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The initial packaging study was done using PVC tubing, a basic wooden seat
and the TL1000r motor.
The desire was to use a Yamaha R1 engine because of its low end torque
however from the first moment it was apparent that the vehicle would
either be very asymmetrical or that the engine would protrude from the
bodywork in order to make it work. The other problem was that it
wasn't possible to sit the engine next to the occupant, the farthest
forward it would go was so that the clutch cover was tucked as close
to the driver’s hips as was possible - effectively putting the widest
two points of both elements next to each other. This also meant that
the wheelbase of the vehicle was not shortened sufficiently to
overcome the problems found in the original 1up study.
The V twin however allowed the engine to be situated much further
forward in the car. Its narrowness allowed the car to be almost
symmetrical in plan balancing the weight of the engine with the driver
and still offered the low end torque that we were after. Our only
worry was the length of chain that would be required. |
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After some initial discussions on how the bodywork would be split to
keep it as simple as possible and having agreed on a system for the
drive line it was possible to layout a simple tubular chassis that was
modular in construction and would hit the points required. We then
built the suspension geometry in wire frame to ensure that the inboard
mounting points would meet the chassis in the required places and work
as we intended. From there with the basic principals of the car agreed
upon and the major components such as the fuel tank, radiator and
engine situated we built the chassis up in the computer adding roll
hoop and triangulating where necessary.
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From here it was possible to split the work between the design team so
that different aspects could be tackled at the same time.
Because of the required geometry and our desire to use motorcycle
tyres it would not be possible to use an off the shelf wheel as the
offset would not be correct and the bike tyre needs a different
rim section to a car tyre. In addition the desire to use a common
wheel face, to reduce the cost meant we had to find a way of
manufacturing the wheel at as low a cost as possible. Initial research
into spinning a wheel face was not successful and turned out to be
more expensive than machining wheels. In the end we opted for forged
wheel face welded into a rolled wheel band. This meant we could use
the identical wheel face on all corners of the car and reduce
machining costs. With the feasibility of the wheels established we set
about designing the uprights. Again as machining is a major cost the
idea was to design something that was symmetrical across the front and
kept cost to a minimum while obtaining a look that was consistent with
the theme of the car.
After many iterations the final design consisted of a three piece
assembly that used stock material sizes at reduced dimension and
therefore cost, that required machining from only one side with a
single bit size and pressed and located over itself. The design
eliminated the need for any welding, again reducing assembly costs and
was held together by four bolts.
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The same principal was applied to the rear upright although the deeper
wheel and necessity to mount the drive sprocket meant that the rear
uprights were more complicated to machine. In addition a custom cush
drive was made based on the same idea that Ducati's use.
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The problem of a very long chain was eliminated by the inclusion of a
transfer shaft that sat on a common face with all of the rear suspension
mounts. The half shaft has several advantages the first being that in
having two chains we can completely eliminate chain snatch by having
the half shaft center exactly on the instantaneous center of the
suspensions motion. The second being that we can now change the
gearing of the vehicle very easily without having to buy large
sprockets for the rear and finally hat there is now an ideal location
for an additional inboard parking brake and - if required a reverse
mechanism.
All of the rear end is mounted onto a single face. This was decided
upon as it meant that we could use common pillow blocks to hold the
wishbones and half shaft. It also meant that chain adjustment could be
done very simply by loosening the pillow blocks and shimming them out
as necessary.
The rear plate was CNC machined to ensure absolute accuracy and then
once jigged it was welded onto the chassis.
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Front wishbones were jigged and fabricated from aero tubing while the
rear wishbones were a combination of machinings and mandrel bent
tubing.
As the projected weight of the vehicle is very small great importance
was put on reducing stiction in the suspension. Rose joint were used
throughout and rockers were mounted on needle bearings front and back.
The rockers themselves were deigned and machined with the same feel as
the uprights. While we used Penske shocks throughout.
