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THE BUILD

Day 1 - 5

As expected the build starts with the bare chassis. ‘Phase 1’ as we called it was an order comprising of the bare chassis, the alloy panelling and the pedals, hoses and master cylinder etc. The trestles were also bought and delivered at this stage. The chassis its self came in the back of the truck, which was man handled into the MacG Racing workshop, and the remainder of the parts came wrapped up or in boxes, shown.

After resting the chassis on the trestles, the first and probably most laborious task of the first stages of the build is to fit the alloy panelling to the chassis. This has the function of adding stiffness to the chassis frame, whilst also giving the obvious benefits of adding protection and shielding from wind and water etc! The panels come cut basically to shape, however a large amount of smoothing edges was required, as was shaping the corners and other bits of the panelling so that it would neatly and easily fit round chassis tubes and welds etc. As with all the tasks regarding the panelling, it is important to do these jobs neatly since any mistakes will be very obvious to the eye once the build is complete, since the majority of the panelling will be in full view when sat in the car.

The first panel to go in was the rear bulkhead. It is advised before you put the panels anywhere near the car that you protect the chassis tubes that are vulnerable to scratching with masking tape, as the edges of the alloy panels so a great job of removing the powder coating from your fresh chassis! Once unwrapped, (the protective film was left on both sides until fitting) the panel was offered up to the chassis members that it was going to be fitted to  get an idea of how much material needed to be removed for it to fit neatly between the upper and lower longitudinal chassis rails. Any material removed was carefully marked out using a fine marker on the film on the panel, and either cut with a hacksaw or coping saw (if the parts were large) or removed gentle with a semicircular file. This takes a lot of patience to get right but in hindsight it is fair to say that the results are well worth it. Once the panel neatly fitted between the chassis longitudinals, it then required drilling so it could be riveted to the chassis.

We went with the factory recommendation of a rivet every 25mm. The rivets will be positioned in the centre of each chassis rail, meaning that they are 15mm from the top and bottom edges of the alloy panel. Masking tape was roughly placed along where the lines or rivets will go to make marking out and punching a mark easier. We measured and marked out a centreline vertically down the panel, and marked a hole position where this intersected the line 15mm from the top. We then worked outwards marking out the hole positions both sides from the centreline, in order to keep symmetry. The holes were marked out using a 1m precision rule so that the lines remained straight and true. Once all the holes were marked, carefully centre punch each position where the holes are to be drilled. It is imperative that the centre punch marks are in the right place; if a rivet is out of line it is VERY obvious when looking at the car!

Once all the holes have been carefully marked out and centre punched, and the panel has been offered back up to the chassis to double check hole positions etc, the next stage is to drill the panel. For the size of rivets used to attach the alloy to the chassis, a 3.3mm drill bit is required. It is probably worth buying these in bulk, minimum of 20, since when it comes to drilling the steel chassis tubes these get blunt (and snap!) very easily. Carefully drill each hole position, remembering to let the speed of the drill do the work. We used a air drill held by hand, and laid the panel onto a sheet of MDF so protect the drill bit when it comes through the panel. After each hole has been drilled, remove any swarf and rough edges from the drilled holes by hand using a 5mm drill bit. This is important to help the rivets sit neatly on the surface of the panel.

When all the drilling has been done, we offered the panel up to the chassis rails. The next stage is easier with the help of an assistant. Using a soft faced quick release clamp (a G-clamp can be used instead but makes things slightly slower) clamp the alloy sheet into the correct position against the chassis rails. Do this in at least 4 places for security. Tighten up the clamps and if necessary adjust the position by gently tamping the alloy by hand or with a soft faced hammer. When it is in the correct position, using the holes on the alloy as you guide, drill the chassis rails. We found this took a while, however it was necessary to do it carefully as the drill bits break easily, and it is easy to scratch the panel with the drill when this happens! Check every so often that the alloy has not moved and is still clamped in place correctly.

Once the holes have been drilled in the chassis, as recommended by the factory in the build manual we sprayed waxoil into the chassis tubes to help prevent rust forming. After this, we wiped the surface of the chassis to remove any excess, and cleaned the chassis rails thoroughly with metholated spirit to remove any waxoil that would prevent the sealant from adhering. Using the black sealant supplied, we applied a thin (2-3mm) bead along the line of holes in the chassis to adhere the alloy to the chassis. This sealant gets everywhere and sticks to anything (especially clothes and skin!) so be careful when using it. Having taken off the protective film from both sides, we carefully offered up the alloy panel to the chassis, and clipped it in place using the panel clips supplied in the kit.

Due to the huge number of rivets used during the build, we opted to buy an air powered rivet gun to do the riveting with. This turned out to be a godsend, as riveting by hand took roughly 5 times as long, and was not as neat. We riveted the panel on from the central rivet outwards, which we felt would give the neatest results. We wiped up any excess sealant the squeezed out the sides using an old cloth with some metholated spirit on it. Now sit back and admire before moving onto the next one!

We actually shaped all the panels for the cockpit (excluding floortray) and made sure they fitted and clipped then in place with the panel clips before riveting any of them in place, as can be seen in the pictures.

The order in which we fitted the panels is as follows:

Rear bulkhead
Side panels
Front bulkhead (requires extra trimming for pedal holes and fixing bolts)

Floortray
Steering rack tray
Radiator tray

Radiator double skin

Once the panels round the cockpit were fitted and fully riveted in place, we used a piece of hardwood to curve the alloy panel round the chassis tube where it overhung at the top. Place the hardwood block at one end of the alloy panel and hit it gently with a hammer to press the alloy round the tube. Working along the panel inch by inch found to give good results. Using a fine file we smoothed off any sharp edges that were found.

The floortray onwards was done after turning the chassis upside down on the trestles, and turning the chassis back the right way round to do the radiator double skin. There was not much cutting/trimming to be done here apart from the radiator double skin, however hindsight showed that drilling some 12mm holes with a drill into the radiator panels to allow fitment of the radiator later would have been a very good idea!!

Trimming the panel for the front bulkhead is tricky, but by carefully offering up the panel to the pedal holes and marking onto the plastic film, then drilling small pilot holes to make sure the measurements are correct was found to be the best way of achieving the necessary cuts in the bulkhead. Any voids at this stage were filled with the sealant to avoid water ingress at a later date.

Once completed, the alloy panelling marks the end of phase 1 of the build, and now the more exciting components can be attached to the chassis so it can look more like a car!

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Just Doors UK sponsoring MacG Racing
PTR Exhausts
Braid Wheels
AWS Racewear sponsoring MacG Racing
Quantum Racing Suspension sponsors MacG Racing
Albins Performance Transmissions sponsors MacG Racing
Rotary Revs Logo

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