep the tyres in
contact with the road at all
times. Stiff doesn’t necessarily   been time to start developing    stage is to make a buck, from       chassis and the basic design
mean best.”                        the Rocket’s minimal             which a fibreglass mould can        given the green light, it was
    While the suspension work      bodywork. As with any            be made, and then final             then back to a stripped chassis,
has been ongoing, there’s also     fibreglass bodywork, the first   production panels produced          so that a chassis jig could be
                                                                    using the mould. The pattern        created around the prototype
Above: The project’s really gathering pace. Here’s Stuart trying    work to create the bucks            frame. Getting this jig correct is
the chassis for size. Below: Bonnet buck takes shape. Below         involves accurate measuring         important, because it will
right: One of the rear wheelarch bucks.                             and styling to form a basic         provide all the fixed reference
                                                                    shape from a combination of         points for the chassis fabricator
                                                                    MDF, pine, flex ply and filler.     when he comes to weld the
                                                                    “Generally the best colour to       individual chassis rails together.
                                                                    show imperfections in a buck        If you don’t get it right, you’ll
                                                                    is gloss black,” says Stuart. “If   never be able to provide a
                                                                    it looks good in black it will      consistent and accurate chassis
                                                                    look good in any shade.             to your customers.
                                                                        “In the case of the bonnet I        As a consequence of all this
                                                                    created a shape that will           work, a brand new production
                                                                    accommodate a full glass            chassis is now in stock and
                                                                    screen as well as a fly screen.”    assembly can begin on what
                                                                    You can also see that the           will become the first running
                                                                    wheelarches are also taking         prototype/demonstrator. Next
                                                                    shape, while the rear engine        month we’ll look at the final
                                                                    cover is still to be sorted.        bodywork moulds, while on
                                                                        With the major mechanical       the mechanical side it’s time to
                                                                    components attached to the          sort out the brake design.

WHICH KIT CAR? APRIL 2007                                                                                                              65
MEV’s Rocket is taking big steps towards
completion. Here’s the latest from our
behind the scenes look at its development.

LAST MONTH WE saw MEV’s new                        nose or tail high,” comments MEV’s
Rocket project take a big step                     Stuart Mills. It was then a question
forward, with the engine and                       of checking the available
gearbox dropped into place and the                 suspension travel before the
suspension design now completed.                   dampers hit the bump stops. An
But getting the car to sit correctly,              ideal set-up would see the shock
with the right ride height and                     absorber at mid travel when the
balance is obviously vital.                        vehicle is at its static ride height.
   “The first thing to note is that the            This would allow equal bump and
Rocket appeared to sit level and not               droop movement. It looked close,               Simple tunnel shape produced from folded aluminium. With no chassis rails here, this must
                                                                                              be self supporting.   Aluminium floor being cut to shape with a jigsaw.

                                                                                              which therefore suggested the
                                                                                              chosen spring rates were not a
                                                                                              million miles off target.
                                                                                                 Overall weight distribution is
                                                                                              about 40:60 front to rear, which
                                                                                              means the front springs will be
                                                                                              carrying 33% less than the rear.
                                                                                              That all bodes well for MEV’s
                                                                                              chosen spring rates with the 325lb
                                                                                              per inch of compression springs on              select harder or softer springs
                                                                                              the rear well mated to the 200s on              depending on the application.” For
                                                                                              the front.                                      an initial set-up MEV intends to set
                                                                                                 “We still have adjustments to                the damper adjustment to
                                                                                              make to get it perfect when weighed             minimum, so that if the car’s ride
                                                                                              on each corner, as the spring seat              still appears firm, then it will be easy
                                                                                              on each unit is adjustable,”                    to identify that it is the spring rates
                                                                                              continues Stuart. “Personal                     that need tweaking.
   All fibreglass body moulds have been made and production panels drawn from them for a      preference also comes in to play                     The Rocket has been designed
first fit on the chassis. Here’s the bonnet being released and the wings in place.            here, because some builders will                to use all the braking components
                                                                                                                                                         from the Ford Focus.
                                                                                                                                                         These should work fine,
                                                                                                                                                         but with the Rocket
                                                                                                                                                         weighing just 490kg and
                                                                                                                                                         the change in weight
                                                                                                                                                         distribution, there are
                                                                                                                                                         clearly potential benefits
                                                                                                                                                         from using a more
                                                                                                                                                         bespoke set-up...
                                                                                                                                                             First to go are the front
                                                                                                                                                         calipers, as these are
                                                                                                                                                         heavy single-pot cast iron
                                                                                                                                                         units. MEV has already
                                                                                                                                                         installed a pair of 4-pot
                                                                                                                                                         Wilwood units, which give
                                                                                                                                                         a total weight saving on
                                                                                                                                                         the un-sprung side of a
                                                                                                                                                         significant 8kg. They cost
                                                                                                                                                         £89 each.
                                                                                                                                                             On the rear, this
                                                                                                                                                         particular donor was fitted
                                                                                                                                                         with solid discs and a
                                                                                                                                                         combined hydro
                                                                                                                                                         mechanical handbrake
                                                                                                                                                         caliper which should
                                                                                                                                                         prove ideal.
                                                                                                                                                             Builders can also use
                                                                                                                                                         the donor’s pedal
                                                                                                                                                         assembly, but on this car