The seat and fuel tank are the major components of the interior. The
fuel tank is a custom made epoxy cell that utilized all of the
Suzuki's fuel pump componentry to ensure that everything works
including the fuel level meter. The importance was put on maximizing
the capacity of the tank so that it would not be necessary to refuel
as often as is required on a bike. The seat and tank are designed to
fit together and form a single surface that flows from the shoulders
down to the feet. It also acts as the firewall separating the driver
from the engine which sits just an inch from the right elbow. It was
decided early on that the seat would be built to accommodate the
largest client - at 205cm tall - and that the pedal box would be
individually positioned for each client. In addition the shorter
clients would be bolstered in the seats using either a formula type
seat form or a custom made bolster.
The seat is a large open form that sits on the chassis rails. This
allows us to build padding in between it and the body panels that
overlap as the edges of the seat will be used as hand holds whilst
getting in and out of the vehicle and therefore need to be very solid.
The gear shift mounted on to the firewall between the driver and
engine and is a direct link to the existing TLR gearbox.
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With the engine installed we designed the exhaust headers to use
existing off the shelf bends and fabricated them from stainless tubing
donated to us from Yoshimura. The muffler was sourced from a local
manufacturer in CA
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At his point we also needed an accurate volume for the airbox as the
stock airbox sits over the engine overlapping it on both sides. We
also wanted to maximize the use of the area in front of the engine for
additional volume in the airbox. To do this we digitized the stock
airbox base and, because digital data was not available for the
engine, took a digital snapshot of the engine, as it sits in the chassis.
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This allowed us to build very accurately into the space between the
radiator, reserve bottle and piping maximizing the use of the
available space. All of the parts of the airbox were then CNC machined
from foam and female mould taken off them. The body panels were also
being developed in conjunction with these parts to ensure accuracy
between components.
Finally the wiring loom was modeled in to ensure that there were no
interference issues between the plugs and ECM as they sat very close
to the fuel filler neck that was situated only by the filler cap on
the exterior bodywork.
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Once complete the two major body panels were CNC cut as male masters
from clay over bead foam. We then created female epoxy moulds from
them so that multiples could be pulled without destroying the tools.
We had initially intended to cut plaster tools however with time
running we couldn't wait for the facilities to become available to us.
However smaller parts such as the rocker panels and roll hoop were
machined, in negative, from various materials like foam and, in the
case of the rocker panel, bead foam with a skin of gel coat. Giving a
very cheep tool that would not degrade with multiple pulls.
Fiber glass bulkheads were machined and inserted into the nose cone,
rocker panel and the two main body parts to ensure that when the
parts came together they fit exactly and would simply pin together.
This process of manufacture meant that we could lay up very accurate
thickness of glass by hand and not need to do any body filling once
the cured parts were pulled from the tools. In addition it meant we
could keep the weight of the panels to a minimum.
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With the chassis finished and the first test runs under our belt the
chassis were sent out to be sand blasted before being painted. The
uprights rockers and all other aluminium was sent out to be anodised
and the wheels to be powder coated. Bolts for the uprights were
Dacromet coated to isolate them from the aluminium, wishbones painted
and exhaust wrapped ready for assembly. The loom was wrapped and he
military style bayonet fittings added. When the wheels returned they
were then taken to have the tyres (donated by Avon) fitted, and the
final assembly began.
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The three cars were completed with wheel arches and lights all
together in March of 2005 just one week ahead of the first press
article was to be written by the Robb Report (See Press page) one week
later.
The first weekend after the completion the cars were taken out into
the Santa Monica mountains above LA and 300 miles put on them by the
clients. The cars were in need of some minor suspension tuning and
gearing alterations but they drove well and more than met the
expectations of their new owners.
A month later two cars reside in the US and one in the UK.
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The three SUB’s were completed, with all of the finishing touches, in
March of 2005, one week before the Robb Report (link to article) was
to write the first press article. The SUB’s digital data was 100%
complete, as they were built, months before the three were completed
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