This entailed a complete strip down of both the donor XJR and also the 420G. The wiring loom was meticulously labelled and removed from the XJR as were all components for the aircon system, dash board gages, clocks and controls. The interior items such as the centre console were also utilised, along with the cruise control system and switches. The wheel base of both cars was almost identical and the rear suspension from the XJR was fitted including the rear floor pan so that all suspension locating points and cradle were exactly as they were in the XJR but now fitted in the 420G, including the fuel tank. The XJR front suspension cradle was also fitted in its entirety, although this required substantial remodelling of the 420G original chassis rails and inner wheel arches to fit the complete front from the XJR. The fabrication involved not only remodelling of the inner wheel arches but the mounting points for the ABS system, the original heater system was utilised but modified to take the XJR aircon system, the radiator and cooler mounts were completely rebuilt as well as the mountings for the huge 420G bonnet. This allowed us to keep a fairly original look to the 420G front end whilst seamlessly fitting the necessary components from the XJR.
Once all fabrication work was completed and any old rotten panels were replaced or repaired, we moved on to blast the complete bare shell, seam seal all panels and etch prime ready for paint. We took the decision to first fit everything back into the car after the initial fabrication work and virtually build the whole car to a point where it was a running vehicle, before we stripped it ready for paint and final fit everything. This enabled us to work through the difficulties of blending the old electrics and loom to the donor one, only utilising what was required from each. A lot of time was taken on this part of the build and left us scratching heads on many occasions. Martin Rickman an old school auto electrician saved the day and was able to get what looked like a ‘rats nest’ of wires into a new wiring loom with all components functioning as they should. The only failure was having the ECU security bypassed for the immobiliser as this was preventing a live to the starter motor, but once sorted the car started without hesitation. The other inevitable gremlins were worked through until we were able to have a fully functioning driving car with the dash lights all working and no warning lights. The dash board had to house some of the additional control modules from the XJR and the four dash gages were replaced with two ‘tweeters’ for the stereo, an oil temperature gage and an supercharge boost gage. The original 420G speed and rev counter clocks were replaced with the XJR clocks that were grafted into the original dash and whilst the wood is a slightly different colour it seems to work well, however, we wanted to retain the old steering column and indicator stalk which proved a challenge to integrate. All the other components for the ECU and ABS control module found homes under the drivers seat which was a neat solution and kept the wiring in a configuration that mirrored the XJR set up.
The central locking was installed with double actuators due to the ‘jail like’ door locks of the 420G, but worked well in the end with a new set of key fobs. The electric windows were retained from the 420G, although a little noisy added a little nostalgia to the car as we were able to graft the original switch pack in the centre console into the ‘hybrid’ version of the XJR incorporating the gear shift. We were also able to fit into the console a retro style digital radio/Cd player with USB/ipod connection and Bluetooth phone compatibility, also connected to new speaker system and tweeters. New seat belt tensioners were fitted and also built into the rear seats so inertia reel belts all round. In the rear seat we built in a little cocktail cabinet to hold four crystal glasses and a small bottle, to enable passengers to enjoy a drink when being transported and utilise the rear picnic tables as a ‘nod’ to bygone times of Jaguar luxury travel.
All the interior trim, seats , wood, carpets and headlining were completely replaced, whilst the bright work was also sent away for re-chroming. Whilst all the trim and bright work was being sorted the car was despatched to JP exhausts for the final exhaust system to be fabricated in stainless steel along with a new 6 branch manifold. The electrics were final wrapped, fixing points finalised, the wiper motors positioned and all the pipework fitted for the aircon and heater system. The car was then completely stripped after it came back from JP exhausts and prepared for final paint. The engine and gearbox were also completely refurbished with new seals, hoses, bearings and the cylinder head completely rebuilt and flow ported to maximise the boost potential from the supercharger.
The floor was first to be treated to a universal rubberised sealer over which the body colour sprayed, along with the inside of the car, the boot, engine bay and wheel arches. The body was then prepped and painted, with the roof a contrasting light metallic silver blue as the car was to be a two tone colour with the boot and bonnet displaying the same light colour and darker Jaguar blue to the sides and wing areas. Next the dashboard was refitted and then the front and rear windows, followed by the doors and the headlining. Now with a ‘west of England’ cloth to keep the period feel. Focus was then back to fitting all the new components for the braided fuel lines, brake pipes, remodelled hand brake, all new rubber mountings, having already refurbished both the front and rear sub frame assemblies, including new shock absorbers, bushes, discs, callipers and bearings. The engine bay was refitted with the various parts including the aircon heater system, the brake booster, abs system, fuse box, header tank and other components prior to fitting the engine and gearbox. The radiator, cooler and aircon rad were also fitted with new mounts and additional ‘scoop’ just below the bumper level to accommodate the additional size required for the radiator. The doors were fitted with the refurbished frames and newly tinted windows to give a slightly more subtle look that enhances the colour scheme of the car and accentuated the chrome trim. The door furniture was refitted and all electrics, central locking tested prior to the final trim being refitted, by our long suffering trimmer Phil Edge, who made a beautiful job of the seats and remanufactured door cards, as well masterminding the cocktail cabinet and centre console modifications.
Having completed all the major works, only the final items such as fuel tank fit up with now only one filler required, door frame fitting and all chrome work, we were able to fit the all the new lights and newly refurbished five spoke wheels and tyres with special XJR centre badges.
The car then underwent an MOT and vehicle inspection, we retained the historical free tax and were ready for the final testing. We spent around 3 weeks ‘shaking down the car’, with adjustments being made to the door frames, ‘squeaky’ dashboard, steering column and gear selector, to name a few issues. However, we are continuing to address any other minor points but have not had any issues over the last 3-400 miles and feel confident that the car performs as well at least as the XJR donor, if not a little louder on acceleration and suffering a little more wind noise due to the old 420G styling. One quirky item worth mentioning that we kept, is the vacuum operated air intake flap in front of the windscreen. We are nor sure how these were supposed to work when in the original guise, but due to the increased vacuum from the new retro-system the flap shuts when accelerating hard and opens again when you let your foot off the ‘gogo’ pedal. We thought it was a nice feature so have left it, as it is like the car shutting its eyes during a much improved acceleration and opening them again once settled!!!