We take a look at the how Gobstopper II was created and share a collection of never before seen images!
Gobstopper II began its journey back in 2010 with the delivery of a brand new body shell direct from Prodrive.
The body shell was the last one remaining from the World Rally Programme after Subaru decided to pull out of the WRC championship. It was an oppertunity not to be missed if Matt was going to try and recreate the same success we had experienced with Gobstopper I. The deal was done and creating Gobstopper II was now the companys next target in helping to push both RCM and the Subaru brand forward.
Having already planned in advance the necessary requirements and modifications needed Matt delivered the shell to Custom Fabrications where the extensive and skillful task of integrating a roll cage and fabricating areas to house specific components would take place:
One particularly notable feature on Gobstopper II is the complexity of the integral roll cage. The following images show just a glimpse of the time, effort and skill required to create such an asset and ensure driver safety:
Each careful addition and alteration found on the body shell is done so with the most amazing attention to detail. Every metal section is Tig Welded into place offering a neat, uniformed, and exceptionally strong join. For those of us not familiar with welding types and processes, Tig welding requires far more skill, time, patience and experience when compared to Mig welding and is truly an art form in it's self!
Further modifications carried out by Custom Fabrication included the addition of;
- "Wheel Tubs" to offer greater flexibility in ride height and wheel diameter.
- Custom top mounts to maximize geometry adjustment and add greater strength.
- Air Jack mounting tubes. Rear subframe mounts (which are attached to sections of the roll cage).
- A complete new centre tunnel to house the exhaust system above the floor.
- Compartments where the rear seats would usually be intended to fit to house electrics, and the fuel cell.
- A new tunnel in the bulkhead to allow the exhaust downpipe to exit on the opposite side of where originally intended (so balancing weight against the driver)
- Holes in the chassis legs to allow easy spark plug removal from the engine.
Other alterations included removal of excess material to aid weight saving and swaged holes to improve rigidity and strength.
With Fabrication on the shell complete next stop for GSII was with our friends at KS Composites to begin composite work on the body panels.
Weight reduction was an important factor for Matt, not only because the body shell was heavier than its predecessor Gobstopper I but more importantly the more Kilo's he could shave off the faster the car would go.
As with the shell modifications Matt had already planned the necessary requirements by identifying areas that could offer significant weight saving gains. It was a case of duplicating and creating panels manufactured from a lighter material whilst having to envisage key features that would be required later in the build process, easier said than done when there is no instruction book to follow!
Original body panels were initially fitted to provide a starting point from which KS could then modify to suit, eventually being used as the templates for new moulds.
From the moulds finished panels could then be manufactured requiring minimum alterations to help form the finished car you see today.
With the composite work complete the next stage in the process was to dummy build GSII. Before this could take place a layer of protective primer would need to be applied to the bare metal shell, safeguarding it from the elements and any potential corrosion. The key to a perfect finish relies very much on the chemistry that goes into the preparation, which is why the Body shell was taken to SGM Race Paint in Banbury who would ensure the perfect finish for Gobstopper II.
Once Matt was entirely happy with the dummy build, confident that all necessary modifications were complete a final visit was made where Gobstopper II would receive its finished war paint!
With the arrival of GSII's empty carcass back at RCM HQ the real excitement could begin as we watched Matt work his magic and the car take form:
Fuel and brake lines are installed:
Family friend Tony constructs a custom wiring harness for GSII:
Wiring, Steering components and air jack lines are installed:
Battery and safety equipment go in:
Body panels are trial fitted with hinges and latch positioning confirmed:
Carbon roof is secured:
Exhaust and matching carbon cover really look the part!
Dashboard, instrumentation, seats, harnesses and steering components all come together to form the finished interior:
Nitrous Oxide bottles find a home underneath the rear floor:
Chassis, brakes and suspension components are assembled:
Installation of the engine came next:
Exterior body panels such as bumpers, doors, rear spoiler and tailgate were all fitted. For the first time in two years we saw a true glimpse of our racing future:
Pro Forged Billet Wheels were especially made for GSII by our good friends at Team Dynamics Racing:
Aero quickly became the next priority on Matt's hit list, the more down force the better the grip, the better the grip the more stable the car will become, ultimately improving lap times.
So how do you know what aero to fit and where?
Much like you see in F1 we first needed to obtain a 3d scan of the car which we could then place in a CFD program. The results would indicate the appropriate modifications needed to obtain maximum aerodynamic efficiency whilst improving down force:
After trials with various designs a compromise was found between maximum aerodynamic efficiency and down force:
With the new additions in place it was time to visit MIRA's (Motor Industry Research Association) wind tunnel facility and observe the air flow:
Wth Gobstopper II now complete all that remained was to test the car and see if all the hard work had produced the ultimate Impreza as Matt had hoped:
Olly prepares to push the limits of GSII:
Meanwhile Matt anxiously waits for feedback:
After the first few laps out it's clear that the initial run has been a complete success. Olly comments to Matt just how impressive the handling is and the vast difference from Gobstopper I and with no mechanical gremlins the RCM team couldn't have hoped for a better result!