                                                                        54 COMPLETE KIT CAR   MAY 2007
                                                                                                to vented, grooved and cross-
                                                                                                drilled, while using standard spec
                                                                                                pads – early testing shows
                                                                                                excellent results whilst still
                                                                                                providing potential for further
                                                                                                improvement. The use of 17in
                                                                                                wheels means there’s plenty of
                                                                                                room for even larger diameter
                                                                                                discs if required.
                                                                                                    And on the basis that MEV has        customers driving the prototype!
                                                                                                tested the current braking set-up,            This means that kit prices have
                                                                                                those more attentive among you           also been settled on. MEV will only
                                                                                                may have correctly worked out that       offer the Rocket in a largely complete
                                                                                                the Rocket has actually been             kit form, with just about everything
                                                                                                turning its wheels in anger.             needed to get a car drivable, save for
                                                                                                    You can see from the pics that       the donor Ford Focus, seats and, if
                                                                                                items such as a polyethylene fuel        it’s being used on the road, a £465
    Fuel tank located centrally in chassis.     Original ECU and wiring loom is retained,       tank have been located and MEV has       lighting pack. The kit price is £3600,
offering a useful financial saving.   Aftermarket pedal set is optional upgrade.   Doctored     developed a bespoke wiring loom for      although there’s currently a small
picture only gives an impression of what finished car will look like.                           the Rocket which connects straight       window of opportunity for you to get
                                                                                                into the engine loom retained from       a kit for just £2995 if you order
                                                                                                the donor. This is important, because    before the Stoneleigh kit car show (all
                                                                                                keeping the Focus engine loom            prices include VAT).
                                                                                                means MEV can also make use of                Following these initial driving
                                                                                                the standard ECU, which helps to         tests, the Rocket has now been
                                                                                                reduce costs dramatically (perhaps       stripped again and the chassis
                                                                                                by as much as £1000) while having        sent away for powder coating. Next
                                                                                                the added advantage of keeping           month, we’ll follow the final re-
                                                                                                features such as a passive anti-theft    assembly of a complete car and,
                                                                                                system. Neat.                            the following month, we’ll be
                                                                                                    With all these parts of the puzzle   getting our own driving
                                                                                                in place, Stuart has now managed         impressions. We can’t wait.
                                                                                                to give the Rocket some initial trials
                                                                                                and he’s very pleased with the           CONTACT
                                                                                                results. Indeed, he’s not the only
                                                                                                                                         MEV, Ratcher Hill Quarry, Southwell Road,
                                                                                                one, since he already taken seven
                                                                                                                                         Mansfield NG18 4GT. T: 01623 655522.
                                                                                                deposits (two from Stateside
                                                                                                customers) for the car, two of which     W:
                                                                                                came as a result of potential

MEV has dumped the donor unit
with its servo in favour of an
aluminium race pedal set with twin
master cylinders and a balance bar
for front to rear bias adjustment.
Because of the Rocket’s light
weight, a servo really shouldn’t be
necessary, and MEV has instead
opted for a mechanical gain by
specifying a pedal leverage ratio of
6.25 to 1.
    Using a separate master
cylinder for the front and rear
systems provides considerable
flexibility, as it is now possible to
select alternative size units to suit
the different fluid movement
requirements of the calipers. The
larger combined surface area of the
pistons in the new replacement
front 4-pot calipers will require a
higher volume of fluid to move
when applying the brakes than
compared with the donor unit. The
selected master cylinder size is
therefore proportionally larger than
the donor’s.
    For front discs, MEV has uprated

                                                                                     MAY 2007   COMPLETE KIT CAR 55