6R4 Build Story
A remarkable combination of the latest technologies - including the use of lasers - and traditional craftsmanship were used by a 100 man strong team to build the exciting MG Metro 6R4 rally car at Austin Rover's Longbridge plant.
The 347 unique panels, designed and manufactured at AR plants, were transported to Longbridge where they joined the 16 standard metro panels to be made into the 6R4. Three jigs held the chassis, while the body sides were sub-assembled and the roll cage side hoop is welded into the 'A' post.All the major sub-assemblies are then brought into the framing station with the complete chassis. In the butterfly jig the body sides are locked together and body shell is set by the clamps and assemblies welded together. As an indication of the strength of the 6R4. the car has 137 feet of welding compared to only four feet on the standard metro - amd the 6R4 consists of 3,680 spot welds composed to 2,987 on the standard metro.
Finished weld parts are then carried to those areas that are not accessible at the framing station. Here, for example the back of the tank is added and finished.
A two-part epoxy adhesive is used to bond the aluminium roof on to the body. The roof is 'tacked' to the drip rail - by using the latest technology - self piercing rivetting. Small rivets are dispersed by air into a rivetting gun and fired through the drip rail which gets rid of the need to drill holes and fit rivets.
Fenders and doors are then bolted on. and a total of 302 holes of 16 different sizes are drilled into the chassis for bolting on the plastics, wiring looms, partitions and other items.
The car then goes through the full paint process before the ermin white vehicles are taken to the trim and final assembly building where the power train, including the engine, is stored.
In the trim and final assembly process the first step is to insert the cable ties and clips and to trim the doors. The suspension wishbones are added, followed by the foam-filled bag fuel tank. Wiring looms and electronic engine management processer.
The fascia, with unique instrumentation, Including an electronic speedometer and a unique rev counter, is then added. Next the air cleaner, handbrake, heater blower, front suspensions and front differential is added, followed by oil hoses, oil filter, the gear linkage, steering rack and front anti-roll bar.
After the rear inner wheel arch liners have been added, the power train is fitted in from the rear of the vehicle. This comprises engine, gearbox, step off, and rear differential. Wheels, rear suspension and rear anti-roll bars are added to make the car mechanically complete so that it is ready to be filled with oil, water and petrol. Brakes and clutch are then bled. The car is started and taken to a four-post lift for wheel alignment.
Seats, rear quarterlights amd the bulkhead are now added amd at this point the final 23 plastics fittings are put on, including fenders, sill, door duct, bonnet, front spoiler, wing supports and tail door. The hand build is totally different from the metro - even the windscreen washers are unique, in that the water jet comes from the wiper blade.
On power train the vehicle is also unique. The only carry-over part from the standard metro production is the gear change knob and even that has different graphics because it is a five-speed box.
The engine is tested for two hours on the Radford dynamometer and a power curve is produced for each engine before it is mated to its transmission prior to shipment to Longbridge.
The end result is an off-the-shelf rally car ready for any body with around £35,000 (although Austin Rover's Motorsport division who handled the sales said the price was negotiable) to spend. Theoretically they say you just get in, turn the key and go off on your own 'Winning Streak'.