We look BACK AT GROUP B'S ultimate NA SCREAMER
The Metro 6R4 was never able to topple the likes of the Peugeot 205T16, the Lancia Delta S4 or the Audi S1 E2 Quattro, but none of this really matters, certainly not nowadays. No, what matters is that Britain’s entry into the world of Group B rallying was one of the most bonkers looking, menacing-sounding machines to ever hit the stage, hence why we’re going to take a look back at its story in greater depth.
Most of you will already be more than aware of BMC/BL/Austin Rover’s long standing association with rallying, the firm having campaigned the Mini throughout the 1960s, a period which brought it great success and a corresponding upswing in car sales. Come the early 1980s though, and the firm was in trouble. A decade of industrial strife, economic instability and a run of duff models (take a bow Princess, Maxi and Allegro) had left Austin Rover in dire need of a boost, and the competition department eventually managed to persuade the powers that be to green light a Group B rally programme based around the then new Metro. Harold Musgrove and John Davenport were the driving forces behind the project, the men that convinced a financially precarious, naturally cautious car maker like Austin Rover to commit to such a high profile endeavor. The project was eventually signed off in 1981.
The prototype 6R4 looked far less extreme, its signature wings and splitters came later
As was the case with many of the Group B projects, timing really was everything. Had Austin Rover been able to get the 6R4 onto the stages and running well by 1983, then it might well have been a winner. As it was, development was protracted and at times tortuous, and certainly not helped by the various industrial strike issues dogging the company at the time. The decision to build the car in conjunction with Williams Grand Prix Engineering was a sound one though, and Patrick Head and his crew of F1 engineering wizards took charge of transforming the hum-drum Metro into a stage smasher.
The decision was made early on to eschew the forced induction setups found on the likes of the Quattro and soon to be launched T16, in favour of a more traditional, larger capacity, naturally aspirated arrangement. This eventually culminated in the mid-mounted 2991cc V6 that became the 6R4’s signature component. Austin Rover’s decision to go down this route was motivated by a number of reasons, the most obvious being reliability and turbo lag. Big power forced induction setups were known to provide correspondingly daunting reliability challenges, and lag times which could be measured in eons, so the idea of a smooth, unbroken power band was certainly appealing.
The Group B regulations also imposed rigid rules governing engine capacity, all designed to promote parity and foster close competition between different manufactures. These same rules severely restricted Austin Rover’s room for maneuver, mainly as, with the forced induction multiplier applied, the Metro would have been placed within a category with a minimum weight of just 960kg. This figure was simply impossible to meet at the time, not with the added weight of the four-wheel drive system factored in, and meant that the naturally aspirated, large capacity route became all the more appealing.
The sheer size of the 3.0 V6 meant that packaging the Metro 6R4 was always going to be challenge, but the combined might of Austin Rover and Williams GP Engineering rose to the occasion
The thinking that led Austin Rover and Williams to plump for an NA setup was sound but by the time the works cars made their debut at the end of 1985, the likes of Peugeot, Audi and Lancia had moved the game on: special, high octane fuel enabled stratospheric power figures, while the likes of anti-lag and supercharging went some way toward solving the gap in power caused by turbo lag.
Not only was the Metro’s V6 down on power (390bhp was the claimed figure), it wasn’t able to provide the smooth power delivery everyone at Austin Rover had been banking on. The cause of a marked drop in power between 4000 and 5000RPM was only finally identified when the team trialled a new dyno late in 1986. A redesigned exhaust manifold largely cured the problem, but it was too late to save the 6R4’s factory career. It was forever destined to lack the outright grunt enjoyed by its rivals, certainly until the rallycross boys got hold of it some years later.
Other areas of the project were more successful, its chassis and suspension being good examples. Damping was entrusted to Bilstein, the firm’s engineering nous proving invaluable in the fight to make the mid-engined Metro handle in a predictable, controllable fashion. Custom damper units were designed for the 6R4 project, with distinct hardware designed to account for both sealed and loose surface events, plus a staggering selection of custom poundage springs.
The addition of wings and other aero parts helped turn the Metro 6R4 into a fine handling car, though it was always a somewhat twitchy beast when pushed to the ragged edge
The Metro 6R4 was one of the first Group B machines to make full use of aerodynamics. Granted, Audi had dabbled with the concept with the Sport Quattro, but the Metro was one of the first to have a dedicated aero package of fully optimised parts. The only downside was that Austin Rover was forced to develop the 6R4 in the public eye, meaning that by the time it made its competition debut on the 1985 RAC rally, the cat was well and truly out of the bag! Audi’s S1 E2, Peugeot’s 205T16 E2 and the Delta S4 all sprouted wings and splitters, and the battle was well and truly on. None of this should take away from the fact that the Metro 6R4 boasted a very sophisticated and well realised aero package, with Tony Pond being particularly impressed by the difference it made to car’s ability to corner:
“I tested a car with and without wings at Gaydon. Driving it in wingless form through a section we called the ‘bomb hole’, I had to brake and drop to fourth gear. Then I did the same with the wings bolted to the car – and stormed through in fifth without lifting. The speed difference must have been 120mph against 105mph – spectacular.”
Homologation was finally granted midway on 1st of November 1985 (the majority of the 200 cars required were built on an unassuming looking assembly line in Longbridge) and the Metro 6R4 made its competition debut mere days later on the RAC rally, the final event of the season. Lancia also chose this event to take the wraps of its 037 replacement, the mighty Delta S4. Turbocharged and supercharged, the S4 showed that there was another way to build a Group B rally car, and, with the benefit of hindsight, it’s clear to see that they made the correct call.
The Metro 6R4 made its World Rally Championship debut on the 1985 RAC rally, an event characterised by mud, rain and snow
Tony Pond and Malcolm Wilson were signed up to drive the new Metro and both were on the pace from the beginning, though the latter’s rally came to a premature end thanks to transmission troubles and, in an ominous sign for the coming months, a snapped cam belt. Pond had a far more fruitful event though, taking to the car swiftly and using his exemplary local knowledge to take the fight to the dominant Lancias. His eventual 3rd place overall was a tremendous result for all associated with the project, though it would turn out be the 6R4’s best ever finish.
1986 was a mixed bag. The 6R4s were quick when they functioned correctly, but also found themselves severely outgunned by their turbocharged rivals. The drop in mid-range power was also a continual thorn in Austin Rover’s side and the issue robbed the Metro of one of its major strong points. It also had a nasty habit of eating cam belts!
It’s hard to avoid drawing the conclusion that the Metro 6R4 was ultimately a fairly unsuccessful car, certainly in terms of outright wins and championships. It was simply too underpowered, too conservative in its design, and too late to the party to make a real impact. There’s an interesting postscript to this tale though, and that’s that the Metro 6R4 enjoyed the longest career of all the Group B cars. The very traits that hampered its ability to win on the world stage meant that it was a far simpler proposition for privateers to keep running, and 6R4s could be found blatting their way through the British forests into the ‘90s and beyond. It’s doubtful whether the top brass at Austin Rover would agree, but you could make a strong case for the Metro 6R4 being one of the most important Group B cars of all, it’s just a shame that it only found its true place in the rallying world after the factory had thrown in the towel.